VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc main bearing measurements

I have my 1932 194 cu in at the machine shop. The crank will need to be ground. The only reference I have for the original size of the bearings is in the manual I left at the machine shop, and it measures the bearings in increments of fractions of an inch rather than thousands of inch. As I will need to order bearings (anticipate .020 under), and the crankshaft will need grinding, what size, in thousands, was the original crank bearings? I understand all three are different. Block casting number 836573.

The bearings will need to be poured and then sized to match the crank. Or the crank can be welded and machined back to standard. Or you can have the '32 rods machined to accept inserts.

Have the machine shop grind the shaft, polish and then tell you the undersize. Then with the actual measurements send the rods and main shells to an expert in repouring. The main bearings are not "precision" types. So the mains will be sent back semi and will need to be line bored to fit the crank. The rods should be repoured sized with 0.008" shims installed in each side. Shims should also be used between the main caps and block when line boring.

And, if the machine shop doesn't know what old Chipper Dipper is talking about.......then get your engine outta there.......fast!!!!

I don't understand. The mains have replaceable inserts, so why repour? The machine shop does have experience with these engines, and he has asked if I could find the original size of the crank for the three bearings. What am I missing?

The bearing are inserts -but- when new the inserts had a rather thick amount of babbit on them.The inserts were in stalled in the block, main bearing caps tightened,The a boring tool was inserted thru the bearings.This would size the bearings to the correct size and also the three bearing "holes" would be correct aligned with each other.Example-one not .011" higher than the rest.

This was necessary if the inserts were replaced on Chevrolet engines up thru 1947.In 1948 they began using precision type inserts in the new cars.These were made in a uniform size, had a thinner babbit, and did not require line-boring.

After 1948 Chevrolet made the precision type inserts for engines back to 1929 so the boring process was not necessary.As these precision type inserts would be next to impossible to find for a 1932 today it will be necessary to have the present inserts rebabbited and line-bored as was done originally.The complete process is shown in my 1934 shop manual - I would assume it will be in the 1932 manual also.

As mentioned, if the shop does not understand the operation they are not experianced with this old process and should not attempt the job.

This was the common method on most cars until the '30's.

Prior to inserts the babbit was poured directly to the block and caps.Even the F**d V-8 had the babbit poured directly to the block up thru mid 1936.

Chev Nut is totally correct. It sounds like the shop that has your engine does not have the experience when it comes to rebuilding old Chevrolet poured babbit engines. To avoid a lot of expense and grief later, you should get your engine back from them and send it to professionals who know how to work on and line bore the old Chevy engines.