650 Mighty demon question


New Member
Mar 2, 2007
Its going to be here on Wednesday so i would like some advice before i put it on.
My combo:

DSS 306
9.5 compression
victor jr. intake
fully polished non-emission AFR 185's
1 5/8 long tubes.
Mac 2 1/2 full exhaust
Z-303 camshaft
1.6 roller rockers
3:55 gears at the moment. Might swap rearends to make it 4:30s
T-5 tranny

The car pulls 10 lbs of vacuum at idle
Around 37 degrees timing full advanced

I have read in several post that:
"that going from a 70/78 (out of the box jets) to 76/83 responds extremely well on the 650 Demons."
With 10 lbs of vacuum what power valve would be correct?
I have read subtract 2 from your idle vacuum and i have read divide by two for the correct power valve.

All advice welcome!!!!!!
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My advice: Don't touch a dang thing before you put it on!!

Put the carb on, run it, check the spark plugs to hopefully see a nice tan tint, and adjust accordingly. You are only making more work for yourself unless you know someone that has the exact same combo and already went through this process. And if that was the case, you wouldn't be asking us here.