How to tell forged cranks apart?

fastsc92

Registered User
I was able to obtain a spare motor last year from a high school engine program for free. I dont know what year the block was from, but it is super clean. I bet it only has 30k on it. Anyways, how can i tell if the crank is not from the early style. I have no idea what to look for when figuring out if its cast or forged. There are some stamped numbers on there if that helps.

Also, all the main caps were off. I know the location of the #4 cap, but the other three i dont know the order. I was thinking that those little arrows on the caps point toward the front of the motor. Also i was thinking that those arrows mean something. There is one with one arrow, two, and three. I'm guessing that one arrow is #1 main, and so forth. Am i correct here??
 
Too be honest I think they are all the same....

They just have different dates when they were made ... All cranks are shot peened before they are used this means that they hit them with a heavy hammer to ensure there are no cracks or hollow spots ....

Cranks are made by taking to seperate castings then joining them together On the SC i believe they are joined together at the 3rd and 4th rod journals...After the castings are joined then the crank is forged and ground to specs ...This is the way I precieve the process to be.....

I believe the whole durcast VS forged debate has been over complicated... There was a Crank supplier on the early SC these folks went by the name duracast.... When Duracast could not provide any more cranks ESSEX motor plant went ahead and cast cranks for the SC themselves...
 
shot peened before they are used this means that they hit them with a heavy hammer to ensure there are no cracks or hollow spots
Uh, no that's not what shot peening is... shot peening is when a metal piece is blasted with small metal shot, which causes compressed stress in the surface to help prevent cracking, and hardens the surface.
 
A forged crank will have a fairly distinct parting line from the forging process, while a cast crank will have a similiar parting line it normally is less sharp/distinct. My .02.
 
Also a forged piece will tend to ring while a casting will have a duller ring or thud. This is a byproduct of the forging process which tends to align the chrystalline structure of the metal.
 
VTBIRD said:
A forged crank will have a fairly distinct parting line from the forging process, while a cast crank will have a similiar parting line it normally is less sharp/distinct.
Actually a cast crank will have a sharp thin parting line whereas a forged crank will have a thick parting line (like 1/2" to 1" wide).

And yes, if it rings, that is another sign it is forged.
 
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