* General Considerations
* Engine
* Transmission

Submit corrections and additions to this information to The Olds FAQ Compiler.

General Considerations

Speed is a question of money . . . how fast do you want to spend it? A couple of things to consider:

  1. Will the car see street/everyday use?
  2. Longevity or ultra high output?
  3. Drivability? (closely related to #1)
  4. Stock look or pro-street?

First, the factory parts make a good foundation for your engine, so you don't have to get too exotic.

Second, you have to plan the whole package, so you need a camshaft that will match the gears and the converter needed to get your car moving.

Street vs Race

The problem with any race engine vs a street engine is flexibility. The engine in a street car must operate over the entire power range from idle to 5000 or 6000 rpm. Virtually all race engines are optimized to provide max power within a narrow operating band, followed by ensuring (through gearing) that the engine remains in that operating band for as long as possible. The result is that in both stock cars and drag cars, you'll see carb, port, and valve sizes designed to maximize HP at a very specific (and usually high) rpm. The tradeoff is that HP, and more importantly, torque, is down dramatically at lower rpms.

The classic example of this is the Ford 351 Cleveland motor: the heads used on the 4bbl cars have ports which designed to optimize high rpm flow and power, with the result that the 2bbl heads, with their smaller ports, are a much preferred choice on the street. Ultimately, the best street motor, IMHO, is the one with a torque curve that's as high and as flat as possible from 1500 to 5000 rpm. Torque rules on the street, and the 455 Olds is one of the best torque motors around.

If the car is going to be driven everyday it will need to be able to ingest pump gas with little ajustment. (timing, octane boost etc.). NHRA Stock and Super Stocks run the ragged edge of disaster, and are definitely not streetable.

Build the engine to run with whatever gears you have, it can be done. There's no absolute need for 3.90 gears out back! If you know what you are building for, select the components that make the combination work. Low lift flow. Build for torque! You have 455 CID to deal with! The biggest problem I see with Olds and Pontiacs, is people expect slow block tech to work on them. It doesn't. The slow block needs to rev to make power, the Rocket motors don't and neither do the Indian motors. You can have a faster car with a 3.08 gear than most any slow block with 4.11.

A radical cam will make the car hate traffic. If you have a hi-po carb it will tend to run rich and load-up. Choosing the right cam is an important step to total performance. Too much cam and you have a dog, to little and it's a wimp. Vacuum is also a concern if you have power brakes. Auto transmissions will need a higher stall converter which will cause overheating in traffic.


Let's first, if we may, talk about the cost of the motor to run in the 12's without blowings kablooey.
Stock Rebuild = $1500 = 15.0s (Maybe)
Perf. Rebuild = $6500 = 12.0s (Maybe)

[ Notice: ]Please refer to the Rebuilding section as well!
[ Notice: ]Please refer to the Best Big Block section as well!
[ Notice: ]Please refer to the Best Small Block section as well!

[ Thanks to Danny, Bob Barry, Gary Rubrich, Thomas Martin, Gerald Hughes, Joe Padavano for this information ]


303, 324, 371, 394 (1949 - 1964 Rocket)

1954 and 1955 324s' have smaller intake ports and valves than the 1956 engines. 1955 and earlier four barrel intake manifolds won't fit a 1956 engine unless you put a dent in the lifter valley cover. 1957 and later cylinder heads will physically bolt on to 1949 to 1956 engines, but the port matchup on intake maniflolds will be off because different cylinder deck heights are used. 1957 and later cylinder heads have larger coumbustion chambers and valves.

Offenhauser still offers an 8x2 bbl intake manifold that uses Stromberg carbureters, and will fit all 1949 to 1964 Olds engines, by varying the length of a pair of tubes that connect the two halves of the intake manifold together. Offenhouser still makes dual four barrel and three two barrel intakes for the early Olds engines, but those manifolds are specific to the engines they are made for (one doesn't fit all). Offenhauser made a number of intake manifolds for the early Olds engine. And they continue to do so.

[ Thanks to for this information. ]

[ Notice: ]Please refer to the 303 CID Engine detail section as well!
[ Notice: ]Please refer to the 324 CID Engine detail section as well!
[ Notice: ]Please refer to the 371 CID Engine detail section as well!
[ Notice: ]Please refer to the 394 CID Engine detail section as well!

260, 307, 330, 350, 403 (1964 - 1990 Small Block Rocket)

[ Notice: ]Please refer to the 260 CID Engine detail section as well!
[ Notice: ]Please refer to the 307 CID Engine detail section as well!
[ Notice: ]Please refer to the 330 CID Engine detail section as well!
[ Notice: ]Please refer to the 350 CID Engine detail section as well!
[ Notice: ]Please refer to the 403 CID Engine detail section as well!
[ Notice: ]Please refer to the Diesel Engine detail section as well!

400, 425, 455 (1965 - 1976 Big Block Rocket)

[ Notice: ]Please refer to the 400 CID Engine detail section as well!
[ Notice: ]Please refer to the 425 CID Engine detail section as well!
[ Notice: ]Please refer to the 455 CID Engine detail section as well!

Big inch Small Blocks

The big-block main bearing size is one reason the diesel blocks are able to be used with a big-block 425's crank to get a 440ci+ small block Olds. Mondello has a complete kit to turn a diesel block into a big CID small block. It is a blockless engine kit, uses Buick rods, custom pistons.

I'd like to go the other way, and cut down a 425's crank to fit in my 403's block (the way the Ch*vy guys cut down the mains on their 400's crank to drop in a 350 for 383ci, just a bit more radical). As far as I know, that's never been done, though if it were done, you could have a _500_ cubic inch small-block Olds, given the 403's huge bore size. I've got a spare 403 block just waiting; now all I need is a trashed 425 crank and lots of cubic $$$!

[ Thanks to Bob Barry for this information ]


Boring the engine will increase cubic inches, I've had great success at .060" over. Going with a gear drive timing setup will assure dead-on timing although it does whine a bit. High-volume oil pumps only if you use oil restricters and have loose crank tolerances. The most important thing you can do for any 455 is to balance it. This will not only make it last longer but free-up HP. Yes, we've all built motors without balancing, but you'll be a lot happier if you do.

10.5:1 forged pistons (it will actually be lower, but this is the nominal compression you should be shooting for)

Block Curing
Remove the main bearing caps, clean all joining faces, reassemble and torque to specifications. The block should then be heated (with the caps mounted) to 1050F and held at this temperature for two hours. It should then be furnace cooled to 500F at a cooling rate not to exceed 200 degrees per hour. The block can then be allowed to air cool until normal temerature is achieved.

After stress relieving, new cam bearings and core plugs should be installed and the old main bearing cap bolts should be replaced. The piston bores can then be honed and the decks machine cut to insure that they are flat and parallel to the crank centerline. The main bearing bores will also have to be checked and bored or honed if out of alignment.

Cam Technology

Dump the W-30 cam. It was hot in 1970, but it is not 1970 anymore. Try a JM 20-22 cam (or the next one up). Makes power everywhere, up to 5500 or so.

[ Thanks to Scott Mullen for this information ]

Computer Control

Since the computer only controls the primary side of the electronic carb, as well as the ignition advance, there's no reason to discard it.

The stock computer should work (even with the stock chip) if you swap a 350 in place of the stock engine. The only difference it would make to the computer is in the carburator calibration (more air=more fuel), and from what I've read, the stock computers are able to make this compensation without any problem.

As for a modified 350, that might be another story. If you keep it mild, the stock chip could still probably compensate for it, but if you go too wild with your cam, the funky vacuum signal could create some problems. A cam only a couple steps hotter would probibly be ok.

I would probibly go with a performance chip anyway if the budget allowed, since it would allow the car to take full advantage of the bigger motor (better advance curve, etc.) You might check with Hypertech and Jet and see what they recomend. But, there really shouldn't be any reason that such a swap wouldn't work just fine.

[ Thanks to for this information. ]


Add an additional tranny cooler, recore your radiator or get a new one, make sure you get sufficient airflow past it and through the engine.

That fact that the engine overheats in traffic, but not on the highway, indicates that your radiator is sufficient in size, but that your airflow at idle/low-speeds is insufficient. You need more fan, plain and simple.

A shroud will be a necessary part of your solution. Are you running the stock fan, with a thermostatic clutch? Generally, that's the most efficient fan setup; use electric fans as supplements to a thermostatic, shrouded clutch-fan. Until you get to the baseline established by the Olds engineers for the efficiency of airflow, you'll be guessing as to what will cool down your motor sufficiently.

