I just put a new 750 Holley Double pumper on my car and replaced the 650. I used the 4.5 power valve from the 650 and now the engine seems to surge while cruising and pops just off idle if i goose it. I did a vacumm test at idle in gear and only get around 6 inches of vacumm. I get 9 inches in park. Where do i start to begin, could it just be a vacumm leak somewhere. The car ran fine before I put the 4.5 power valve in the carb, I just put it in there because I was told to start with what I had before in the 650 carb. I turn the idle screws all the way and vacumm actually goes up and the engine doesn't stall like it is suppossed too. Thanks, Erik
68 Camaro RS, Built 355, 274 Comp Cam, Sportsman II Heads 200 c.c. 2.02. Ported to Performer RPM Manifold and 1.75" Headers, 1.5 Roller Rockers, 650 Holley, Steel Crank, 4.11 Gears but no posi yet! TH350 tranny w/ shift kit.