[Michael C Henry]

Quick Fuel Techknology said that I want to check the vacum at idel in gear.and go 1.5 below that. As I understand it when you open the throttle you get the initial squirt of gas from the accelerater pump and the vacum drops, the power valve opens and delivers anm additional supply of gas ( in addition to the fuel being delivered through the boosters via metered jets) untill the engine catches up and is running closer to effeicient.the vacum builds and power valve closes and the engine continues to run on the fuel controlled by the jets alone.
I missunderstood and bought a pair of 8.5s a while back.When I had all the gas running in because of the plugged air bleeds and all the backfiring .I changed the powervalves It wasn't drulling but it started backfiring more and got worse as it went untill I quit.Plugs were all black.I'm starting with the 3.5 this time.The lower I go the sooner the valves close.Too early and I loose power.I have to get it running to get a reading and start to tune .