Of course, the problem could also be insufficient water flow; is your water pump in good condition? Is the belt tight? Was the impeller firmly attached to the shaft? In one notorious case, the overheating at low-speeds was caused by the impeller freewheeling on the pump shaft!

A high stall torque convertor is not helping matters any. With a high stall convertor and a rebuilt 403 with a 3-row radiator), the car was running hot (205°-210°) in traffic, and it stayed at 180° on the highway, not matter what the outside temperature. Changed to a thermostatic clutch on the fan, and now, on hot days sitting in traffic, the temp might rise to 190°, but usually stays in the 180°-185° range.

Seriously, you need more airflow past the radiator; the electric fans are not enough. A clutch fan with a shroud, especially when combined with the electrics, would not cost more hp, and should pull more than enough air. Also, a 7-blade Toro fan is preferrable to a stock 4-blade fan, though any 5 or 6-blade fan would also work better (common on many later air-conditioned Olds).

Have you checked to see that the fans are running when the engine starts overheating? The thermostat that switches on the fans might be bad or maybe you have a loose connection going to them. If the fans aren't working then the car would overheat in traffic but stay cool on the highway. One of the fans themselves could be bad. They can spin and look like they're working fine, but they might not actually be pushing enough air to cool anything. Make sure you can feel a good breeze coming from the back of the radiator. If not, then one of the fans might be loafing. It's possible even for new fans to be defective.

Did you buy "pusher" or "puller" fans. They are different. I would opt for one pusher and one puller (on the appropriate sides of the radiator). Also, you should wire a manual override to turn the fans on when you sit in traffic.

Trans fluid should stay below 250 if possible. Anything more and you risk cooking seals, depending on how long the trans has to put up with the extra heat.

[ Thanks to Bob Barry, Greg Pruett, Dan Lacey for this information ]


Scrapers, Windage Trays
FWIW I have been told by some "powertrain" engineers at Oldsmobile that scraping the oil from the crank reduces reciprocating mass and can add up to 15 H.P.

When you change your oil, and inadvertantly drop the plug into the drain pan. When you get it out it's (of course) completely covered in oil, right? A gooey runny mess, right? Think about how much you hate getting that crap on your hands, when it slowly oozes down to your elbow as you're trying to wipe it off. Another example, for those who've built engines. Remember dipping the piston assemblies in a coffee can filled with oil before installation? When you pulled it out, there was some amazing amount of oil stuck there (and a lot less in the can)? More of that "adhesion" property coming through here.

OK, now remember that. It's a given that the crankshaft is coverred in oil constantly. Oil seeps out of the bearings, and through the splash holes, etc. It gets flung around the crankcase, and, if the block is painted, quickly tries to run back down. Whoa, wait, there's another obstacle, a crankshaft. Suddenly it's a ping-pong game. Some actually makes it past, but a lot of the oil just bounces around. The crank-scrapers and windage trays pull the oil off of the crankshaft before it has a chance to get flung upwards. That about covers the Oldsmobile-famous problem of sucking the crankcase dry.

Next aspect. Reciprocating mass. Remember that drain plug? And how it weighed like eight pounds when you got it out of drain pan? Now think about the engine building process, ever had one balanced? Remember what it involved, and ~why~ it was done? To keep the reciprocating assembly running perfectly smooth. You know how much of a difference one ounce will make on a tire, same goes on an engine. You get that thing perfectly balanced, and it just sings.

So lets put it all together here. We have a perfectly balanced 350 (assume). We can even paint the inside of the block. We get 'er up around 5 grand, with 45 psi oil pressure. It's cranking out great, spurting and splashing everywhere. It's draining back as fast as it flies up. It's splashing as it flies back into the oil pan off of the crank. It's dripping right back onto the crank and rods. It should be pretty easy to see the crank fairly coverred with oil, right? Where should it go? If it stays on the crank, it'll gather on the throws and weigh it down. All that balancing work, just to lose it from the oil? It doesn't take much.

Granted, this is all theoretical. Different grades of oil will yield much different results, etc. However, from a theoretical point of view, doesn't it make perfect sense to use a crank scraper and/or windage try? It's often said that balancing, intakes, exhaust mods, etc. are for racing only. Nonsense, that's just the application that requires it. Normal driving applications will benefit in drivability, smoothness, overall performance, economy, and emissions, in some instances.

[ Thanks to Charley Buehner for this information. ]

Main Bearing Cap Straps
Milling the main bearing caps .500" is only necessary if you are installing a full length oil tray also. Otherwise the stud/strap kit will fit fine on stock caps with no additional machine work needed.

[ Thanks to Bob Handren for this information. ]


Unless your stock exhaust system was posing a restriction on airflow, moving to headers would not improve performance significantly. Increase noise, yes, but a louder car is not necessarily a faster car (though it may feel so). If you went to headers, you'd also have to change the transmission crossmember, and add an exhaust system on the other side of the car. Probably about $600 by the time you're done. Dual-exhaust manifolds.

[ Thanks to for this information. ]

Gears, Torque Convertor

You need to know what gears you have in there, and what stall converter you're going to be running, in order to realize the benefits of a high-hp motor. All of the above mods are designed to move more air through your engine, but you have to allow your engine to be moving at a higher rpm. If not, your car will be dog around town, but really start flying at 80mph! (ask me how I know this)

What you need are 3.23, 3.42 or 3.73 rear gears (heck, go with 4.11's if it's a weekend-only machine that will never see extended highway driving), and a 2400-2800 rpm stall converter. Then, you can use a cam like Mondello's JM 18-20 or JM 20-22 to get decent torque down low (which you'll need, even with the gears), but some real pull through the gears.

If you don't mind a choppy idle and neck-snapping engagement, I suggest you go with a peformance canmshaft and torque converter. A performance cam will open and close the valves much quicker, and hold them open a little longer, which lets the combustion chambers breathe better. But if you install a cam that is far above the factory one, you'll need a torque converter with a higher stall RPM. There are two reasons for this; one, it won't engage until the engine has started the powerband, giving you quicker accelleration. Two, a wicked cam has to idle higher than a factory one, otherwise the engine will bog off the line, or cough out.

[ Thanks to for this information. ]


Any of the following heads, in order of preference: F, D, K, C, Ga, G, E, B, J, preferrably with the A.I.R. bumps in the exhaust ports ground off (you can also port-match the intake and exhaust manifolds if you have lots of free time). If you've already got the 1970 "E" heads, stick with them; they won't be slowing you down.

Porting and polishing the heads will help the breathing. Also, what heads you use will determine how expensive the work will be. Look for 2.072 intake valves. Heads C, D, E and F are good because of the chambers and availibilty of the large valves (some Cs and Es have smaller valves)

Any head from the #5's to the #7a's (basically, from 1969-1972) will have the smaller combustion chambers, and will give you decent compression, and flow well too. The 7a heads from the 1972 350's have the advantage of factory hardened exhaust seats, if that is a concern to you.

Blocking Crossover Passage
I've wondered why anyone uses the "Mondello" alloy for filling the heat riser. I melt old cast pistons in a flea market cast iron skillet. I lay the head intake side down on a steel plate, and preheat the head to 150°F. I pour the molten aluminum into a little fixture [trough] made from 1X1 angle iron that i stick into one of the bowls. I pour it in until it runs out both bowls. I've done several sets of heads, and the cast aluminum has held up well, even on daily drivers.

I believe that the idea of using the cast iron skillet is that the skillet will hold the heat and even it out. Once you heat the skillet past the melting point of the pistons it will hold the heat and keep the aluminum liquid long enough for you to pour it. Basically the higher you heat the skillet the longer you will have to pour the aluminum because it will take longer for the iron to dissapate the extra heat.

As far as doing it with a propane torch the key thing is using the "rosebud" tip which is fairly large and has a large flame so your able to heat a larger area. If your propane torch has a small flame tip then your only going to be able to heat a small area at a time which, if your trying to heat something as large as a skillet, will allow the rest of the surface area to dissapate the heat.

Break pison apart with large hammer, get a cutting torch. Heat the thing up. It'll melt. Took under 5 minutes to melt a 425 slug. A skillit might not be the ideal container to melt in. Need to use something that will keep the melted aluminum in a small area so you can keep the heat on it. I used the iron cap from a big oxy. tank. Skim all the crap off the top, pour into exhaust ports (dont stop in mid pour) till it runs out valve seats, grind excess till smooth being careful not to touch the actual seat. This is a really simple operation.. takes maybe an evening max. I find it hard to believe there have been so many posts on this..

