Q-Jet

[D S.]

What is the correct number for a Rochester Q-Jet for a September 1971 built engine in an October built 1972 Corvette LS-5 with TH400? Would the Julian date be something like 1240?

Thanks,
Scott

[Joe L.]

Re: Q-Jet

What is the correct number for a Rochester Q-Jet for a September 1971 built engine in an October built 1972 Corvette LS-5 with TH400? Would the Julian date be something like 1240?

Thanks,
Scott

Scott----


GM #7041204. As far as date coding, yes, something like what you suggested.

[D S.]

Re: Q-Jet

Thanks, again, Joe. I thought it was maybe 7042216 then 7042204 or maybe this or that and then I said to heck with it...ask the TDB.

[William C.]

Re: Q-Jet

At least according to the JG, the 7042216 would be the correct unit for a 1972 model year Corvette. the '204 is the '71MY number. As the carb was part of the emissions cert syatem, the '72 carb would have been use from the start of '72 production.

[D S.]

Re: Q-Jet

Oh, boy...confusion sets in here. So what you are saying is that a 1972 Corvette engine built in September 1971, body build in October 1971 would have a carburetor number of 7042204? Would I not be looking for a late build 1971 204 or would the Julian date begin in September 1971 for the model year 1972 as 2001? Or would it be a late 1971 7041204 with a Julian dates 1240 to 1365?

[William C.]

Re: Q-Jet

No Confusion, you need a "216" carb for a 1972 model year 454 corvette, regardless of when the engine was built or when the car was assembled. BTW, the carb was installed at the assembly plant during the car build, so the carb to engine build date relationship is nonexistant.

[D S.]

Re: Q-Jet

Thanks for that information. Based on what you are telling me the 7042216 is correct upon the start of the 1972 model year assembly. Then if the build date of the 1972 Corvette is October 1971 what would the Julian date be to be correct to the car? Anywhere from 1120 (6 month window) to the exact build date of the Corvette? Are you saying that the engine, which was built in September, can have an October carburetor? Is this true in all model years of C-3s? Can I tell a 1970 Corvette owner who has a January 1970 build date that his Q-Jet can be a January carburetor and be okay with NCRS judging?

[William C.]

Re: Q-Jet

Allowing for a reasonable few days of transportation from Rochester NY or Bay City, Michigan to St Louis, the answer is yes, the carburetor was installed at the car assembly plant, as spelled out in the assembly manual, so with the exception that both had to be built before the car was built, there is no direct relationship between the engine assembly date and the Carburetor build date. As an example, I once owned a 3-star unrestored 454 with A//C 1972 car built the last week of production, and the carburetor was dated December of 1971 as I recall.

[Joe L.]

Re: Q-Jet

Thanks for that information. Based on what you are telling me the 7042216 is correct upon the start of the 1972 model year assembly. Then if the build date of the 1972 Corvette is October 1971 what would the Julian date be to be correct to the car? Anywhere from 1120 (6 month window) to the exact build date of the Corvette? Are you saying that the engine, which was built in September, can have an October carburetor? Is this true in all model years of C-3s? Can I tell a 1970 Corvette owner who has a January 1970 build date that his Q-Jet can be a January carburetor and be okay with NCRS judging?

Scott-----


I'm terribly sorry. For some reason I thought you had and were talking about a 1971 Corvette with LS-5. I see now that your original post clearly says the car involved is a 1972. For a 1972 LS-5 with M-40, the 7042216 is the correct carb. No confusion or doubt about that, at all. The fact that the car was built in 1971 makes no difference.

[D S.]

Re: Q-Jet

No problem, Joe. Bill Clupper gave me a course in Q-Jet 101 today. After I read his responses I kinda thought you might have misread my post since I made references to both 1971 and 1972. One other question: Carter or Rochester for 1972 LS-5s? If Carter then the date code is a MY only instead of Julian?

Thanks to both you and Bill.

[Joe L.]

Re: Q-Jet

No problem, Joe. Bill Clupper gave me a course in Q-Jet 101 today. After I read his responses I kinda thought you might have misread my post since I made references to both 1971 and 1972. One other question: Carter or Rochester for 1972 LS-5s? If Carter then the date code is a MY only instead of Julian?

Thanks to both you and Bill.

Scott-----


During the early C3 period, Carter did manufacture some of the carburetors for Rochester. However, I do not know if they made the specific part number involved here or, if they did, whether they were the only source.

However, I would not be concerned. If you are looking for that specific carburetor part number and you find one properly dated, that carburetor could have originally been installed on the car. So, whether it's a Rochester or Carter-manufactured carb, it makes no difference.

[Terry M.]

Re: Q-Jet

One other question: Carter or Rochester for 1972 LS-5s? If Carter then the date code is a MY only instead of Julian?

Thanks to both you and Bill.

Carter made Rochesters are dated with a letter for the month (there is a recent post about that someplace on the board) and a single digit for the calendar year.

BTW: ALL the information you have asked about 1972 Carburetors is in the TIM&JG, available form the sponsor of this site. Check it out.