First plug change.

SuperStock426 said

That 8.5 power valve is a bit high I would think. I would think you'd need one 3.5-4.5. How much vacuum is your engine producing? I'd recommend the AR3911 Autolite spark plugs depending on which cylinder heads you're using.

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Well, I'm a firm believer in running the PV closer to cruise vacuum. I average 13-17" vacuum with max up to 20" at cruise depending on speed and the only reason I pulled the 10.5 PV out was it came in a hair too soon when stabbing the gas at 30-ish mph. But, with things down low still a bit outta whack, once I get the transition area dialed it may go back in because I suspect I wasn't completely on the boosters yet. I like to get a leaner PMJ setting and have the PV enrich at the instant I get on the gas from the main-circuit cruise. I realize everyone has different ways of getting the job done though, and I do appreciate your input! Thanks.
I currently have Edlbrock RPM heads, they recommend starting with RC12YC champs. With the same heads and a little less SCR on my 440s I used to run autolite 3924 before switching to the NGK 5, and they worked good.
I love this stuff!