Update #2.
So we opened it up and found the rear main bearing wasted. So, got online and ordered another set of .020 under mains. Looked at all of the others and they are perfect. The good news is the crank isn't scored and just had a bit of bearing material stuck to it which polished of easily.
Flash back for more history on this motor.
The owner (my buddy) took this car out and ran it down the interstate at 70 mph, which might have been OK had it had time to get broken in properly however, the motor only had 4 miles on it when he took this joyride! Overheated badly and took out the bearings and original crank.
For the second rebuild we bought a re-ground crank, reconditioned rods and all the other new bits necessary to get it back together. Now is where the seal problems seemed to really start to occur. After about 600 miles it started to leak, badly. Pulled the pan and found the rear main bearing was warn enough to warrant replacement, but is was worn more on the rear (toward flywheel) than front and the crank was undamaged. Back together with a new bearing and new seal. 350 miles and we are back to it again.
Each time the pan was off we checked the thrust with the dial indicator, checked the crank diameter, and plasti-gaged the rear main. Always checks fine although the rear of the bearing does seem very slightly tighter than the front edge.
This engine did not use shims and I believe left the factory with the neoprene seal as it came out of a 59 Biscayne.
Back to the present.
Tomorrow I plan to get out the dial indicator and micrometer and once again check all the clearances I can while we wait for the new bearings. I plan on checking with the dial the roundness of the rear main of the crank this time also as well as trying to check more accurately to see if it might have been ground tapered.
I am truly at my whits end with this haunted machine.
Question: Could the trans be causing a problem? 1952 cast iron power glide. Does the torque converter have to be indexed a certain way for balance on these engines?
I feel like maybe I'm missing something but I just can't figure out what. I runs soo good. Powerful, smooth, responsive, sounds great with the split exhaust, good oil pressure and decent mileage. Just can't seem to fix the rear bearing/seal problem.
I don't know if the bearing goes and take the seal out, or if the seal goes and then the bearing.
Sorry for the looong post, I just don't know where else to turn.
Chuck
