I just put a new starter in my 454 which started fine 3x, now for some reason it just "whirs"--basically sounding like the selanoid isn't pushing the starter out, but that the starter is turning without engaging the fly wheel (it's a manual). I have a painless wiring harness in the car which as worked flawlessly, and all the connections seem in tact. What gives?

I have a brand new starter that worked great the first 3 starts, now on the 4th, it simply "whirs" like the selaniod is not engaging and pushing the starter to the flywheel. It's new, stock rebuild. Chevy 454 in my 70 elco. I have a painless wiring harness that has been working great, and the connections seem to be fine. What's up?

Sounds like you described it pretty well, but the solenoid only throws the drive out part of the way. Then on the Bendix or starter drive, there's sort of a spiral thread that the spinning of the motor engages. The spinning starter motor then catches the thread and throws the gear all the way out to the flywheel/flexplate. At least that's how I remember them working...

Seems like something's binding, or the sol isn't throwing things out quite far enough.

Take it back if you can since its a pain to put it back in repeatedly only to find it still doesn't work and tests fine on the ground.

If you can't take it back, try loosening things and retightening after aligning the nose and rear cover.

Might also check for burrs on the spiral thread like part.

Sounds like a bad starter drive.

Return the starter for another one. Either a weak solenoid or a binding / defective starter drive.