I have a 1974 Pontiac Lemans coupe with original 350 Pontiac V8 motor, 350 gearbox and 2 barrel rochester carburettor. The only mods are oversized valves for a little bit more oomph, K&N air filter, straight through exhaust with just resonators and recently put in new hydraulic lifters on the passenger side bank as these were worn.
My problem is that although the car has been garaged for 6 months I managed to get her running in no time, but she has a backfire through the carburettor and when I accelerate hard from standstill she like wants to die on me and then suddenly comes to life. Her stock specs are between 28-32 degrees for the dwell angle and timing must be 12 degrees BTDC. I had to adjust the timing to 16 degrees to try and compensate for the backfiring which has helped a bit but not much. Even with the old lifters clucking away she did not have this backfiring problem and there is even a little bit of smoke coming out the exhaust when I rev her up in park. Please help, I am getting gray hairs!
My problem is that although the car has been garaged for 6 months I managed to get her running in no time, but she has a backfire through the carburettor and when I accelerate hard from standstill she like wants to die on me and then suddenly comes to life. Her stock specs are between 28-32 degrees for the dwell angle and timing must be 12 degrees BTDC. I had to adjust the timing to 16 degrees to try and compensate for the backfiring which has helped a bit but not much. Even with the old lifters clucking away she did not have this backfiring problem and there is even a little bit of smoke coming out the exhaust when I rev her up in park. Please help, I am getting gray hairs!
Dec 12, 2006 at 3:34 AM