I use a std oxy-acetylene torch with a "rosebud" tip (large heating tip). I place two old greasy, dirty cast pistons in the cast iron skillet and apply the heat directly to the pistons. They melt right down, and all the impurities float to the top. I scoop the junk off the top and pour. It's really not a big deal. Please be careful if you do it though. That molten aluminum is dangerous.

On a former daily driver [79 toro w/77 403] i wanted a little heat for the carb, so i inserted a piece of 1/2" e.m.t.[conduit] into one of the bowls on one head. I stuck the conduit down through one bowl, and let it stick up out of the bowl, while i poured through the other bowl. Once i poured, i was able to grind down through the alum on the intake side, and find the end of the conduit. A bit of grinding was needed to cut of the section sticking into the bowl. This way i had a little heat from one exhaust port going to the carb area.

On my 64 Cutlass [461"] I cut my exhaust side back .175". This was enough to create a gasket area apx .125" wide between the center ports.

Optional -You can also grind the roof higher until you have only about .1875" from the top of the port to the top [outside] surface of the head. This makes it harder to match the header, but it will help flow, as it takes some of the downhill slope out of the roof. You can slot the bolt holes on the header with a die grinder, or weld them shut/redrill to raise the header up to help the port match the header.

Dave Smith once told me that pouring the heat risers and cutting the exhaust side back/raising the roof is worth 40 hp on a 455. The best part is it gets rid of the "bub, bub, bub" exhaust sound.

[ Thanks to Dave Brode, Mike Bloomer, Ken Rotten for this information. ]


I'm not a big fan of single plane intake manifolds on the street, preferring the dual plane setup I'd recommend the Edelbrock Performer. As for your manifold with the angled carb flange, that's intended to keep the carb level under hard acceleration when the nose of the car comes up.

Oldsmobile big blocks ARE torque monsters, but in the lower RPM ranges (generally). At a given point torque begins to drop off as horsepower increases. The Torker manifold is, in my opinion, misnamed. Since it is very inefficient until you get to the 2500 RPM range, and peak torque has (often) already been reached and surpassed, it is really a better manifold for horsepower than torque. Unless you are building an engine that horsepower band is from 4000 to 6500, stay with the Performer. Its made for torque at low end with good midrange. Olds engines are usually lower RPM motors (<5500 RPMS).

A good dual plane manifold has been PROVEN to make better power (read torque) in the lower RPM range. If a car is built to operate in that range and the manifold is designed for a higher RPM range, performance WILL be hurt. If the tranny is shifted before it reached an effective range for the manifold, it will translate into higher ET's. If you are looking for more top end, add a 1 inch carb spacer plate.

Factory cast iron 4-bbl intake (1964 to 1972 except 1969 (to avoid the choke-well and EGR features), or the Edelbrock Performer to save weight (not much improvement in the way of HP, though)

[ Thanks to Ed Binnix, Mark Prince for this information. ]

Big Valves, Small Valves
Small ports/valves and intake/exhaust runners keep the velocity of the incoming intake charge or exiting exhaust charge higher relative to larger ports and larger valves. The larger the ports and such, the faster you have to spin the motor to get sufficient velocities to get a good fuel mix and combustion and fill the combustion chamber.

[ Thanks to Jim Hurd for this information. ]

Air Cleaners
With an open element cleaner, you may experience some part-throttle stumble from the carb leaning out due to more airflow. You can rejet to compensate for this, though an electronic carb might compensate automatically on the primary side. The secondary side isn't computer-contrlled, though, so you might need to change the rods there.

It will definitely be louder, and sound faster. You'll be drawing in hot underhood air, rather than cooler air ducted from in front of the radiator support. You'll also have to plug the vacuum lines that connect to the aircleaner. It may help make the car feel peppier, or it may make it sound peppier, or it might hurt driveability some at part throttle but improve it at wide-open throttle. One quick way to test this out before you buy anything is to flip the aircleaner lid (you might need a longer air-cleaner stud to get this to work) and see how the engine responds. If you have some stumbling at part-throttle with the lid flipped, you'll have more stumble with the new air cleaner.

The trick setup, of course, would be a dual-snorkel air cleaner from the H/O/442, ducted to cool outside air. I'm still looking for this setup to use on my 409, which needs the extra air, but which I want to have impeccable part-throttle driveability characteristics (it stumbles a bit there with an open-element air cleaner).

[ Thanks to Bob Barry for this information. ]


HEI distributor (from any '75-'79 Olds small-block) is pretty good stock, and hard to beat after being properly setup for the application (recurved ignition advance).

If you want to recurve the distributor, but the recurve kit that comes with 3 types of springs and 1 set of weights. Dwell requirements are the same for all the Olds Point distributors.

A HEI housing is larger than the points dist housing so the guts are not interchangeable. What makes them interchangeable is the length of the distributor shaft (housing to distributor gear) is the same. The distributor gear is the same for points and HEI.

The vacuum advance modules are identical from 1974 and up for the HEI distributor off 350, 403, 455, 260 engines. The 307 is computer controlled. As for points, the 330, 400, 455 up til 73.

Among points distributors, the weights are all basically the same. The same applies to HEI distributors. However, point distributor weights are different than HEI in design and are not interchangeable. The cam gear of all the distributors are the same. The springs are pretty much the same for both distributors.

[ Thanks to Mark Prince for this information. ]


DO NOT USE lifters from companies that list the same for Olds as they do Pontiac. There are differences. Oiling holes are one. For good stock type lifters look to PAW for them. They are around $39.00. Lifters for 66-67 Big Blocks 400 and Toro 425s are $65.00.

Same goes with Pontiac. Do not use lifters that are listed for Chevy and Pontiac, the grove for oiling is different. It is higher on the Chevy. With a Pontiac and a high lift cam you will lose your oil pressure. I have seen the same lifters for Buick as well, but I don't trust any unless they all have a different part number.

[ Thanks to Jim Chermack, Thomas Martin for this information. ]


Olds oiling systems aren't as bad as most would think. My race engine builder Danny Lattimore, (who is the one that has a 10 sec Olds in D/Stock class, 70 SX with a 455 in it), has been building these things as long as Joe Mondello has. He has never found half of what Joe says to be true. If you want to listen to all Joe has to say you'd buy all His parts and have $5000-$10000 in an engine.

It's true all the neat things make an engine sligthly more efficient but you can have yourself a great street engine for under $3000.00. One that will go a very long time. If you put oil restricters in the block at the bearings your not really accomplishing what you want. I would go with rotating the cam bearings slightly where it feeds oil to the lifter galleys and put a stock regular oil pump in the engine with a 4 quart pan.

Make sure to run near the max limits on all your bearing clearances. We run .0031-.0033 on the mains and .0025-.0027 on the rods. NEVER had a problem. Studs are not required for the bottom end either. Good bolts work just as well. On an engine rebuild the best money spent is in the cylinder heads and the cam with impeccable assembly practices and you'll have one heck of an engine.

In the oiling picture, you can see that the oil comes from the oil filter back into the engine where it goes up one side of the lifter gallery to the front of the block, intersects with the timing chain oiling feeds, main oiling feeds, and the lifter gallery on the opposite side. The mains get fed from front to rear on an Olds engine, and the rods in turn. Every time we've had oiling trouble or even questions about the system (before I got smart and had Dave Smith build us a quality oil pan and system), I would check out the #7 & #8 rods and the next to the last main bearing since they're the last to get oil pressure and the first to lose it. This is also a good way to judge the condition of an engine you're buying, I wouldn't buy a used engine to drop in and run without looking at the bottom end. If they don't want to let me look at this, the price drops down to what I'd pay for a rebuildable core.

[ Thanks to Ken Snyder, Jim Chermack for this information. ]

Oil Pumps
If you keep the rev's below 5 grand your stock system will be fine. People are being misled here. Olds' have an oil volume problem, not pressure. These are two different animals that often get confused. High pressure does nobody any good if there is not any oil to pump. In an Olds motor the oil must be returned to the pan as quickly as possible or the pan may be sucked dry. 40 psi pressure warm is more than enough. Too much pressure, say over 80 psi is hard on an engine too.

In my 85 Cutlass Salon I run a Toro 5 quart pan with a Diesel oil cooler filter adapter and a diesel radiator with a Fram 1 quart filter PH 11. I have a total of 8 quarts with this lo buck stock system. I run a Melling HV pump that runs around 60 psi. This car runs 12.80s all day at the track with no oiling problems. With short bursts to 5800 RPM the 8 quart system works great.

