Cams
Carburetors
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Cams |
Carburetors |
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The cam casting number found on the casting itself, and bears little or no relation to the grind performed on the lobes. Cam use is identified chiefly by the pattern of chamfers on the front OD, the location of the notches on the front face, and occasionally they were kind enough to actually put the last 3 digits of the cam PART # on the back of the cam.
Here's the chart produced by Karl Sarpolis that was originally printed in the Feb/1995 issue of JWO. All credit is his. Note that the part # is not the casting number.
Olds Camshaft Specifications 1964-1977 Over Duration Lift Year Part # lap Int./Exh. Int./Exh. Application 1964 387484 52 278/282 .430/.432 330 Police Pursuit 577994 36 250/264 .380/.390 330 2BC, D88 2BC 1965 387484 52 278/282 .430/.432 400, 330 4BC ST,425 ex Starfire 388992 47 278/282 .430/.432 J88 4BC, 330 4BC AT 558528 36 250/264 .387/.388 330 2BC 388828 50 286/280 .427/.461 425 Starfire 1966 588528 36 250/264 .387/.388 330 2BC 388992 47 278/282 .430/.432 330 4BC AT 387484 52 278/282 .430/.432 425 ex Starfire 388828 50 286/280 .427/.461 425 Starfire 393964 52 278/282 .430/.432 400 AT ex. OAI 393859 58 286/286 .472/.472 400 ST ex. OAI 390961 55 281/282 .472/.472 Toro 397328 82 308/308 .474/.474 400 OAI (W-30) 1967 396188 36 250/264 .387/.388 330 2BC lo-comp 396192 47 278/282 .430/.432 330 4BC AT,400 4BC AT x OAI 397744 36 250/264 .435/.435 400 2BC 393964 52 278/282 .430/.432 330 4BC ST, 425 ex. S/F, Toro 396190 50 286/280 .472/.461 425 Starfire, Pol. 396961 55 281/282 .472/.472 Toro 393859 58 286/286 .472/.472 400 ST ex. OAI 397328 82 308/308 .474/.474 400 OAI (W-30) 230328 82 308/308 .474/.474 400 OAI w/ 16 valve springs 1968 393859 58 286/286 .472/.472 400 ST ex. OAI 402486 48 262/274 .440/.440 400 AT ex OAI, 350 w/ 269 Pol. 400117 44 258/272 .435/.435 455 Irrig, Mar, hi-comp ex Pol., Toro, hi-perf. 400084 36 250/264 .400/.400 350 ex. OAI 402194 82 308/308 .474/.474 350 W-31, Hurst ex CAC Casting #389410 400165 57 285/287 .472/.472 455 Pol, Toro W-34, Hurst CAC 402569 108 328/328 .475/.475 400 OAI after 1-1-68 1969 393859 58 286/286 .472/.472 400 AT, W-32 OAI 400165 57 285/287 .472/.472 455 Pol, Toro W-34, F-85, Hurst, 455 Mar 4BC hi-perf 402486 48 262/274 .440/.440 3269 AT, 350 Pol. 402194 82 308/308 .474/.474 350 W-31 OAI 400117 44 258/272 .435/.435 455 ex. Pol., Toro, hi-perf. 402569 108 328/328 .475/.475 400 OAI ex. W-32 400084 36 250/264 .400/.400 350 ex. OAI 1970 393859 58 286/286 .472/.472 350 4BC ex. AT, OAI, hi-perf 400084 36 250/264 .400/.400 350 2BC, 4BC AT 400117 44 258/272 .435/.435 455 ex. Pol., Toro 400165 57 285/287 .472/.472 4257, 67, 4400 AT, Toro W-34 402486 8 262/274 .440/.440 455 Toro ex. W-34 402569 108 328/328 .475/.475 455 4400 ST OAI (W-30) 406768 68 294/296 .472/.472 455 4400 ST ex. OAI 402194 82 308/308 .474/.474 350 W-31 OAI 1971 400084 36 250/264 .400/.400 350 2BC, 4BC AT 400117 44 258/272 .435/.435 455 Toro w/2.73 axle, 455 ex 400 or Perf. Eng. 400165 57 285/287 .472/.472 455 4400 OAI w/AC, 4400 AT 402486 48 262/274 .440/.440 350 4BC ST,455 Toro w/3.07 409691 61 