Poor idling SBC
 

I have a pair of them and they have Holley 600cfm carbs. Engines are fresh. 1 Carb is brand new. They have a hard time holding an idle and won't at all when poped into gear. I'm running 36 degree timing at 3000RPM. No vacum lines used on my set up so thats one thing thats not a problem. If it were an engine vacum issue, where would the most likely place for it to leak. The engines are fresh with all new gaskets. I do have a carb spacer. Do they ever start causing problems over time? Any help would be appreciated. Docking this thing is a real pain in the A$$.

Chris

Is it a stock marine carb? Even if it is not the carb has two ports that need to be blocked off, if they are not blocked you have a vacuum leak. The timed spark port and the manifold vacuum port.

If the above is good, then check the idle mixture screws. As a starting point they should be 1 1/2 turns out. More than likely they are like 3/4 - 1 turn out. Keep adjusting till you get the best idle.

The spacer should be fine, assuming the carb linkage is not hitting the spacer causing a leak.

How do they run off-idle?

what cam are you running ?? if it's fairly radical, you may have run your dist locked or very little advance to clean up the idle. you said you are running 36 total, whats the initial ? try setting the intilal at 30(don't run it that way) to see how the idle is...I've had to to do this on mant applications...Rob