I did port the rear main oil flow passage off of the pump mount for better initial flow. I think this is very important. I also polished the return valleys under the heads to the lifter area for faster oil return to the pan.

My 455 in my boat is subject to long bouts at 5500-5700 rpm. A 5 minute cruise at this RPM is not uncommon. I use a Dooley Enterprises 14 quart pan on that motor. I also have a dual remote filter set up. It takes FOREVER to change the oil in that baby! The pump is a high volume with a special pick up for the big pan. The rear main has been ported too. The engine internals on my boat are the same as my '85 Salon.

The way to improve your pressure on the Melling, or any oil pump, is to assure that the gear to cover clearances are correct. Take your oil pump to your machinist and have them check that the gears are the same length and that you have minimum clearance to the cover. A gasket might not be needed.

A Fram HP25 will also give you more pressure at idle than an HP2. If you are going to do all that work to replace the rear seal you might as well put on a larger capacity pan and you will not have a problem with sucking the pan dry. Use oil restricted push rods and and grind the oil return holes in the block and heads and you should have no problem. I have heard that main oil restrictors are good and bad.

[ Thanks to Tony Waldner, Al Varhus for this information. ]

High Volume Pumps
HV oil pumps do pump more per/rpm than the standard volume oil pumps. You may have been told or heard that the oil pump's pressure relief valve pops open at a set pressure, directing all the excess oil back into the oil pan before it goes up to the top of the block.

I used to think that the protrusion jutting from the oil pump spewed oil back into the pan. However, recall that inside there is a solid piston- the pressure relief piston. Oil cannot flow past it in any large volume. What happens when the pressure relief is activated is that the excess oil pops the piston open, and is directed back to the pump's *intake area.* Not back to the oil pan. Since the oil passages remain a constant diameter, you are pumping exactly the same amount of 55psi oil at 4000rpm using a HV pump as you are using a standard pump; the pressure relief valve is just allowing more of the HV's output to go allowing more oil to bypass back to the pump inlet. A subtle but important difference.

I suppose that in theory, the pressure relief might not be able to keep up with the extra output of the HV pump, but you would know this when you saw the oil pressure climbing at high revs beyond what the pressure relief valve spring is rated at (if you don't know what that is, you can figure it out once you run your engine much above idle, as a HV pump will "max out" rather quickly at a certain psi and stay there no matter how much you rev your engine- for example, my 403's HV pump hits 55psi by about 2000rpm and stays there, no matter what I rev it to). In that case, you would need some reserve oil, because the drainbacks in the heads would be the bottleneck for the extra oil going through the lifters (which are kind of "oil pumps" themselves).

As for the oil restrictors, they only restrict flow to the cam bearings (refer to a diagram of the Olds V-8 oiling system to confirm this one), not to the lifters or the pushrods or the upper end of the engine. A reversible way of achieving the same thing is to drill a smaller hole in your cam bearings, and install that hole facing the oil feed hole from the main journals. To restrict flow to the upper-end of the engine, you need restricted pushrods.

On most Olds engines, they have a tendency to over-oil the top end. If you look at the oil flow picture in the service manual, the restrictors (per Dave Smith) should be in the front center oil line and the oil lines going straight to the cam bearings on the next three back. In this position, the only thing to get less oil is the cam bearings. Now on our solid lifter cammed 350's, we also add a second restrictor to the front web, but it's on the side that does not supply the mains. These are the only lifters that get any restriction from this system, the only way you could restrict all the lifters/pushrods would be to drill and tap each lifter oil hole and install a restrictor in each one.

I'd forget the oil restrictors. I've heard of too many people having this kind of problem. Remember, Olds didn't put them in the original W-31.

[ Thanks to Ken Snyder, Mick Gillespie for this information. ]

Extra Capacity Pan
Consider this: you can have a high-capacity oil pan in a couple days via mail-order for about $200, including the extended pickup. How much have you already sunk into the motor? Is it worth the extra peace of mind to have a couple extra quarts of oil on hand to feed your engine? Then again, unless you start running this engine at a constant 4000rpm, you really won't encounter this problem. This is your call.

Diesel Oil Cooler
The diesel Olds V-8's have an extra quart of oil capacity because of the oil cooler they are equipped with. Not from an extra-deep pan, as in the Toronado oiling system. The oil pan is the same, though the gasket is more sturdy.

The trick setup, using factory parts, would be the Toronado oil pan (along with the sturdier gasket) and the diesel oil filter mount with the cooler adapter lines, for a total of a 7-quart capacity using factory parts.

Oil Return from Heads
The oil goes up top. Here is how to get it back down to the pan faster. Complaining about leaking valve covers? This modification solves that, and more importantly, helps oil return to the oil pump. Here goes:

I did this project when I had my mill (just torn down and still dirty) on the stand, so that is the only way I'm going to recommend doing it. Full credit for the idea of an external oil return system goes to Joe Mondello, who told me he does this to race and marine (i.e. heavily flogged) engines. By the way, the purpose of this whole thing is better oil return. The leak free valve covers are a nice bonus.

First thing to do is get your die grinder out and enlarge the oil return hole (downward) that is located at the front of the lifter valley. Blend the lower side of the hole downward so that any oil coming down from the front oil return holes does not pool in the valley, but instead will drain immediately down through that round hole.

Next, use your die grinder to smooth out the entrance to the oil return holes located at either end of the cylinder heads. This is especially important for the rear (towards the firewall) holes, since the natural tilt of the installed engine pools the oil to the back of the head. Typically, these holes were simply drilled into the head perpendicular the head surface, so there is alot of improvement that can be made to the entrance of the hole. The end result should look like a funnel. BE VERY CAREFUL ABOUT GRINDING TOO MUCH!!! You want to make a funnel, not a canyon. Just use a fairly fine burr in your grinder so that a nice satin finish results.

Closely examine your oil return holes and you'll see that the large gallery drilled in from the valve spring area is intersected by a small gallery that actually returns the oil to the valley. For the motor head with a good collection of burrs, a long shaft burr with a small (¼") head can be used to do some limited smoothing out of the intersection of the galleries. By looking down the large gallery, you can see that the oil must climb uphill to reach the entrance to the small gallery. Since oil can't climb, it pools in the valve spring area until it reaches a high enough level to spill down the small gallery. With my engine on the stand and the valve covers/intake manifold off, I poured oil over the valve springs to simulate the oil return process in a running engine. I had oil all over the floor and none coming out the return hole into the valley. That explains why my valve covers would frequently leak. They were literally holding about 3 ounces of oil each due to the poor oil return design of the Olds cylinder head. Six ounces doesn't sound like much, but I want every ounce in the oil pan, not in the valve cover area.

Make sure you have each head on the correct side of the engine (I think they're interchangeable too, but I've always kept them on the same sides; don't ask me why...) You will be installing 90 degree elbows on the back of each head. I did this four years ago, and as I recall, I used ¼ NPT fittings. Once you read this, you can decide on the size of the plumbing for yourself. I drilled a hole into the back of the cylinder head to intersect the large gallery that comes down from the valve spring area. Use a depth gauge or similar tool to determine the correct spot to drill. There is a bulge in the casting that corresponds to the gallery, so this is pretty easy to do. Ideally, the bottom portion your drilled hole will intersect the large gallery at its bottom. In this way, you will get maximum drainage without drilling into unknown territory. Tap the hole for the appropriate thread size. Repeat this operation on the other head.

Next, you'll have to decide where to drill the back of the block to install a tee fitting. Joe Mondello recommended using the machined portion on the vertical part of the block(right below the area where the rear intake mani seal would go) near the distributor hole. The important thing here is to place the hole lower than the holes you drilled in the heads, so that gravity can do its thing. You won't have a whole lot of difference in height between the block holes and the head holes, since the block hole will have to be drilled high enough to allow you to screw in the tee fitting (that's an important thing to check BEFORE you drill!!!). As I recall, my block hole is about ¾" lower than the head holes. Before you drill, make sure the distributor clearance is accounted for.

Now, you simply connect the heads and the block using your choice of braided steel line or fuel line. Joe uses braided aircraft hose. I used metal fuel line because I had just spent most of my available pennies on a RAM clutch and pressure plate. I should not have used metal line because 1) the bending and precise lengths required really taxed my patience and 2) when I was smugly enjoying the rather nice finished result, it dawned on me that I could no longer remove my distributor! Once the engine is reinstalled, space is very tight, and there is no way you're going to get in there and disconnect metal lines. I could rotate the distributor for timing changes, but removal was not possible. Off came the metal pipe and on went ½" heater hose with double clamps. Make sure you keep the set up flowing downhill from heads to block, but tight enough to allow easy engine installation. Since the oil return is not under pressure, braided line is total overkill. But guess what I'll be switching to next time the motor is out for PM? Yep, Mr. Mondello's advice to me has never been wrong. I'll be installing braided line.

