VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc Modern methods

I have noticed that the Engineering data for the 216 describes the rod bearings as "centrifugal babbit " referring to manufacturing process. I would doubt that anybody today has a process like that and I wonder what the differences are in the finished product.

The centrifugal babbit was spun into the rods.Before 1932 it was poured into the rod. It made the use of thinner babbit possible.This is one of the reasons that I always used Genuine Chev. rods for replacement.
I think with modern materials a good bearing rebabbiting place could equal the quality of the original.New genuine rods have become impossible to find.(actually the new Chev. rods were rebabbited but to original specs.)

Gene, do you know anyone that will do babbiting on rods sent in with the journal measurements from your crank or if there REPOs available in standard or undersize increments, without having to send the rods and the crank?

All they would need is the demension of a standard size crank. Fitting to your crankshaft is done by removing shims.If the crank has been turned to an undersize they would need to know what the undersize is and they would finish with thicker babbit to downsize the bearing.Then final adjusting would be done the way.Thats one advantage of the good old babbited rods.....Of coarse if you don't know if the crank is standard or not then you will need measurements.

I think that I read somewhere that the babbiting was as thin as .010. Is that a reasonable number or is it my memory that is thin ?

There is another option. Since the cranks in the old sixes and fours are steel and not cast iron they can be welded and cut back to standard. Some engine shops have a wire welder on the crank machine that will build up the throws. The crank is then straightened and then cut to standard. I have had two done in the past. Works out well. With standard crank standard rebabbited rods and mains can be used.

The babbit thickness was decreased over the years.IN 1933 it went down to .024" from .047".In '37 it made another jump and the 1948 and up is under .010".I have the exact figures but not handy.This was a great improvement in helping the bearings to stay tight............Crankshafts can also be hard chrome plated to be brought back to standard size.I had that done years ago for my "34 engine.

What other kind of cranks were there but cast ?

Forged.......Chevrolet was the only low priced car that had a forged crank.I believe it was in 1960 that the 2 bbl. carb. 283 was down graded to a cast crank.Also the later newer 7 main bearing 6's used a cast crank.The forging was harder but the cast iron was more porus and held the oil better (it was said)

Chip, did Oldchevyman contact you about getting rods and mains done on his car? He was looking for someone to redo his, he spun a center main up at Dennison.

The first cast crank was late 65 283's. In 62 they were all forged.
John

Hey John, Thanks for the Information on the crank. Also John I sent you a private message. Thanks :) :) :) :)