Holley Jetting Problem
 

I've got a 468, intercooled, B&M 420, two 650 Holleys, 8 pounds of boost...last season ran great with the current jets/carb settings...minimal transon soot. Over the winter I freshened it up, installed one size smaller cam shaft and dropped the boost to 5psi...now the whole back of the boat is always covered with soot. I know it's not just from a rich idle, because it's from top to bottom like when your up and running. The carbs aren't boost referenced and the power valves are not blown....

Anyway my question is...is dropping just one jet size going to make that big of a difference...or should I drop it 2-3 sizes??? Currently I've got 84s on the secondarys and 78s on the primarys?? I just don't want to tare it apart three or four times to get it right...maybe just once or twice..

Thanks in advance. Gary

TTT

I'd start with 2,,, but I'd rather tear it apart 5 times, then go to much, lean it out and hurt something !!!!!!!

P.S. Pull a plug and read it after a long hard run,,, dont rely on transom soot for mixture.

With the new leaded fuels and additives I have found it very hard to get accurate plug readings. I'd expect you will pull a plug and think it is lean..... When fuel was leaded I looked for a slightly tan electrode, but now with new unleaded fuel I only find a small tan ring around the end of the electrode when it is running correct. I stick to a dyno.