This has been a long posting, but it's worth it. Once you have the engine on the stand, this will be much easier to conceptualize. When I repeated my oil pouring experiment, no oil went through the stock rear return holes in the head. Every bit went through my newly installed return system. Complimented by some contouring with the die grinder to the rear of the valley beneath my newly drilled hole, the oil now returns down the back of the valley, directly above the sump. The important thing about this project is to carefully visualize and do lots of "mock-ups" before you drill anything. Also, clean everything thoroughly when you are done (meaning garden hose clean). Now my valve covers never leak, so I've been able to switch to the extra-thick Mr. Gasket cork gaskets, which gives me clearance for Mondello's SAR-455 adjustable roller tip rockers under stock valve covers. One more thing, this set up is virtually invisible when installed, so even stock purists can take advantage of a race proven oil return system. I've had my hood opened up for some pretty sharp Olds fans, and nobody has ever spotted it. However, it is difficult to service any leaks, so do it right the first time or get your hoist ready.

Next time I have the engine out, I may reroute these lines down the side of the block and then directly into the oil pan. Should be fairly easy and more accessible in case of leaks.

[ Thanks to Scott Mullen for this information ]

Plugging Oil Bypass Valve
I would only do this if the engine is in something you take care of and change the oil regularly, since it would suck to have the oil filter plug up, causing zero oil pressure in the middle of nowhere. I had an accurate oil pressure gauge plus had the factory idiot light still working so that in the event I did loose oil pressure, it would catch my attention instantly.

It's actually quite simple. On the aluminum filter adapter that bolts to the passenger side of the motor there is an internal passage that has a spring loaded plate in it. When the filter clogs up the oil goes through this passage to maintain oil pressure. As I remember (been a couple years since I did this) all I had to do was to pry out a steel insert that held the plate in, remove the spring, then drill/tap the hole for pipe threads. Install a pipe plug and all your oil is forced to go through the filter.

[ Thanks to Mike Bloomer for this information. ]

Diesel Oil Pan
Diesels use the same pan as the gas 350. Extra oil is all in the cooler circuit. It does not drain back on shutdown.

[ Thanks to Frederick Nissen for this information. ]

Toronado Oil Pans
Although I personally do not consider the Toronado pan to be a performance part, it will give you an additional quart of oil capacity over your small block pan. Which will help keep the temperature of the oil down. This makes it a good choice for lower rpm applications such as towing, etc. However, for the most part, this additional quart of oil is kept in a second "sump" area in the front of the pan. This second sump (with no drain back provision to the oil pump pickup) is required on Toronado's for clearance of the drive axles. And this is what creates the problem with using a Toro pan in a performance application. This front sump places the crankshaft's counterweights directly in the oil.

For one, this creates windage that reduces horsepower. At high rpm, this will also throw the extra quart of oil up the right side of the block/crankcase. Although the Olds engineers did add a deflector to the side of the Toro pan to minimize this problem, the oil is not in the pickup area of the pan where it is needed the most at high rpm. In addition, because the crank is spinning in the oil sump, this will aerate the oil. Which creates a foamy and thereby poor lubricating oil condition.

The Toro pan has no rear sump baffle that was used on all other big block pans as a means of keeping the oil in the pickup area under hard deceleration/braking. Instead, the Toro pan requires the use of a short baffle (or windage tray) that attaches to the fourth main cap (and one of the oil pump bolts). By the by, this windage tray will also fit the other Olds pans and I recommend using it.

The Toro pans also have another baffle attached to the number one main cap as a means of reducing windage caused by the timing chain being in the front sump area. In my view, as a performance part, the only redeeming quality of a Toro pan is the bolt on baffles. Not the pan itself.

Toro pans are larger in both depth and fore and aft dimensions of the sump. Depends on the body and exhaust configuration of the car you are putting it in as to whether it will fit. On most it precludes a single exhaust as there is no place to put the crossover pipe. The oil pump pickup tube is longer.

As for the dipstick difference's, they are the same length with full and add in the same locations. Between the Toro and non-toro oil pans, FULL is the same distance below the pan rails. Olds motors want to run the level just under the crank weights. I investigated this extensively one time. Turns out there are a couple different standard tubes & sticks to match. All correct matches have the same level at FULL. The Toro pan, being a bit narrower, has the ADD mark about 1/8" lower than others'. I think the 307 tube has a slight bend in it, if that makes a difference.

The Toro pan has a deeper sump; it holds five quarts (plus one in the filter for six total) while all other Olds pans (big block, small block, and diesel) only hold four quarts (plus one in the filter). The Toro pan will fit an A-body chassis (can't speak to G-bodies; I assume someone like Charlie will have the info). The oil pump is the same, but the pickup tube is longer for a Toro. Toro pans will fit all 64-up (except 394, of course) Olds V8 blocks, big and small. The diesel pan is the same as all other small block and and only holds four quarts; its the additional volume in the oil cooler that gets the system up to six.

The later Toro 350 and 307 pans differ from RWD pans in appearance but not capacity. They look deeper and less wide. This is to clear the final drive unit. The 403 powered Toro's used in '77 and '78 use the same 6 quart pan as the early 425 and 455 cars, but they do not have the baffles that bolted to the main caps like the big motors did.

[ Thanks to Greg Rollin, Frederick Nissen, Joe Padavano, Tony Waldner, Bill Reilly, Chris Witt for this information. ]

Factory Oil Pans
There is a signifcant difference in big block and small block oil pans. There are 2 big blocks (Toro, and non) and the small blocks are all the same. My Olds engineering documents show three distinctive pans. PN's are 391440 (4 qts) for small block, 399270 (4 qts) for big block and 398438 (5 qts) for Toro. Pickup tubes are the same for both the 4 qt pans. The Toro has a different oil pump pickup.

The 455 pans have slight bulges just ahead of the sump to clear the rotating crank/rods. Small blocks don't need the clearance hence those pans have no reliefs. All the aftermarket pans have bulges so they fit either engine. Factory 455 pans fit small blocks but the reverse is not true.

The main difference between the 65-72 small block pans and the big block ones is the baffle used on the big block pans. This baffle is designed to keep the pump pickup submerged in oil under hard deceleration/braking. Now just why the Olds engineers felt this was not necessary on the small blocks (even the W-31's), I couldn't say.

[ Thanks to Jim Chermack, John Pajak, Greg Rollin for this information. ]


High Compression Alternative
A cheap way to build an 11-1 motor is to use TRW BB Chevy 396+.060 or 402+.030 or .060 [396s are cheaper]. Cut the dome off, and have the olds rod opened to .989. The compression hieght is a bit higher on the Chevy pistons, so need less deck cut to get "0" deck for good quench. The weight is close enough that you don't need to balance, and if you shop around for the machine work, you'll come out cheaper than using 2323s. I had it done a few years ago, and speedomotive cut the domes off for $6 each (i bought the pistons from the shop).

You gain about 12 or 13 cc this way[flat top with one uneeded valve notch]. If you have an early block you can use std bore 427 Chevy pistons [4.25" bore] and build a cheap 482" @ 11.4-1 or so w/80cc head, and a zero deck.

The 400 sb Chevy piston cannot be used in the 455 because it has the wrong compression distance, and the Chevy sb wrist pin is only .927, not .989 like the Chevy bb. There are no flattop 396/402 bb Chevy pistons available [that i know of].

The 396/402 piston [w/dome removed] in the 455 is a very simple and straightfoward piece of hottrodding. It gives you a true 10.2 - 10.3 to one engine, with no deck cut, and an 80 cc head. A so called 10.25-1 olds 2323 piston will give you around 9.2-1 with no deck cut, and an 80 cc head. This is using a 4.155" bore, and felpro head gasket.

[ Thanks to David Brode for this information. ]

Port Matching

For many years I've thought intake port matching was not worth the trouble. In fact, for some intake manifolds you can end up ruining the "aim" of the intake runner design and negatively affect cylinder fill. Some years ago I read that it was definitely not recommended to port match the Edelbrock Torker for this very reason. Looking at a Torker it is obvious that some of the runners are shaped such that a large portion of the intake port on the head is not being fed. Why would they design it that way when they can do most anything they want with a new design? To positively affect flow efficiency is my guess.

