Question on Carter/Rochester Carburetor

[imported_48Rdmstr68Skylrk]

I have a "Quadrajet" carburetor that is stamped "MFD. by Carter Carburetor for GMC". The numbers are as follows: 17080292 and 2069 CKY.

The best I can figure from my limited research is that this carburetor was made by Carter for Rochester. The 170 means it was made afer 1976. The 80 means it was for a 1980 vehicle. The 2 means the carb is a "49 state Q-jet". The 9 means it is a "special" unit - not belonging to Buick or the other 4 GM divisions. The last 2 means it is for a vehicle with auto tranny. The second line of numbers is the 206 th day of 1979 - or July 25, 1979. The CYK is the plant code which I can't find a listing for.

So my question is, can anybody tell me what the "Special" division of GM is and what the CYK plant code stands for, and if my other research above sound correct? Is this an after market unit made for the Hot Rod market?

Thanks in advance for any info you can provide.

[NTX5467]

Some thoughts . . .

Considering the GM part number for a 1978 Chevy 305/350 QJet was 1705____, your suspicion of a 1980 model year carb seems ballpark. Probably the best way to search for the vehicle application would be in a carb kit listing. By 1980, it seems that there were starting to be some electric choke assist items and a few other electronic gizmos sneaking into the product mix?

GM-Rochester Products did use Carter for a sublet manufacturer in some cases back then, while Carter was still Carter and not an almost "dead" Federal-Mogul property. I was thinking most of those were a good deal before 1980s, though. They were built to the same blueprints as an "in house" Rochester carb, but I recall hearing that they were not of the same build quality as the GM-Rochester carbs and were somewhat "trouble prone". In that case, "Made for GMC" would mean "General Motors Corporation" rather than "GMC Truck and Coach Division", I suspect.

I recall no GM-Rochester carbs for the aftermarket or non-OEM applications back then. GM-Rochester did build carbs for various non-GM entities over a period of time, though, as Chrysler used QJets as replacements for Carter ThermoQuads when Carter stopped doing OEM carbs in the 1980s. Seems like there might even have been a year of so of them on late 1960s Ford big V-8s? Still, no non-OEM applications per se.

One possible reason for there not being any non-OEM applications was the pretty specific jetting the QJets had. They were highly adaptable (primary metering rods, secondary metering rods, primary power piston springs, secondary metering rod hangers, primary jets, choke pull-offs and vacuum break setups) to a very wide variety of engine and fuel curve requirements so they were not really "universal" in the same way as a Carter AFB or some of the Holley 4bbls can be. Not that they probably could not have done some "hot rod" aftermarket versions, but with all of the GM business they had anyway, there might not have been enough time and research money to do non-OEM items.

Just curious, though, whas was this carb desired to fit?

Take care,

NTX5467

[carbking]

The number in question is newer than our books, so cannot give a specific answer. However, the "special" simply meant not a normal GM line. This included Ford in the early 1970's among others, and especially marine applications (Chriscraft, Chrysler, Kiekhaeffer, etc.). These were O.E. applications, not aftermarket.

The Carter-built quadrajets were no different in quality than the Rochester-built quadrajets. This "urban legend" is easily understood. Carter charged GM based on the number of units built. There were far fewer "Stage 1 Buicks", "Ram Air Pontiacs", and "W Oldsmobile" cars built than the more common useage, and Carter would have charged more per unit for these items; thus Rochester, after the 1967 model year, built all the high performance units in-house. Those who continually search the core yard, junk yards, swap meets, etc. for items to resell learned this; and thus would not even look at the Carter-built Q-Jets. From this was developed the myth that the Carters were more trouble-prone.

Jon.

[imported_48Rdmstr68Skylrk]

I met an another Buick car enthusiast last month. I told him I have a 68 skylark convertible with 350-2 barrel and was thinking of converting to 4 barrel. He said he had this quadrajet and he just gave it to me - the very first day I met the guy!!! Great guy! As it turns out is is not right for my car. If I convert, it has to be the correct carb or I won't do it (I'm detailed oriented that way). So anyhow, I'll probably give the carb to my buddy (easy come ease go) who has a 69 Olds 442 W30. That car has been modified and he dosen't care about originality. Any thoughts on this unit bolting up and working for the 442???

[carbking]

Short answer: it probably won't work without MAJOR modifications.

Somewhat longer answer: any of the carbs for the W-series cars are somewhat on the pricey side. However, any carb from the same year, make, and engine (even if not a "W") would be infinately closer in calibration than a late 70's or early 80's smog unit. This assuming (not aways a good idea) that the throttle, choke, fuel, air cleaner, etc. would all hook up.

The most expensive carburetor anyone will EVER purchase is the incorrect for the application carburetor given to you by your neighbor!

Jon.