Power Valve Selection: The Definitive Answer

12many said
Quick (long version!) update on things. With the 10.5" PV installed, doing calculations and settling on jet selection (73 primary, 83 secondary) with ootb 31/35 clusters and 1st hole pink cams, fixed .052" PVCR) I now have it in the ballpark better than previously. Idles good in park, gear, revs crisp and quick, vacuum 14"/10" respectively, a/f readings low/mid 13's (which I can tweak further) with easy primary only running up the rpm's with no pump shot and cruising up to over 3000 rpm readings from upper 13's up to a few ticks over 15. Heavy primary acceleration with the PV opening drops it to upper 12's (and it pulls stronger much better than before, WOW would be the best description . And then just doing some WOT runs the response etc is just as good, Upper 12's on gauge. Only niggle is the slight lean hesitation at tip-in, will try pump shot, look at the feed/bleed tuning. Still more to tweak, but I "could" live with it as is! Running the 10.5" with my 18" +/-cruise vacuum readings....WOW.:thumbsup:

THANK YOU for doing all the work for the naysayers and doubters. I learned the PV opening lie from a guy WAY smarter than me decades ago. I've been trying to help guys correct their stuff since then but it's damn hard to convince some people that Holley was dead wrong. So we're the clowns who repeated the lie in their carb books.

Wait until you start trimming the main jet down to get the cruise A/F ratio as lean as it will take without a lean miss, and then you correct WOT fuel with the power valve channel restricters! You'll get incredible fuel mileage, it will make more steam in the middle and still roar on top.

Thanks for doing the dirty work.

Hopefully, more than one or two guys will revisit their tune ups and get the benefit of a correctly times power valve opening.