Power Valve Selection: The Definitive Answer

qkcuda said

I just installed the 10.5 power valve and dropped the primary jets from 72 to 70. Went out for a long drive and my lean stumble at part throttle is gone. My cruising A/F ratios are now in the high 13's, so heading in the right direction. My idle A/F ratios did not change at all, maybe a touch leaner if anything, so the fact that I have a 10.5 power valve and 8.5 inches of vacuum at idle is not a problem. I will be headed on a 1 1/2 hour trip to Moparfest in the next two weeks, so I will leave it like this for now and see if I want to drop the jetting again.

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Thanks for the update. Can you remind us what power valve you started with?

Glad it helped you out. Late opening power valve timing can put a big hole in the fuel curve and you almost can't tune it out with pump cams and squirters.


EDIT: if you are still rich at cruise, drop the main jets a bit more to clean up the cruise. Then, when testing for WOT, it may be lean. If that is the case, don't touch the main jets. You open up the power valve channel restricters to make up for the fuel at WOT. Once you get the hang of it, you'll be helping anyone who will listen. Most won't.