Lo and behold there is an article in this months Car Craft (see, that C*evy biased rag is good for something) where they dyno tested a big block engine before and after port matching. Bottom line - no significant difference. Something like 2 HP and a couple lbs-ft of torque. Glad I haven't wasted all that time and money over the years.

Forget about port/gasket matching your intake/heads UNLESS the intake has larger passages than the heads. Then, and only then, is it worth it to even consider this expensive (if you pay someone else) and time consuming exercise. And I don't care how careful your are, how do you know that after everything is torqued down, run and re-run a couple dozen times, that your "port match" is still perfect. You could easliy introduce edges that can mess up the flow as much as help it. Waste of time for sure on a street driven car and probably also for 99% of race engines.

[ Thanks to Bob Handren for this information. ]


A well-built, nodular iron crank, solid-main block 350 could live well to 6500 RPM, or safely see the high side of 7000 RPM with a forged crank; the camshaft that would allow you to reach those heights, however, would not be very responsive below 2000-3000 RPM, so build it for the 2000-5000 RPM range, where you'd be driving it most of the time. A diesel motor could reach the same RPMs, but would be able to survive the pressures of supercharging or nitrous as well.

Roller Lifters

Roller lifters and cams were in all 1986 and up 307's, and most 1985 307's, and diesels after 1980. An easy ID is the heads. 5A heads have no roller lifter, 7A heads have the roller lifters. These lifters are of 0.921" variety. This is the same diameter as the 39° cam bank angle cams used in 1966 to 1967 Toronado and 442 blocks. The 45° cam bank angle cams might use a slightly different lifter.

[ Thanks to Tom Lentz for this information ]

Aftermarket Roller Lifters
I'd go with the steel roller tipped badboys. The reason for this is that Aluminum Roller Rockers utilize a "needle bearing" setup at the fulcrum. Yeah this is nice for reducing friction, but after a little bit of use, the bearings begin to wallow out their seat in the aluminum! This causes the owner to have to adjust them every month or two, and most of the time unable to figure out why his dang rockers won't stay adjusted! Aluminum rockers are generally good for about 12 passes, and then their worthless (this is pretty good if you're tearing down the engine constantly for races).

The steel rockers don't have this problem. They are a little heavier, and don't have a roller-bearing fulcrum, but they do have roller tips. Mondello's set seem to be high quality and easy to deal with. So if you're dealing with a daily driver, it would probably be wise to use steel.

The Comp Cams kit included detailed instructions to make sure the lifter is at base circle on the cam. Then you tighten the nut, in Dick Miller's view, a full revolution for Olds engines. I can get the directions later at home if you need them and post. If your intake manifold is off you could just eyeball the lifter to see whether its on base circle. The key is that the lifter be at or very close to base circle. BTW, Mondello suggests tightening 1 and a half turns. Judging by the additional tension on the nut I thought that was excessive and have not had problems with tightening them just one turn. Tightening with the engine running sounds like a big mess, plus I don't think you could get an accurate starting point, which should be just as the pushrod gets some resistance to being twisted.

Another suggestion, the studs should go in at 20 lbs, not 25, per the Comp Cams helpline. He said 25 is just too much for those little guys. Lastly, take the time to make sure the pushrods are not offcenter such that they push the rocker arm sideways. The rocker arm should line up straight and even on the valve tip head. You may need to adjust the guideplates to allow the pushrod to do this.

[ Thanks to John Ramsey, Todd Morris for this information. ]

Stock Roller Lifters
These lifters roll on the cam surface, rather than slipping, so there is less or not tendency to develop a wear pattern if properly oiled. This allows or facilitates reusing these lifters. The roller lifter engines also used guide plates on their roller lifters. Mondello says that the diesel roller lifters are too heavy for performance use. I guess weight would be a valid concern.

In talking to a few cam mfrs, they all reminded me that a hyd roller lifter is nothing more than a hyd lifter w/ a wheel on the bottom. Look for no more than 6800 rpm. Weight would be a problem, but at very high revs. How about for the masses who think 5000 rpm is plenty? Remember, JM is out to SELL PARTS. Not exactly unbiased. His version, which looks virtually identical, except for a coat of paint, is around $50 a lifter.

I suppose you could use the large (.921") Diesel or late 307 lifters in a large lifter block. These lifters usually have 3/8 ball sockets, so you need to swap in 5/16" sockets or use 3/8 ball p'rods. Substitute a Smith or JM high-lift roller cam, and the power output would go up accordingly. Not cheap at $300 for the cam alone.

A recent development (for the masses anyways) for roller lifters in a performance application is a rev kit. There are basically springs which put pressure on the pushrod end of the lifter to extend the usable RPM range of the lifter (keep them from floating). Seems to me that rev springs wouldn't be too hard to find or fabricate for an Olds application.

[ Thanks to Charley Buehner, Chris Witt for this information. ]

Roller Rockers

Roller rockers use studs. The stock rocker assemblies use bolts.

You might have to change the pushrods when upgrading to roller rockers. This depends on the geometry of the rocker kit. If the rocker geometry is changed, you will need different length pushrods. Check to see if the ones recommended in the kit are a different length than the stockers you have. If the kit doesn't include/require the pushrods to be changed, it might be a good time to do it anyways. Buy a new set because the tops of the old ones could be worn out or just a ton of crud in the old oil holes in the pushrod.

You will need guide plates, and the kits furnish these. The Mondello/Harland Sharp 7200 series rockers do not use guide plates and are very easily adjustable. The function of the guide plate is to prevent the rocker from rotating around the stud and thus falling off of the valve tip. In the stock configuration, the rockers actually ride on trunnions (think of a mini rocker shaft) which are tied together by the strap or the one-piece cast rocker pivot (depending on which you have). This obviously prevents the rocker from rotating side-to-side.

Most adjustable rocker designs will allow the rocker to pivot side-to-side about the adjusting stud. While there are a number of ways to prevent this (Ford, for example, uses "rails" on either side of the end of the rocker which fit over the valve tip), the guide plates work well and are easy to install. The guide plate prevents side-to-side motion of the pushrod, which, since it fits into a cup on the rocker, also prevents the rocker from rotating side-to-side.

Screw in studs are offered that are of the 7/16" variety. While the greater strength of the 7/16" stud is desirable, stepped studs are available (5/16&qupt; on the head side and 7/16" on the rocker side) which eliminate the need to machine the head for the larger studs. They clear the stock valve covers but NOT the baffle side, so you could cut out holes for clearance in the covers. Mondello provides allen head screws to hold the rockers and fit the stock stock rocker screw holes in the head. You might try extra think rocker cover gaskets to clear the oil baffles under the covers?.

I haven't actually used the Harland-Sharp rockers, but their reputation is outstanding. The hardware is extremely well made. BTW, these are the traditional roller rockers with a small roller at the valve tip and a large barrel roller for rocker pivot.

Competition Cams also markets a "hybrid" adjustable rocker (part #1-442-16)which uses a small roller at the valve tip and a Chevy-type pivot ball for the rocker pivot. While obviously not as heavy-duty as a true roller rocker, this ball pivot design is somewhat less expensive. Keep in mind these are not full roller as the pivot point is still a ball, but the tips are roller and it provides you with the ability to adjust your valve train and eliminates the stock "bridge". Probably take an hour or two to do the install. Absolutely positively no machine required for the Magnum rocker kit. You'll still need to use the guide plates, however.

Competition Cams roller-tip rocker set for your engine. The kit includes pushrods because the stock ones will be too short after adding the rockers. And since the new rockers need guide plates (otherwise they will flop around a lot), guide plates are included. The rockers, studs, guideplates and hardware are all included in the kit. the kit for the 350 uses 3/8" studs not 7/16", and no machining is required. They are fully adjustable. Great addition for the money.

I second this. I've been running these for about a year now. No problems. Just remember to use Loctite on the studs, and I recommend a set of polylocks instead of the crimp nuts that come with the kit. I used them because the crimp nuts kept backing off my #5 cylinder. They run about $50 and are cheap insurance. At least in my mind.

If you buy polylocks, you might have to remove the baffle in the right valve cover so the polylocks would clear. You can probably get away with using a thicker (or maybe double up) the gaskets. Mine only sat maybe a 1/16" too high. You can probably reshape the baffle with BFH (or a small one too) and gain enough clearance. I haven't had any problems with goo leaking without the baffle.

