I really need your guys help. I recently built a 400hp 350 sb. I topped the engine with a Peformer RPM intake and 1407 Performer Carb. My problem has two parts. First, the engine would not idle with the choke plate closed- so I took the choke off the carb. From there the car would idle, and I then proceeded to set the idle mixture. With the engine warmed up and running I turn the screws in until I hear the motor begin to stumble and I back them out 1 1/4 turns. After doing boths screws I set the idle. The engine has an Isky cam with 280 degree of running duration that produces approx 7 inches of vacuum at idle. Heres my problem. I went out to test drive it today and the engine bogs and stumbles when I accelerate from idle. The car runs fine above 2500 rpm, but below that, it stumbles and even backfires sometimes. And if I floor it off idle, the motor almost stalls for a second then quickly jumps back to life. Also, if I take a quick U- turn then the car almost stalls. I dont know where to go from here. I need to know if I should richen or lean the mixture, change rods or springs, or change the accelerator pumps squirt, or adjust the float level. Please help. I need to get my Chevelle on the road, its my daily driver.
70 Chevelle 350ci/th350 10bolt Go Earnhardt Jr.!