My wife's '73 has an '80 302, .30 over, stock heads and bottom end, a holly 650 DP, a stealth intake, hedman long tube headers, and a mild comp cam. This car is driving me nuts! It's runs exteremly rich. It will foul out a new set of plugs in just a few minutes. We have checked the timing, the ignition, and even tore the holly apart (even though it's brand new). Any ideas?
Way too much carb for one thing. Probably needs to be jetted down. I had the same probs on a 302 I had. Switching to a 600 Vac Secondary cured it right up.
try adjusting the float levels as well, and make sure the float needles are seating. if the carb is working correctly, im with stockhatch on that. I switched to an edelbrock though.
Your carb is NOT too much. It is far from an economy carb, but it is sized right. You just need to take a deep breath and read up voraciously on Holley tuning. Once it is tuned correctly, it will run great for a very long time. What tranny do you run? What gears do you run? Those play to the size squirters, pump cams, and diaphram volume you need. General areas to check: Float levels (sight plugs on the side of each bowl... I use clear plugs) Fuel pressure (unlikely, but can override the floats) Sticking choke (obvious, but I had to throw it out) Ruptured or malfunctioning power valve Misadjusted pump linkage Jet sizes Other considerations: Too large accelerator pump 5cc vs 3cc Too large squiters for gear ratio Check valve missing from below squirters (allows engine to suck fuel through squiters) Idle mix screws Age of carb (you say new, but when was it built... power valve protection has only been standard for a decade or so) Give it a chance, and read, read, read... everything you can about Holleys, your model in particular. They are the absolute best carb, but you have to do it right. Whatever you do, don't go to an AFB (Edelbrock) unless you just want an economy part. Good luck Dave
blackpony; Like Dave said, check all that...I have a 600 vacuum sec. and the power valve ruptured, and it caused all kinds of heartache. Ran rich, stalled and chugged when going slow, belched black smoke. Hard to believe that little valve can cause all that. Good luck!
