Ignition Issue

[lmracer36b]

We are having an issue in our crate late model that we can not diagnose. When the car revs up steadily in the pits, it will hit about 4200-4400 rpm and then misfires/bogs down until you give enough gas that it jumps to 6000rpm and then works fine. Out on the track, it will stay between 3800rpm-4400rpm and will never reach the 6000rpm because of the extra load from the drive line. Just for some background info we have just had the engine in for a cleaning and a tune because we thought the engine was the issue but once we got it back, we still have the issue. We also changed the cap and rotor on the distributor and that was also adjusted by the engine builder. We also tried some one else's coil pack but that did not solve the issue. Also the fuel pressure is good so we do not believe it is a fuel pump issue. Any help with this would be greatly appreciated as we are out of ideas.

[CCHIEF]

Look into pickup up polarity if you have a MSD box. What distributor are you using? Is the advance locked out. How old are the plug wires?

[LIS20]

We had a similar problem and completely rewired the ignition system - turned out it was the carb - the primary float for some reason was flooding out the engine causing it to pop and crack coming out of the turn to about the flagstand and then it would clear out.