First off let me state God was watching over me. Pulled the trans in my racecar for freshening. Started reinstalling the trans. Rotating the crank to install the 3rd converter bolt, crank stops, dead. Won't move either way more than 2-3 degrees. Don't want to force it backward with the Jessel belt. Pull the dist and oil drive, pump spins, losen the alternator (brand new) and vacuum pump belts, nope. Pull all the rockers and pushrods. All look great. Lifters can be pulled up with a piece of tig rod. Now the crank will rotate counter clockwise about 300 degrees and then, stops dead. Pull the trans back out to make sure something didn't hang up in the flexplate. I mean it was fine when the crank was rotated to pull the trans, right? Found nothing. Tried a bore camera saw nothing. Rreinstall the trans and pull the pan. Everything looks good. Pistons # 4 &# 7 won't clear TDC about 30 degrees either side. Take a guess at #4 1st. Pull the header. Pull the exh valve spring and replace with a checking spring. Try the camera and see nothing. I'm lost. Decide to pull the passenger head. Pull the intake. One last gasp. Pull the intake valve spring and swap with checking spring. Push the valve open. What do I see. A undamaged 5/16" nylock nut setting on the piston below the exhaust valve. Where did that come from? Only thing I can think of is when the accumulator was relocated during the alternator upgrade. It's the only item thats been removed that uses that nut. Engine had been started several times to check the alternator. Then moved into the hoist bay. Then started again after the oil change. I really hadn't cracked the throttle far until then. No marks on th episton. Cylinder leaks 5% cold. Not all a total loss of time. The screen windage tray was cracked again. So thats not going back. I'll fab a baffle above the pick up. The intake gaskets are climbing the head, again. So I'll replace them as well. First race is in 2 weeks.
Doug