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I need some help from one of you Carburetor guru’s, Here are my problem. I have a 72 C3 with stock 350 and a manual transmission, when checking to see if I needed a new air filter I found a lot of soot on the underside of the cover as well as the inside of the carb so I was going to rebuild the carb and adjust the air fuel mixture. After looking up the numbers on the Rochester Quadrajet it appears to have been swapped out with the carb from a 77 Oldsmobile with an automatic transmission the numbers on the carb are as follows 17057258 3046 APY. After inspecting the carb I noticed that the rod that should be connected to the choke coil lever has been tie wrapped off as shown in the photo also the choke coil lever does not rotate. Why should someone do that and what would cause the choke lever to get stuck any help with this would be greatly appreciated.
From: At my Bar drinking and wrenching in Lafayette Colorado
Your carb is a complete, "frankencarb" pieced-together piece of junk that has been assembled from various random parts from different years, makes, and models (both 4MV and M4M) Q-Jets, none of which are compatible with each other. It is beyond salvation, and needs to go in the trash can. Find a good, used, unmolested, rebuildable Q-Jet for your car that is the correct year and model carb for your application. The exhaust gas reversion sooting up through the carb is indication of timing problems with your engine - usually a bad case of retarded timing.
The 1972 Q-Jet looks like this. Compare to what you have:
Start looking for a good, rebuildable core. There is no point at all in attempting to do any "adjustment" or "repair" work to the pile of parts you currently have.
Lars
I'm no Q Jet guru but, essentially the zip tie has "wired the choke open". You have a non functioning choke. I'm sure others will comment on your other questions.
From: At my Bar drinking and wrenching in Lafayette Colorado
Your carb is a complete, "frankencarb" pieced-together piece of junk that has been assembled from various random parts from different years, makes, and models (both 4MV and M4M) Q-Jets, none of which are compatible with each other. It is beyond salvation, and needs to go in the trash can. Find a good, used, unmolested, rebuildable Q-Jet for your car that is the correct year and model carb for your application. The exhaust gas reversion sooting up through the carb is indication of timing problems with your engine - usually a bad case of retarded timing.
The 1972 Q-Jet looks like this. Compare to what you have:
Start looking for a good, rebuildable core. There is no point at all in attempting to do any "adjustment" or "repair" work to the pile of parts you currently have.
Lars
Thanks Lars, I greatly appreciate the advice and photos, I have found a few things on this car that were not done quite right that I have had to fix.
I’m glad I waited before waisting my money on rebuilding this one.
I have the carb your looking for. 7042202. It was Tuned By Lars a few years ago for my friends Camaro. That car got wrecked last December, rear ended by a cement truck just outside of Denton Texas. My friend Lou and I stripped the car for what it was worth, sold the parts and the engine but I kept the Q-jet because I still had all the paperwork from Lars. It was a driver/beater Camaro but it ran great and was a blast to drive. PM if interested. Id like to see it go to a good home.
Was that George Montany's carb..? My test data sheet shows it ran pretty good...
Thats the one. Its only got about 2500 miles on it since the rebuild. We made a small adjustment to the secondary air valve spring and the idle adjustment and that was it. That car ran great. The 186 heads and the carb are all that remain.
From: At my Bar drinking and wrenching in Lafayette Colorado
That was in 2024. It was the second carb I built for George - I did a 1973 L82 Vette carb for him, too. Kinda' cool to see these carbs are still around and running well.. It would be great to have the carb live on with someone who would enjoy it.
Lars
Thanks to everyone for your input, found a rebuilt carb off a 72 locally that I will pick up tomorrow and install this weekend along with checking the timing.
Hopefully that will solve my carburetor issues, Thanks again everyone
Some people have difficulty listening, obviously this guy with the carb problems hasn’t spent much time reading any posts on the Forum. I have a car show buddy that is the same way, he has thrown more money and time trying to restore/repair his Quadrajet, with extremely poor results. I don’t think he will ever give up, no matter how many times his engine fails to start, it gets hot. End of Story.
Some people have difficulty listening, obviously this guy with the carb problems hasn’t spent much time reading any posts on the Forum. I have a car show buddy that is the same way, he has thrown more money and time trying to restore/repair his Quadrajet, with extremely poor results. I don’t think he will ever give up, no matter how many times his engine fails to start, it gets hot. End of Story.
Sneak into his garage and fix his timing for him. I bet he'll fight you if you suggest that GM stock timing is no longer best practice.
Thanks to everyone for your input, found a rebuilt carb off a 72 locally that I will pick up tomorrow and install this weekend along with checking the timing.
Hopefully that will solve my carburetor issues, Thanks again everyone
At least post a photo. Did you email @lars for his timing and Q-Jet papers? Everyone on this Forum is trying to help you, but the quickest path is unlikely to lead to success with a classic Corvette.
Rochester Carb problem
