Hey, Ive got a holly 750 4160, and Im wondering if its too much for my car? Ive got an early- 70's 350 basically stock, and whjen I floor it im not getting the acceleration I want. Its really rich, but If I try to lean it any further I get a bad idle. Also, when I gun it from idle, it backfires until I let off. Im having trouble paying for all the gas Im using, and was wondering if a 600 4150 would help the car run smoother until I can build up a new engine?

 

If memory serves me early 70's 350 engines w/ a barrel came stock w/ a q-jet that was rated at 750 cfm. I don't think that you are over carbed, just not tuned right. First i would check your timing as thats prolly what the backfire is from. Once the timing is where its supposed to be then i'd worry about the carb. Get a vacume gauge and and adjust your carb till your pulling as much vacume as possible. Set your idle to somewhere between 600 -750 rpm. That should get you in the ballpark for troubleshooting. I would prolly adjust your accellorator pump as well. Then see what it does. If its too lean, go 2 sizes bigger on your jet sizes. If its too rich, go 2 smaller.