help

[azn750]

i have a 1979 Chevy Malibu.

When i first bought the car, there was a hesitation problem...i thought it would be related to the fuel so i replaced the filter, rebuilt the carbeurator, replaced the fuel lines and the fuel pump. After replacing all of this i still had hesitation...so i thought maybe i had to readjust the carburator (vacuum advance) i did this three times. After doing all this i still had a problem so i replaced the plugs, wires, cap, rotor and distributer, and rebuilt the heads and put on new rocker arms, studs and keepers. Two grand later i still have a hesitation problem. anyone got any ideas?????

[jveik]

make sure the accellerator pump is putting the right amount of fuel shot into the motor when you hit the gas... did you look into if the cam might be bad or maybe the timing chain is just a little old and has some slack in it? i would replace the cam anyways if i already spent 2 grand to replace everything else. just make sure to not spend money you dont need to. my old 350 that was in my truck would hesitate really bad when you hit the gas at a stop, like it would die but then kick in and take off. over time it got worse and worse until it got so bad that it would just backfire through the carb whenever i gave it more than half throttle until i was going at least 80 or so. i definately think the cam had something to do with it, though i havent pulled it out yet to see...

[mechhound]

Are you using the 10% ethanol? This usually caused hesitation in my old Fords. I see you live in Wisconsin, I suspect they have a law mandating 10% ethanol. I know Minnesota does. If possible run pure gasoline, if you aren't already. Also advance the timing as much as possible without causing ping, if you haven't played with that idea already. Hope this helps some.

[rhandwor]

Spray some carburetor cleaner around the intake manifold if you have a vacuum leak the engine will smooth out. Also plug the vacuum to the vacuum booster and see if this helps. Check the vacuum advance for the timing. Also check the timing with vacuum advance plugged.
Did you replace the timing chain when you did the heads?

[silicon212]

Cam/lifters/timing chain. Replace all of the above - you have a valvetrain problem.