Re: Holley carb power valve questions
 

I use a "window" type, 8.5 in the primary, with the secondary pluged. If you go this route you will have to increase the secondary jetting. I believe I am went from 76s to 84 jets. Seems to work great.

Re: Holley carb power valve questions
 

If you've got 13 inches at idle you don't need a 6.5... try some 10.5's.