I have a 600 square bore vac secondary holley on a virtually standard 302 Cleveland. I know the carb is a little on the large size for a 302 but as it's a really good carby, I would like to keep it. The only problem is it is running a bit rich. Float levels are spot on. Would it run leaner with smaller jets and if so, can someone suggest a good jet and or power valve size that would suit a 600 on a stock 302.

The power valve might not be real good, replace it with an 85 power valve, and the jets should be 64's. I have found replacing the accelerator jets'nozzles with an item from a 350 ( 4778 ) Holley work better. Make sure the dizzy is in good nick too, it also helps......flat spots and stuff.

Thanks mate, I'll give that a go. Dizzy is good. No flat spots at the moment, just too rich. Lots of black around the pipes and fumey.