Originally Posted by bowtie44s
I have a 6.5 power valve. I am pulling right at 20" at idle (yea, mild cam.) I have been watching the vacuum while driving. Cruising in OD i'm around 12-15". When I punch it, it quickly drops below 5 so I haven't noticed any problem with the power valve. I haven't watched vacuum with a load, only empty. I know quick fuel makes a 4 door high flow power valve. I'm not sure what I have, I never paid attention. I just checked it for tears and figured it was good. Is there another way to get more volume of fuel other than a "high flow" power valve? How would I know if I need more fuel on the power valve circuit with out an afr gauge? It doesn't feel or sound lean under load.
you don't need a high flow PV and switching to one wont change a damn thing, what needs to be adjusted is your PVCR's (power valve channel restrictors), on a stock metering block they're just a drilled orifice, on a HP metering block they are tapped and threaded for brass inserts that can be drilled and adjusted the same as jets or air bleeds.
how you can tell if you need one is that you should have about a 15:1 AFR when cruising, and when under high load about a 12:1 AFR. your jets will dictate your cruise AFR and your PVCRs will kick in to add the additional fuel needed for high load. Of course air bleeds and transition metering and even the idle circuit also all factor in- which is why you pay a good carb guy the money for making it all work together correctly.