Have a hard time getting Holley 390 setup. 77 Chevy 250 clifford cam, headers, clifford intake, and clifford valves and head specs. Started jetting with clifford recommendation and could not get rid of lean spot each time u shift let off gas and stab throttle u get a hesitation. So I took to get dyne tune and developed and intake gasket leak when I got there and they three it on dyne and said it was way to lean and went up in main jet 9 sizes to 60 main 6.5 power valve and I have 17 to 18 lbs of vacuum. the pump nozzle is a 31 and pink cam. I don't have a hesitation but all my get up and go is gone very lazy power band. Need to know where to start and where are your hoped up 250s running with holley 390?
