There was post about this tucked away in another thread somewhere, but I can't find it. I have about 10" of vacuum. If I take a vacuum gauge and run my car at WOT, what vacuum reading would indicate my carb is a tad too small? what should be normal?

For fuel delivery, I'm getting 5.5lbs. if I run it at WOT, at what reading would indicate I dont' have enough GPH?

When I was on the dyno we installed a vac gauge to watch restriction. The problem is you won't see it till max rpm.

Anything over 1". 5" of vacuum is a serious restriction.

4bbl carbs are flow rated at 1.5" Hg depression (vacuum). If you're pulling any more than about double that (3" Hg) in the upper RPMs wide open, you can pretty much take it to the bank it definitely wants a larger carb. For a race engine you don't even want it anywhere near that high.

Just make sure you aren't pulling too much vacuum becuase of something simple- throttles that aren't FULLY open or a restrictive air cleaner assembly.

Wow, gonna be hard to watch the road and the vacuum gauge at WOT @6000RPM.

How about knowing if you have enough fuel pump? How many pounds of pressure will the gauge say at WOT if I need more GPH?

Shawn.. To tell you the truth bud, you really don't want to any more than .5 psi drop at the top end of each gear and top end at the stripe for best results on a street/strip combo..

If it's more a street ride though.. I would say about 1.5 psi drop MAX

shawn, on the fuel psi,, you'd like to see it stay level at 5-6psi. across the power band to full throttle at peak max rpm. but if it dips below 3psi,, you better get out of the go pedal till you figure out if it's the pump,, or a restriction in the flow path somewhere. hope it helps.