286/287 .474/.472 455 4400 ST, AT OAI ex AC 409717 32 250/264 .400/.400 350 5400 409759 68 294/296 .472/.472 455 4400 ST OAI (W-30) 1972 400084 36 250/264 .400/.400 350 L34, 350 AT L32, 33 All 400117 44 258/272 .435/.435 455 All 4BC AT, Marine LC 402486 48 262/274 .440/.440 350 F-85 4BC ST (L34), Marine 409691 61 286/287 .474/.472 455 L75 ST,L77 AT, Marine HC 409759 68 294/296 .472/.472 455 F-85, 455 ST OAI (W-30) 1973 400084 36 250/264 .400/.400 350 L32, L33, L34 400117 44 258/272 .435/.435 455 AT, Marine, 455 LC 402486 48 262/274 .440/.440 350 ST M15, M20 409691 61 286/287 .474/.472 455 4BC, L77, Marine 1974 409691 61 286/287 .474/.472 455 AG37, 455 W-30, Marine 455 (also #562302) 400117 44 258/272 .435/.435 455 ex W-30, Marine, 455 LC (Also #562303) 400084 36 250/264 .400/.400 350 (Also #562299) 1975 550638 28 242/250 .396/.400 260 400084 36 250/264 .400/.400 350 (Also #562299) 400117 44 258/272 .435/.435 455 (Also #562303) 409691 61 286/287 .474/.472 455 Marine (Reg.) 402486 48 262/274 .440/.440 350 Marine 409759 68 294/296 .472/.472 455 Marine Hi-perf. 1976 550638 28 242/250 .396/.400 260 400084 36 250/264 .400/.400 350 402194 82 308/308 .474/.474 455 Marine Hi-perf. F.P. 409759 68 294/296 .472/.472 455 Marine Hi-perf. 409691 61 286/287 .474/.472 350 and 455 Reg. Perf. Marine 400117 44 258/272 .435/.435 455 All, Irr., ex Marine 1977 562298 52 256/277 .247/.250 260 (thru 1982) 562299 36 250/264 .400/.400 350, 403 (thru 1980) 562301 68 294/296 .474/.472 403 Hi-perf. Marine thru 79 562302 61 286/287 .472/.472 350, 403 Reg. Perf Marine, ST thru 79Notes: Overlap is in degrees.
Olds rates duration at zero lift, while most cam manufacturers rate duration at .050" lift.
ST = standard trans
AT = automatic trans 2BC/4BC: 2 or 4 barrel carb
OAI = outside air inductionRoller lifters and cams were in all 1986 and up 307's, and most 1985 307's. 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.
[ Thanks to Greg Beaulieu, Tom Lentz for this information ]
A source for OEM carbs is at http://www.blake.com/oemcarbs/
Decoding Q-jets
As for a quick decode, conside Q-jet model number 17056259. Q-jets all begin with either "70" or "170", indicating a Rochester product (the "170" carbs are the newer ones, usually post 1974, though trucks used the "70" carbs until the 1980's; big difference is that the primary rods don't interchange between these two series carbs).
The next two digits indicate the year. Actually, the "6" is the last digit of the year, and the "5" is just different from the "2" that you would find in that place on a 1966 Quadrajet (I believe the 1986 would probably have a "7" in that place)
That leaves the last three digits, which usually distinguish the particular application of the carb for that year. The second to last digit usually indicates the manufacturer, with "5" being Olds (but just like that i before e, except after c thing, there are exceptions, especially in the mid-'60's). For example, most 350 4bbl Olds carbs ended with "250", and the Toronado engines ended with "252" for a long time. The standard big-blocks had the "251" carb, and the 442 and W-31/W-30 carbs would end in "254" to "259". No, this example is not a 1976 W-30 carb, though.
