Tuning help/suggestions

[Matt@RFR]

Power valves open when manifold vacuum drops below their rating. So a 3.5 will open (and dump fuel) when manifold vacuum drops below 3.5".



You size power valves two full numbers under what vacuum you have at idle. That way, it's far enough away so that any dips in vacuum won't tickle the power valve, and it also gives the idle circuit a chance to do it's job without dumping extra fuel the instant you touch the throttle.

(you have) 6" - 2 = 4 (round off to 3.5)