Polylocks are a generic name (kinda like Kleenex). They are basically a big nut with an Allen screw in the top to positively lock the nut to the rocker stud. They are about 2" tall and since you have the Allen screw in the top, sit higher than a regular nut. You won't see the top of the stud.

You do NOT need aluminum roller rockers on the street, no matter what anybody has told you. While it's true the roller bearings reduce temperature, friction, and all that other marketing hype, you are looking for dependable and street performance. The stock ones must have worked well, that's why Olds didn't change it.

[ Thanks to Joe Padavano, Mark Prince, Mike Rothe, Randy A. Geisel for this information ]

Small Blocks General

Small blocks are a lot more cam sensitive than BB's. As a rule for a street car with a SB, don't go over .490quot; lift and 230° dururation at 0.50" lift.

Stroker Engines

Small Block
If you want to stroke a motor, start with a 350 diesel block; the main bearings are the right size for the big-block crank, and it's strong enough to contain it. Your 307's lightweight block wouldn't last. Theoretically, you could also destroke a big-block with a diesel crank. With the later 400 block, you would get a 319 CID big-block. But why bother?

Big Block
Since the offset grinding by definition requires you to reduce the diameter of the rod journals, strength is always an issue. Joe M uses Buick and BBC rods in these applications, as both use smaller journal diameters (something like 2.2" in the case of the Chevy, vs 2.5" for the normal BBO crank). Obviously you also need a shorter rod and different pistons with a relocated pin and likely skirt mods to clear the counterweights. As with any stroker motor, you need to check clearances inside the block, primarily rod-to-cam, rod-to-oil pan rail, and rod-to-bottom of the cylinder. Obviously balancing the reciprocating assembly is a challenge and may require Mallory metal (tungsten, or is that tung$ten), which has a greater density than cast iron.

493 Big Block
This is one very nasty torque monster. I had one in a 66 442 with a M-22 and 3.90 gears. It was difficult to drive due to the huge amounts of torque. It did twist the frame and tore up the cowl of the car SO bad it was removed. They also love a lot of cam and carburetion. I was running a .560 lift cam with 262 degrees duration at .050 lift and a 1050 Holley Dominator on a Port-O-Sonic intake. Engine made 511 hp and almost 600 lb ft of torque. Hoosier Quick Times were the tires of choice. They could still be overcome with the engine. Car ran the best of 11.23 @ 118 mph.

Block: 1968-1976 Olds 455 block, cleaned and Magnafluxed for cracks. Sonic check is not necessary; any 455 block will accept an .060 overbore without problems. Notch block for rod/crank clearance. Remove excessive casting flash, V-out oil return at front of block. Deck for .020 negative deck. Align hone if necessary. Use a stud and strap kit. (Must machine .500 from main caps #2, 3 and 4).

Crank: Nodular iron crank, Magnafluxed for cracks. Offset grind to 4.500 stroke, weld fillets to improve strength and to narrow rod joumals for Buick V-8 rods. Reduce counterweight diameter to clear bottom of piston. Crossdrill, chamfer, heat treat, shot-peen and micro polish.

Rods: 455 Buick forged steel rod, Magnafluxed for cracks. Polish beams, shot-peen, fit with ARP rod bolts and resize. Grind sides for clearance and add side notches (.500 wide, .010-.012 deep, both sides). Buick 455 rods are used and the block has to be clearanced..

Pistons: #2065 Speed Pro/TRW piston. This piston, unmachined, will yield 10.5:1 compression with an 81 cc head. Hone pin holes to accept one-inch Buick wrist pin.

Rings: #3070 +.065; Speed Pro plasma-moly ductile ring, file fit. .014-.016-inch top gap, .010-.012-inch second, .015-.050-inch oil ring. Piston-to-Valve: There is no need to worry about this clearance unless using a cam over 270 at .050, and over .575 lift.

Engine characteristics: Engine will have a slightly racey idle at approximately 1000 rpm. Will produce approximately 500 horsepower and 525 ft-lb of torque on readily available pump gasoline. 5500 to 6000rpm redline.

You will not inccure too much cost buiding one of these execpt for the crankshaft work required for the change in stroke. Buick 455 rods are easy to find. Make sure you put a good oiling system together for this engine, remember if you use a high volume pump to increase the oil pan size and use restrictors in the engine to keep the oil at the mains.

You should also be warned DO NOT spin this engine much over 5500 RPM. 6000 is possible but there is alot of stress being put on the bottom end. With a mild cam (ie. .560 lift, 320 duration) this thing will make almost 460 hp and about 580-600 lb ft of torque. Make sure all the body structure is in good shape and you may want to use a engine torque strap to help make the drivers side engine mount live a little longer.

Do not use any transmission other than a TH-400 behind this combo or you could really start tearing up you driveline. The cylinder heads on this combo should be pocket ported and have a good three or four angle valve job. It will help it breath better. A warmed over Q-jet or 850 Holley and a good pump works well for a fuel system. Unless you get radical with this engine there is no need to go to a Dominator carb. They do like the 1050cfm model though. Hold on to your socks when you punch the throttle though.

[ Thanks to Jim Chermack, Bob Barry, Joe Padavano, Kerry Kroger for this information ]

Food for Thought
I really enjoy figuring out stroker combos. The 2.5" journal on the big Olds crank allows for a big displacement increase through offset grinding. The Buick 455 rod[2.25" pin] can be used, although it is short. The stock bb chev rod[2.2" pin] is really to short, but affordable aftermarket versions come in 6.7" and 6.8" lengths. The mopar 440 rod[2.375" pin] can also be used, but the pin size allows less stroke increase than the others. Rods that are wider than the Olds rods would need narrowed, or the Olds crank would need to be modified for a wider journal. Counter weight to bottom of piston clearance can also be a problem with a short rod, as in the buick rod combo.

BTW the 6.7" and 6.8" bb chev rod is used in most of the popular 514" ford 460 stroker kits.

Divide the rod length by the stroke to get the rod/stroke ratio. This is what affects loads on the cylinder walls.

There are different ways to figure the required compression height with any combo, but i think the easiest way is this:

stock stroke X .5 + stock rod length + stock c.h. = a given number
new stroke X .5 + new rod length + stock c.h. = a given number

The difference in the two is the number you must subtract [or add] from the stock c.h. A stroker combo can be a bit "higher" than stock, as most Olds' have quite a bit of deck clearance. Most engine builders agree that a tight deck clearance has many benefits. Info on quench as well as the c.h. of most popular pistons can be found at

I think the bored and stroked 454" Diesel kit that Mondello sells[or did] uses an 425 crank, slightly offset ground to a 2.2" pin size/4" stroke, with a stock BB chev rod, and a special piston. This kit has the same bore/stroke as a stock 454 chev.

I've taken the diesel specs from Mondello's tech guide. I assume they are correct. Here's how i see it:

                                    stock diesel   stroker kit;
stroke                              3.385"         4"
rod length                          5.88"          6.135"[bb chev]
piston c.h.                         1.770"         1.2075"
[.5 x stroke] + rod length + c.h. = 9.3425"        9.3425"

Notes - i'm not sure what the stock deck clearance is on the diesel. This stoker crank combo requires a bunch of "heavy metal" slugs to balance it. It would be a very expensive engine. Here are some other combinations that can (I believe) be done to add inches. Some are high buck. I have figured the stroke increase on the stroker combos to be .020" less than what is theoretically possible.

473" 455 [4.21"x4.25"] +.085" overbore/455 crank/425 Olds rod/.+060 pontiac 455 piston - pontiac piston fits the olds rod. This would be a good high rpm combo, as the rod/stroke ratio is improved with the 425 rod. A KB # 222 or other pontiac piston may even have valve notches that would work?

482" 455 [4.25"x4.25"] +.125" overbore/455 crank/std bore TRW 427 BB chev piston with dome removed, and olds rod's small end opened to .989"[custom pistons would probably be lighter than trw chev pistons]. YOU MUST USE A SOLID DOME chev piston. Hollow dome pistons cannot have their dome removed.

508" 455 [4.25"x4.48"] +.125" overbore/455 crank offset ground to 4.48" [2.25" pin]. Can use buick 455 rod, but this 6.6" long rod results in a poor rod to stroke ratio. Mondello uses the buick rod in the "motorhome" stroker kits, with a smaller bore. Requires the counter weights to be ground to clear bottom of piston. One could also use a "long" aftermarket pontiac rod[2.25" pin]

514" 455 [4.25"x4.53"] + .125" overbore/455 crank offset ground to 4.53" [2.2" pin]. Must use 6.7" or 6.8" aftermarket bb chev rods [apx c.h needed would be 1.535" and 1.635"]. Note- these combo could use a KB #224 and KB #204 pistons. They are flat top bb chev pistons.