After 1974, to meet the more stringent emissions requirements, makers specified specific carbs for engines in particular models. So while every 1971 350 4bbl carried the carb # 7041250, in 1976 there were different numbers for the Cutlass carb, the Delta carb and the Omega carb.
As to whether it's a good choice for a performance buildup, it's not a *bad* choice, though I know I have built up a better selection of the "70" series primary rods than of the "170" series rods. Whatever you use it for, you'll likely have to rejet it and use different rods; with the "170" series carbs, GM seemed to favor larger jets, but thicker primary rods, which netted less fuel flow. Jets and secondary rods will interchange between series.
A few Carter Spreadbores ended up on some Cutlasses in the early 70's. Rumor has it that Rochester could not produce the amount of Q-jets needed so they subcontracted Carter to "pick up the slack" . You can id one of these pretty easily. On the side of the carb it will say Quadrajet by Carter instead of the usual Rochester Quadrajet.
[ Thanks to Jeff Easton, Bob Barry, Chris Smetana, Steve for this information ]
Carburetor Jets and Metering Rods
Here is a list of the carb #'s, along with the #'s for the jets, primary rods and secondary rods. These are the #'s from the AC-Delco manual, so they are only as accurate as that is. Also beware that I am just copying what is in the book(s); thus any errors or inaccuracies there are here as well.
Especially interesting are the 1970 W-30 and W-31 with manual transmissions; it looks like those Quadrajets used the 2-bbl jets with no metering rods! (this has been confirmed by some original W-30 owners; note this is only the 1970 M.T. applications)
Year & Application Carb # Main Jet Primary Rod Secondary Rod 1966- 400/425 M.T. 7026250 7031971 7031844- "44" 7033655- "AU" 330 M.T. 7026254 7031971 7031844- "44" 7033658- "AT" 400 A.T. w/o A.I.R. 7026256 7031971 7031844- "44" 7033655- "AU" 330 A.T. w/o A.I.R. 7026255 7031971 7031844- "44" 7033658- "AT" 1967- 330 7027036 7031971 7031844- "44" 7033658- "AT" 330 w/ C.C.C. 7027135 7031971 7031845- "45" 7033658- "AT" 330 w/ A.I.R. 7027153 7031971 7031845- "45" 7033658- "AT" 400/425 w/o A.I.R. 7027156 7031971 7031844- "44" 7033655- "AU" 400/425 w/ A.I.R. 7027157 7031971 7031845- "45" 7033655- "AU" 400/425 w/ C.C.C. 7027032 7031971 7031845- "45" 7033655- "AU" 400 M.T. w/O.A.I.(5) 7027156 7031971 7031841- "41" 7033655- "AU" 425 Toro w/o A.I.R. 7027131 7031971 7031844- "44" 7033655- "AU" 425 Toro w/ A.I.R. 7027130 7031971 7031845- "45" 7033655- "AU" 425 Toro w/ C.C.C. 7027132 7031971 7031845- "45" 7033655- "AU" 1968- 350 7028250 7031971 7034849- "49B" 7033658- "AT" 350 w/ W-31 7028255 7031974 7034849- "49B" 7033658- "AT" 400/455 7028251 7031971 7034849- "49B" 7033655- "AU" 455 Toro 7028252 7031971 7034849- "49B" 7033655- "AU" 400 W-30 7028254 7031975 7034849- "49B" 7033655- "AU" 400 "442" 7028253 7031972 7034849- "49B" 7033655- "AU" 1969- 350 7029250 7031970 7034849- "49B" 7033658- "AT" 400/455 7029251 7031970 7034849- "49B" 7033655- "AU" 455 Toro 7029252 7031970 7034849- "49B" 7033655- "AU" 400 M.T. 7029253 7031972 7034849- "49B" 7033655- "AU" 400 W-30 7029254 7031975 7034849- "49B" 7033655- "AU" 350 W-31 7029255 7031974 7034849- "49B" 7033655- "AU" 1970- 350 7040250 7031970 7040701- "52C" 7033658- "AT" 455 7040251 7031970 7034849- "49B" 7033655- "AU" 455 Toro 7040252 7031970 7040701- "52C" 7033655- "AU" 350 W-31 (6) 7040255 7002657 - 7033655- "AU" 455 "442" MT 7040253 7031969 7040699- "48C" 7033655- "AU" 455 W-30 M.T. (6) 7040256 7002658 - 7033655- "AU" 455 W-30 A.T. 7040258 7031969 7040701- "52C" 7033655- "AU" 455 W-33, 442 A.T. 7040257 7031969 7040701- "52C" 7033655- "AU" 1971- 350 7041250 7031970 7034849- "49B" 7038256- "AS" 455 7041251 7031970 7034849- "49B" 7033104- "AK" 455 Toro 7041252 7031970 7034851- "51B" 7033549- "AX" 455 M.T. 7041253 7031969 7034849- "49B" 7033655- "AU" 455 A.T. 7041257 7031969 7034849- "49B" 7033658- "AT" 1972- 350 7042250 7031969 7034850- "50B" 7045778- "CG" 455 7042251 7031969 7034850- "50B" 7045779- "CH" 455 Toro 7042252 7031969 7034850- "50B" 7045779- "CH" 455 "442" 7042253 7031969 7034847- "47B" 7045779- "CH"Notes:
