Thread: Small block chevy main bearing proplem (assembly)

Tweet

I am trying to put a small block chevy 350 back together and the rear main bearing seems to be wrong. It does not fit over the crank. The crank is ground .010 under and the bearings match in this respect. The thrust surfaces of the bearing do not fit into the crank. The old bearing and the new bearing have the same part number stamped in the back 32020-cp. The casting number on the crank is 932442. Measuring across the bearings there was about .020 difference between the old bearing and the new bearing, with the new bearing being the larger of the two, which I am sure is the problem. I took back the first set of bearings thinking it was a defect and the new bearings have the same problem. From what I can tell from the numbers I think this is a 1975 motor. Are there different types of bearings for this? The bearing brand I am using is Federal Mogul. If anyone has any suggestions I would love to hear them.

Thank you,

Josh

Assemble that journal without the crank - mic the bearing inside diameter.
Then mic the crank outside diameter and see what the difference is.

Josh, you appear to be saying that the bearing is too long and the bearing does not fit onto the crank....have you tried to put the bearing on the crank with the crank out of the engine? The length of the bearing (the thickness of the thrust surface) will be longer on a new bearing set since the thrust surface has not yet worn. Look at your thrust clearance spec....it is a fairly close fit....

Regarding the bearing brand...Federal is a good brand. There should be another number on the bearing; something like 010 for 0.010 under. You should always check the clearance on each bearing, even if it is with Plastigage. Also, check the thrust clearance with a feeler gauge.

You may have over size thrust bearing set.

Racecar, good call on the oversize thrust distance....probably what is wrong. Look up the FM
32020-cp and see the description

Originally Posted by robot

Josh, you appear to be saying that the bearing is too long and the bearing does not fit onto the crank....have you tried to put the bearing on the crank with the crank out of the engine? The length of the bearing (the thickness of the thrust surface) will be longer on a new bearing set since the thrust surface has not yet worn. Look at your thrust clearance spec....it is a fairly close fit....

Regarding the bearing brand...Federal is a good brand. There should be another number on the bearing; something like 010 for 0.010 under. You should always check the clearance on each bearing, even if it is with Plastigage. Also, check the thrust clearance with a feeler gauge.

The bearing did not fit on the crank. I am thinking that racecar is on the money. That was suggested on another board I go on, and the measurements check out with the story. I found a set of bearings today that were the .010 undersized that I need without the thrust bearing being larger. I should know in a little bit, I will let you know.

Josh

Everything went together perfectly with the new bearings with a standard thrust surface. Thank you for the help.