384" diesel block 350 [4.25"x3.385] +.193" overbore/ 350 gas rod/stock diesel crank. Could possibly use a std bore 454 bb chev piston, but why worry about saving a few bucks if you are building a diesel based motor?

373" gas 350 [4.185"x3.385"] +.128" overbore. Can use +.060 425 piston [same c.h. as 350gas]. Does anyone make a forged 425 piston anymore?

Note - you could use a rod with a 2" journal size, and offset grind the sb crank a bit, but the increase would be minimal.

I recently asked for input on the 425 crank in the gas sb. IF the main journals could be cut down to fit the gas block, we could theoretically build a very big small block out of a 403 block. I think it could be done, but I doubt the 403 block would take it. 4.391" [+.040"] x 3.975 [stock 425 stroke] = 482". 4.391" [+.040"] x 4" [same stroke as the Mondello kits] = 485" 4.391" [+.040"] x 4.33" [.020" less than the largest theoretically possibly increase] = 525"

[ Thanks to Dave Brode for this information. ]

Tuning and Cheap Bolt Ons

Nothing short of swapping the 307 for a 350 or 403 (either of which would fit beautifully and look absolutely stock) is going to make the car into a true road rocket, but here are a few things you might do, that are nearly free:

The problem, of course, is that improvements to your airflow (intake and exhaust) really won't help, since your 307 is probably not very restricted by the current intake or exhaust system. To move more air, you'll need to open the valves longer or higher, or spin the motor faster. That takes a bit more money.

In the long run, it might be more cost-effective to simply swap out a well-running 350; you can probably get one for about $300, rent a hoist for $40, and put all the accessories from your 307 on the 350 with about $10 of gasket sealer. Can you swing $350 and a couple weekends?

[ Thanks to Gary Rubrich, Bob Barry for this information ]

Turbo Charging

You could gain 50% in horsepower, without much penalty in fuel economy. Just be aware of the packaging problems you'd have; you'll have to work out some custom exhaust plumbing, an appropriate induction system, heat shields, and then of course the turbo(s) itself, and the associated intercooler, oil lines, etc. Figure $3000, for a basic system, unless you weld exhausts yourself. Oh, and the bottom end had *better* be built to take the boost (forged pistons, prepped rods, O-rings, etc...), which you might have been doing anyway. Figure a good $1500-$2000 for a good bottom end, parts and machining.

How long would it take, though, for you to save $5000 in gasoline? A nitrous system would be better, $$$-wise: though the basic block prep would be the same, the induction system is much simpler.

A turbo would be a poor way to add power to this engine; everything would be custom made, and it wouldn't improve your power in most driving situations, where you want low-end torque. A good camshaft properly degreed into the block, larger valves, perhaps some porting, an aluminum intake, and some true dual exhaust manifolds would give you plenty of power. Also, get at least a 2.73 rear gear (better yet, a 3.08 or 3.23 posi), if you don't have one already. The problem with a naturally-aspirated 455 won't be making power, but controlling it.

I'd hazard a guess that custom headers, to a blow-through turbo unit, etc. would run around $2000. A good cam is only $125. Your call.

Take any short stroke eng and put enough juice (turbo nos ect) and it will run, for a while. I work for a company that makes custom turbos,, and most of our customers just keep turning up the boost until something breaks. If you took a low comp. Olds motor and put a turbo system on it, it would make more power than you could put to the ground without a good four link suspension.

The trouble is the torque vs. rpm thread. Torque is measured and horsepower derived from a formula. In a contest of quickness lasting 1/4 mile, one needs the perfect balance of both. You need torque to get moving and horsepower to have a good trap speed. You can cheat either way with gears. If it was an exact science there would be only one perfect combination for each class.

[ Thanks to Larry Pegg, Bob Barry for this information. ]


[ Thanks to for this information. ]

Vacuum Alternatives

I made my own vacuum canister for my 72 H/O with a rather "lumpy" cam. I just went to the local boneyard and got a vacuum canister out of a mid 80's Lincoln Continental (looks similar to a coffee can with a bracket attached), I then drilled a hole large enough to accept a rubber grommet as used in a power booster assb. and installed a check valve from a power booster assb. on one end, and drilled another hole on the other end of the canister to accept a brass 3/8" barbed hose fitting. Mount the canister where you can, (I chose on top of inner fender so as not to be able to see it), run a 3/8" hose from original vacuum source to the check valve on the canister, then run a hose from barbed fitting on canister to check valve on power booster. Worked great for me, and cost about $10 for materials, sure beats the $40 they want for the canister alone.

One easy way to get an aux. vacuum source is the F*rd/Merc*ry method used on the Escort/Lynx/Tempo/Topaz/Ranger units with the diesel engine. It was an electric vacuum pump that switched on and off as needed. All you need to do is to tie it to a "live on ignition only" lead. Ought to be a few in yards. You could mount it anywhere under hood, and it doesn't care whether it's upright or stuffed in a fender, just one hose on the outlet. It even has a small foam filter on the intake. It's about the size of two large oj cans end to end.

Most 1985 and up FWD Cadillacs have an electric vacuum pump on the driver's side area, accessible from underneath the car, near the front bumper. These should be more plentiful than the diesel F*rds, and simpler in operation since it runs continuously with the ignition on.

If you don't want a used pump, any large RV facility should have access to electric vacuum pumps. A lot of the large diesel motorhomes still use a vacume operated heater and AC controls, therefore the need for the pump. I know the one that we currenly use is about the size of a pack of cigarettes. I am unsure if it would produce the volume needed to run power brakes and vacuum HVAC controls.

What I came up with was to find a diesel Chevy truck (any Olds powered diesel vehicle will do). For the power brakes it had a hydraulic booster, the Hydroboost system, which uses a special power steering pump to provide boost for the brakes. Put this booster in my Cutlass, ran the lines and had no problems ever again with the brakes. The engine then only had to supply vacuum for the A/C and heat. I think I got the booster and the lines from a junkyard for around $40 3 yrs ago. Good tip for all those guys who revert back to manual brakes because of radical motors on the street.

[ Thanks to Frank Boerger, Kevin Wong, Steve Bettis, John Kreitzer, Mike Bloomer for this information. ]


The most important decision, however, is your cam, which will be affected by the fact of what car it is going into.

High-lift long duration cams over .500" lift require head modification and hi-po springs. The first limit on the valve lift is when the retainer starts hitting the top of the valve guide, at about .520". Though you should have thought of this before, you can machine down the valve guide boss to increase this clearance. Mondello also sells a tool to do this, which also allows you to install positive-seal teflon valve seals. An all roller valve train is available through Mondello. This could free up as much as 30 hp.

The other thing to be concerned about is lifter preload; how much do you have? If you have too much, you can use shims; if you have too little, you can use longer pushrods combined with shims. Or, you can just spring for an adjustable valvetrain, but you'd need one of the bolt-on systems, rather than the 7/16" stud systems that require machining (unless you are ready to take the heads off again). Mondello and Dick Miller Racing are the only sources for these setups, and you're up in the $300 range with them. Also beware, Mondello's low-price stamped-rocker adjustable valvetrain is simply the stock setup with a pack of shims thrown in. Make sure you know what you are getting.

[ Thanks to for this information. ]
[ Thanks to Bob Barry, Danny, Chris Witt, Joe Padavano for this information ]


Ford transmission fluid (type F) can be used in a GM TH-350 or TH-400. Do this only after a complete rebuild. You can not mix the two. The shifts are harder, and it wears the friction plates a bit more. If you have a GM auto done correctly with a shift kit and HD parts, it will have neck snapping, tire chirping shifts even at light throttle.

[ Thanks to Jim Chermack for this information ]

Table of ContentsIndexAcknowledgements

Best BBBest SB260303307324330350371394400403425455Diesel
Rebuilding • Buildup • SwapRestoreOption CodesWheelsIgnitionComp Ratio
The W'sThe H/O'sThe 442'sToronado88 / 98 / StarfireCutlassJetfireWagons
Basic Tech How ToMiscellAll VehiclesAdditional Information

 Rocketeers have navigated these pages (since April 10, 2000).

© 1996 - 2000 by the members of the Oldsmobile Mail List Server Community. All rights reserved.

Submit corrections and additions to this information to The Olds FAQ Compiler.