The following abbreviations are used:
A.I.R. - Air Injection Reactor C.C.C. - Climatic Combustion Control O.A.I. - Outside Air Induction M.T. - Manual Transmission A.T. - Automatic Transmission Toro - Toronado W-30 - High-performance big-block engine W-31 - High-performance small-block engine (1) Except for the applications otherwise noted, the carb listed was used in all applications of that motor. The usual exceptions are the specific engines used in the 442 and Toronado models.
(2) The last two digits of the part number designate the size of the jet orifice in thousands of an inch. Thus, a jet with the part # of 7031971, has an orifice of .071", and is stamped with a "71".
(3) The last two digits of the part number usually designate the size of the largest portion of the tapered shank of the rod in thousands of an inch; Thus a primary rod with the part # of 7031844 has a taper of .044" at its largest point. This two-digit number is also stamped on the rod. After 1968, the metering rods had a double or triple taper, and had a "B" or a "C" suffix stamped on the rod, respectively. These triple-taper rods, however, do not have a part # corresponding to the size of the taper, although the stamped number on the rod does correspond to its diameter.
(4) The secondary metering rods are stamped with a two-letter code. A guide to the comparative dimensions of these rods can be found on pp. 152-153 of Doug Roe's Rochester Carburetors.
(5) The O.A.I. carburetor had the same part # as the standard manual transmission 442 engine carburetor, but had different primary metering rods.
(6) Note that the W-31 and W-30 carburetors apparently used 2-bbl jets with NO primary metering rod, and thus no power piston. If any owner of one of these carburetors could confirm this, I would appreciate it (I thought it was a typo at first, but it is specifically listed this way for both W-31 and W-30 applications).
The Doug Roe book on Rochesters, in the chart showing all the primary metering rods, shows the only triple taper rods ever made were rods 7040699- 48C and 7040701- 52C, and these were used on 1970 Oldsmobiles only. Olds was also the only one to use the triple rods.
The triple taper rod was and attempt to fine-tune the fuel curve more precisely than the dual-taper rods, introduced in 1968, allowed. I guess it didn't work well enough to justify the expense, since they went back to dual-taper rods the very next year. It seems that the carb section of the Olds engineering department was getting a lot of overtime calibrating the 1970 units, what with the triple-taper rods and the no-rod "W" units. Apparently, not everybody went to the dual-taper rods in 1968, however.
Mondello's tech guide states that the replacement of the primary metering rods is unnecessary, since they all have the same size small-end. While this is true, it is only applicable for WOT use. At part-throttle, the taper of the rod is somewhere in the jet, and it's this taper that determines part-throttle response. You know, when you want to merge or accelerate like a responsible citizen; not too cool to drive at WOT all the time when you're taking your family out for dinner. Therefore, for street use you do want to select a primary metering rod that will complement your setup.
[ Thanks to Bob Barry, Jeff Easton for this information ]
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