283 cranks cast or forged?

[Boyan B.]

Are all factory GM 283 cranks forged? If not, where was the change to cast?

Boyan

[John H.]

Re: 283 cranks cast or forged?

Are all factory GM 283 cranks forged? If not, where was the change to cast?

Boyan

Boyan -

All 283's built prior to 1964 had forged cranks; Flint V-8 began producing 283's with cast nodular iron cranks in 1964, and Tonawanda started in 1965.

[Boyan B.]

Re: 283 cranks cast or forged?

Perfect, thanks.

[David L.]

Re: 283 cranks cast or forged?

Is there a way to tell when a 283 cranks was made? How do you tell if it is cast or forged? I have one that is cast "3735236" and "GM 74". I can not remember where I got it.

[Jim T.]

Re: 283 cranks cast or forged?

It has been a very long time, however I believe there is a difference that can be seen on the rear flange of the crankshafts. I cannot remember what the exact difference is at the moment.

[John H.]

Re: 283 cranks cast or forged?

Is there a way to tell when a 283 cranks was made? How do you tell if it is cast or forged? I have one that is cast "3735236" and "GM 74". I can not remember where I got it.

Dave -

The 5236 is a forged crank. If you look at the parting line on the cheeks of a rod throw, that will tell you if it's a casting or a forging. Cast cranks have a very narrow parting line (where the cope and drag sections of the sand mold met), usually 1/16"-1/8", and forged cranks have a much wider parting line (like 1/4"-1/2"), with tool marks perpendicular to the line, formed by the final trim die in the forging operation that sheared off the excess steel that extruded between the upper and lower halves of the forging dies. Photos below.

[Bruce B.]

Re: 283 cranks cast or forged?

John,
Thanks for the continuing education.
Bruce B

[David L.]

Re: 283 cranks cast or forged?

Dave -

The 5236 is a forged crank. If you look at the parting line on the cheeks of a rod throw, that will tell you if it's a casting or a forging. Cast cranks have a very narrow parting line (where the cope and drag sections of the sand mold met), usually 1/16"-1/8", and forged cranks have a much wider parting line (like 1/4"-1/2"), with tool marks perpendicular to the line, formed by the final trim die in the forging operation that sheared off the excess steel that extruded between the upper and lower halves of the forging dies. Photos below.

John,

My 3735236 crankshaft is forged as it has the wide parting line. Besides the "3735236" and "GM 74" castings there is also a "74" casting in another location along with a "B", "??", and "9" stamping. Could this be a date code (February ??, 1959)? I have owned the crankshaft since the summer of 1965 (right after I graduated from high school) when I bought a dis-assembled Chevrolet 283 engine. The only parts that I still have from this engine are the pistons ("3734627" casting), the rods (casting numbers "665", "651", "669", "639", "666", "657", "666", and "635") and this crankshaft. There is a pilot bearing in the crankshaft for manual transmissions. According to my 1963 Chevrolet Parts Catalog (Oct. 62) GM # 3815827 (forged 3835236) in Gr. 0.646 was the crankshaft used on 1957-1961 PASS., Corvette (8 cyl.)(exc. A.T., 348, 409, F.I. w/H.L. Cam).

Dave

[Terry M.]

Re: 283 cranks cast or forged?

Is there a way to tell when a 283 cranks was made? How do you tell if it is cast or forged? I have one that is cast "3735236" and "GM 74". I can not remember where I got it.

I believe a sound forging will ring when struck with a small hammer. A casting makes a dull thud. A cracked forging makes a dull sound as well.

[John H.]

Re: 283 cranks cast or forged?

John,

Besides the "3735236" and "GM 74" castings there is also a "74" casting in another location along with a "B", "??", and "9" stamping. Could this be a date code (February ??, 1959)? Dave

Dave -

The 5236 crank had a relatively long production run, from 1955-1963; yours is probably from 1959. Numbers are usually quite difficult to see on forgings. I expect the "74" is the forging die set identifier (like the pattern numbers on castings) - forging dies took a hell of a beating hammering cherry-red billets all day long, and there were multiple sets for each crank configuration.

Chevrolet-Detroit Forge was a pretty medieval place to work (especially in the summer).

[Mike M.]

Re: 283 cranks cast or forged?

Dave -

The 5236 crank had a relatively long production run, from 1955-1963; yours is probably from 1959. Numbers are usually quite difficult to see on forgings. I expect the "74" is the forging die set identifier (like the pattern numbers on castings) - forging dies took a hell of a beating hammering cherry-red billets all day long, and there were multiple sets for each crank configuration.

Chevrolet-Detroit Forge was a pretty medieval place to work (especially in the summer).

sounds like "The Threshold of Hell" john. regards,mike

[Terry M.]

Re: 283 cranks cast or forged?

Dave -

The 5236 crank had a relatively long production run, from 1955-1963; yours is probably from 1959. Numbers are usually quite difficult to see on forgings. I expect the "74" is the forging die set identifier (like the pattern numbers on castings) - forging dies took a hell of a beating hammering cherry-red billets all day long, and there were multiple sets for each crank configuration.

Chevrolet-Detroit Forge was a pretty medieval place to work (especially in the summer).

Back when I worked in a metallurgy lab I had occasion to visit several forge shops (and a few foundries). They were all like the "gates of hell," and one step removed (a tiny step at that) from "ye olde bloacksmithee shop." The working conditions were brutal.

The only thing worse were the steel making shops. Have you ever been near coke ovens? No not that kind of coke -- I refer to the kind used in steel making. Coke ovens ARE hell.