ok got a 470hp 383...howards roller cam, msd streetfire, air-gap..cars runs pretty dam good but started having a problem with it popping back thru the carb on a rev from idle..carb is a proform 750 dp..we put a 50 acc pump on it..no luck..jetted up too...my buddy is a really good carb guy and he's running out of tricks to try..sooooo we took a good known 850 put that on..same issue....the 750 under load pops at anything under 1800 the 850 pops under load at anything under 1600...i'm thinking this isnt a carb issue..timing is set 8 deg...this car runs hard all the way to 6k no problem...late last yr it did it to me once in the box and made for a bad burn out..it seems worse this yr..no other issues holds 17-22 in of vac. at idle..not sure where else to look..valves are adjusted correct....ignition???..plugs look good..ngk #7's..converter seems to stall about26-2800 on the foot brake..soooo what do you guys think this might be?..thanks for the help!
max
max