Hi, I have a 1958 Cadillac Fleetwood and just had the Rochester 4 gc 4 barrel carburetor professionally rebuilt. My mechanic installed a new heat insulator and 2 gaskets under the carb. The car engine ran very poorly with all 3 of these gaskets. He removed the heat insulator and installed the 2 gaskets ONlY under the carb. Then restarted the car and it ran well but would NOT IDLE at all! He sprayed around the carb. With carburetor cleaner while the engine was at fast idle and there was no sign of the engine speeding up ,which I understand would mean no air leak. When he removed the carb. for a rebuild there was old red gasket maker goop on both sides of the old gaskets,apparently to keep any air out? I do not think I should install gasket maker goop with the new gaskets and insualtor. My mechanic also just installed a new timing chain and gear, water pump and Pertronix ignition. Is there a vacuum leak or? areas that he should check? Please help as he has had my car for 4 months and I want to get it back in my garage before salt hits the roadways. Thanks, Al
One major question: how was your engine running BEFORE this mechanic dived into it???? You appear to indicate that the carburetor was the LAST component he rebuilt and he installed and then started the car. Did the car run reasonably well before he tackled the carburetor, or as he repaired and replaced parts, did he attempt to get the engine to run properly. He might have rebuilt your carburetor incorrectly, OR he may have made errors on any one or a combination of the other components he worked on. You need to reconstruct your narrative more precisely. Also... sounds like he's done a bunch of work for you, and you're on the back burner now. I feel your pain. James
From here this is almost impossible to diagnose, vacuum leaks are the first thing to look for, no sealer should be used on any carb or base gaskets, that is just a patch for the root cause. Only proper onsite diagnosis is going to correct this problem. The vacuum leaks should be tested at the lowest rpm.
Disconnect all vac lines and plug them------ including the one for the power brakes. People forget about the brake line.
That actually happened to me last weekend. Brake booster check valve went bad.
Be sure to plug the lines at the source, not at the end of the run.
Jeff
Hi
I guess the 58 is similar to the 68 in the way the heat is transferred to the carburetor.
The usual setup is manifold, gasket, heat shield, carburetor.
I had mine configured with manifold, gasket, heat shield, gasket, carburetor and it ran fine. I then removed the second gasket between heat shield and carburetor and it ran the same.
However, if you leave the heat shield away the engine will not idle right. This is even stated in the shop manual!
Best regards,
Nicolas
I believe the heat shield was only used on the Carter not the Rochester carburetor
Correct.
If it ran "poorly" and "would not idle at all" the gaskets are not the issue.