Loss of RPM on takeoff run.

[jasoneh]

What would cause a loss of RPM during the take off run before lift off? The throttle was pushed in slowly and generated full power for about 1,000'. Then the RPM starting dropping. I let it drop about 400 RPM, before I just pulled it back to idle. I taxied back and tried it again with the same result. The engine is Continental C-85, converted from a C-75.

[BeeMan]

One possibility is inadequate fuel flow; clean all screens and check sustained fuel flow.