Is this a cast or forged crank?

[Moparfiend]

From my 1970 318 original motor in the sport satellite. Looks forged to me but I am no expert.

Is the 318 crank the same as the 340? Same stroke?

Thanks,
Ron

 

[WileE]

 

[pnora]

From my 1970 318 original motor in the sport satellite. Looks forged to me but I am no expert.

Is the 318 crank the same as the 340? Same stroke?

Thanks,
Ron

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Forged. Both 318 and 340 have a 3.3125 stroke.

 

[Moparfiend]

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Soooo what do you think?

 

[F4R/T]

Looks forged ,but I’ll admit your pictures don’t help.

 

[Cranky]

Soooo what do you think?

Look at post #2 again....

 

[Moparfiend]

I

Look at post #2 again....

did what am I missing?

 

[Moparfiend]

Looks forged ,but I’ll admit your pictures don’t help.

Does this help?

 

[Cranky]

I

did what am I missing?

Look at the very narrow parting line vs the wide parting line. A cast crank is molten metal that is 'poured' into a casting and a forged crank is 'pounded' into a shape. You can also find this process in a YouTube vid on how a forging vs a casting is made. It's well worth looking at!!! I was fortunate to see the process at an early age in real life. It's great to see it in person but seeing it in a vid is good too.

 

[69 Sleeper Bee]

Looks forged to me although 1970 318 cranks were cast.
Found this for what it's worth...
forged crank 318

 

[pnora]

Looks forged to me although 1970 318 cranks were cast.
Found this for what it's worth...
forged crank 318

I think there is some errors on that MP chart. Looking at the 70,71,72 parts book the 318 and 340 took the same internal balancer. Also only 1 crank listed for the 318. In late 72 there is a bulletin on the 340 showing the cast crank and the other external balance components.

 

[PROSTOCKTOM]

It's a forged crank. Just because it's 1970 318 means nothing in 55 years. Anything is possible over that time period.

The factory could have used what they had available on that given day, or someone could have added it years ago. How it really got there is irrelevant.

Put some good aftermarket connecting rods and pistons on and let it eat.

Tom

 

[Cranky]

Does this help?

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These pics shows a forged crank....

 

[Rebelrouser]

looks to be a forged crank the one picture shows a wide parting line. If you take the engine apart stand the crank upright and tap with a hammer, if it is forged it will ring like a bell, if it is cast it will just clunk.