VCCA Home Forums TECHNICAL - 1945 AND NEWER 1955-1957 265 - 283 CRANKSHAFT QUESTION

Hi all. Can anybody tell me what years this crankshaft will fit. I know it will fit 1955 to 1957 cars 265 & 283. Forging # 3735236. It is not threaded for the balancer. I guess I would like to know when Chevy started threading the crank. Thanks....Jim

Jim,
That is a forged crank and will fit all small journal blocks. Can be used in any 265, 283 or 327 block. (You could build a small journal 302 with that in 327 block!) I am not aware of any small journal cranks that were drilled for a balancer bolt at the factory. The large journal arrived sometime late in the 1967 production run. I have found that these early cranks were not balanced all that well from the factory. The technology evolved over the years of production. The last 55 I did was few years ago for a member with a Vette. It needed a lot of "drill work" on the counterweights, same with another one I did
Hope this helps
John

Thank you John! I appreciate the info. Jim

I willl explain as best I can,
Will be using a 1959 parts book for reference.
There were actually three different part number crankshafts shown for 1957 and two of them use the 3735236 forging numbers.
One is part #3742332 and forg #3735236. its application is 1957-59 283 and 1957 265 cars (and small trucks) with standard transmission and thin head pistons.

Part #3752062 is forg #3735236 and listed for 57-59 283 with automatic trans (they would have thin head pistons)....pilot bear hole was larger for Turboglide so they just sold that ceankshaft for all automatic trans. evidently.
These ceankshafts were all balanced for the lighter thin head pistons.

Part #3742333, forg #3727449 is listed for 283 1957-59 with fuel injection and high lift cam (domed pistons and heavy duty trucks which had forged pistons.) Crank was blanced for the heavy pistons. This is necessary in a V8 because it does not have natural balance and the crank and pistons must be in balance with each other. As an example they made a balance kit (weights that bolted to the balancer) for when the domed pistons were installed in a non-dome engie, this was a common practice with rodders.

The bolted on balancer came along much later. The older ones were just a friction fit. The balancer on my stock 1957 283 tended to pull off. I got a bolt and larger washer that the later engines used, drilled and tapped a hole in the center of the crankshaft and bolted the balancer in place.Did this about 20 years ago and doing fine.The crank is not hardened in the center and drills quite easy.

Different year parts books may show different part numbers as they changed and up-dated numbers frequently.

Hope this helps a little. If you have a stcik just be sure to use the correct pilot bearing for the shaft you have.

Note that the 1957 265 used an under bores 283 block, 283 crankshaft and special heaiver piston pins to get the proper balance for the 283 shaft.

Note that the balance mentioned is not if all pistons were of equal weight, rather that the crank weights were in balance with the pistons. The 1955 V8 was balanced after assembly. The actually spun the engine and holes were drilled in the crankshaft weights to get the proper balance. Very advanced for its time.

I did forget the pilot bushing aspect, but small journal 3" stroke is a small journal 3" stroke.... and I presume everyone always balances an engine with new pistions. I had run into the turboglide crank problem once with 348 using a stick. There is a pilot bushing to make it work, and is a little tricky to find.

Gene's info is very useful if you are using all GM parts. However we do need to keep in mind the need for these different parts were for a warrenty swap on a new vehicle when the pistons and rods are not being disturbed. I am not looking at it from that perspective, and that I have a good forged crank that does not need a cut and I can get away with a polish and radius of the oil holes

I only had one balancer walk off that was after the main bearing spun on a 327 at about 7,000 RPM in a 63 Biscayne I had some time ago. If a balancer walks I think there is another major problem going on
The 3735236 casting has applications listed up through 1967
John