hey,

MY holly 750 is running extremely rich, at WOT the gas smell is unbearable and it leaves black spots under the exhaust pipes. I dont know anything about holleys as this is the first one Ive ever used. Anyhoo, I was wondering if anyone knew how to adjust the air feul mixture. If that doesnt work, what jets should I use? Im running a 350 ci engine at about 40 feet above sea level. Also, could the power valve be at fault? If so, how do I replace it?

Thanks!

 

Froggy,

What model Holley are you using? There are lots of possibilities, including a stuck/blasted power valve, poor jetting, metering plate leaks, either float adjustment, high fuel pressure, etc. Look on the left (driver's) side of the front of the air horn, and you should find a model and part number stamped there.