Power Valve Issue?

[gsharapa]

I've been down this road many times with big cam motors in Offshore boats and Cobras. If you have a big cam you have very little vaccume which is allowing the power valves to open and give your engine too much fuel. You were right on your assumption that going to 8.5 was the wrong direction. In the Fountain offshore boats I was running 2.5 and in my Cobra's with big cams 3.0 to 3.5. Drop the power valve from 6.5 to 5.0 and see if that makes a difference and down from there. They are cheap and easy to replace....good luck.

[cdnus]

I have a Pro Systems 950 HP on my 408/W ( I know, I know BIG CARB ) that,s what he built me when I gave him my spec's.
I had what sounds like the same thing you have. After trying numerous suggestions from helpful members & none solving the problem I put a lot of thought into it & concluded it was not transitioning correctly. Soooooo I started with decrease idle air bleed from .076--.073. Then increased idle feed restrictor from.035---.038. Much better but not quite there, still a very slight lean spot when breathing on the throttle @ cruise.
Then with everything set as good as I could get it I pulled the carb & checked the transition slot, YIKES!!! only .010 exposed.

I set the throttle so there was .020 exposed put it back on with no further adjustments---YAHOO-- it idles a little faster than I would like, but I can live with that because now I have instant response when I breath on the pedal @ cruise 1500-2300rpm. A/F will run from high 14's low 15's when cruising & drop to mid to high 13's when I even think about increasing throttle.

Hope this is of some help

Craig

I also run with a 02 LM1