Forged crankshafts

[Gary runner]

How can you tell if a forged crankshaft is a 383 crank or a 440 crank. The only thing I can find is the main bearing journals dia. measurement from the service manual. Is there any other way. Thanks.

 

[RemCharger]

You could weigh em

 

[toolmanmike]

Look at the parting line. A small sharp line is a cast crank and a wide hammered line is a forged. You can tell by the shape of the counterweights as well. Sharper and more blocky, cast. Contoured and more rounded, forged. The forged cranks also sound line a bell when you tap the weights with a small hammer. Quite a clear distinctive ring to them.

 

[zyzzyx]

You figured it out with the main bearing diameter!

 

[RemCharger]

Look at the parting line. A small sharp line is a cast crank and a wide hammered line is a forged. You can tell by the shape of the counterweights as well. Sharper and more blocky, cast. Contoured and more rounded, forged. The forged cranks also sound line a bell when you tap the weights with a small hammer. Quite a clear distinctive ring to them.

View attachment 1315836

Cast cranks weren't the topic!

 

[33 IMP]

my guess is he hasn't got a way to measure the mains. My suggestion would be: get a $10 digital caliper from harbor freight.
Can't be a car guy without tools.

 

[Lefty71]

How can you tell if a forged crankshaft is a 383 crank or a 440 crank.

Well, a factory 440 crank stock stroke is 4 tenths of an inch longer than a factory stock stroke 383 crank, in very, very round numbers. If you are saying you dont have machinist tools to measure.... your options are take it to someone who can, or possibly you could make up a rudimentary jig out of wood, hell even popsicle sticks to measure one crank, then see if it compares to the other.... you can compare the mains too with a set of dividers or popsicle stick and glue that too.....

I heard a story once of some freshly imported Polish I think plumber/fitters way back in the day... they had no tape measures and needed iron pipe threaded by the local hardware/tool shop.... they came in with strings cut to length of the pipes they needed cut and threaded. No joke to be had there, they were getting paid!! I bet they can afford proper tools now!!

Good luck with your project, Lefty71

 

[toolmanmike]

Cast cranks weren't the topic!

True that. I didn't read the post well enough.

 

[Gary runner]

Thanks for the information. I have been a car buy most of my life. Yes I have a mic to measure the journals. If the journals have been cut down at some point, you may get a diff. reading. The cranks I will be checking are at a friends house and I wanted this information before I go there.

 

[Lefty71]

Mains certainly can be cut down to fit a 440 crank in a "B" block....
Also, if the rod journals have been offset ground to make a stroker crank, you`ll likely be able to see that has happened with the naked eye. Let us know what you find...

 

[Diodedog]

You could weigh em

Years ago I weighed 4 cranks, a cast 440, a cast 400 a steel 383 and a steel 413, all weighed the same.

 

[RemCharger]

Years ago I weighed 4 cranks, a cast 440, a cast 400 a steel 383 and a steel 413, all weighed the same.

That's interesting, I wonder what the superstock specialists think?
@GTX JOHN

 

[33 IMP]

Okay, sounds like you might be expecting to find a 440 crank cut down to 383 mains, and looking for another way to i.d. Other than stick it in a block, I think a good visual inspection around the #3 main might give a clue if it has been cut down a bunch.
Offset ground rod journals for a stroker, are easily id'ed too, they will be way under stock dimensions, usually 2.200 for a bbc rod.

 

[GTX JOHN]

You can buy a set of calipers at Harbor Freight for $20. sometimes
The are pretty much Vital in this Hobby!