Moparts

Help needed to identify a crankshaft

Posted By: vinnyd76

Help needed to identify a crankshaft - 10/23/21 11:47 AM

Looking for some help identifying a crankshaft. I'm pretty sure this is a Mopar big block forged crankshaft? However, I would like to know if there are some dimensions that I can quickly take with calipers to understand the current specs? Is there a spec sheet out there that helps enthusiasts?

Attached picture Big Block Crankshaft.PNG
Posted By: A727Tflite

Re: Help needed to identify a crankshaft - 10/23/21 01:08 PM

All production rod journals for B/RB are around 2.375”. Mains for a RB are around 2.750”. For a B, 2.625”.

Both use 6 bolt flex plates. Hemi uses 8 bolt flex plate, same dimensions as the RB.
Posted By: vinnyd76

Re: Help needed to identify a crankshaft - 10/23/21 03:06 PM

Originally Posted by Transman
All production rod journals for B/RB are around 2.375”. Mains for a RB are around 2.750”. For a B, 2.625”.

Both use 6 bolt flex plates. Hemi uses 8 bolt flex plate, same dimensions as the RB.




Thank you for the helpful info!
Posted By: dragon slayer

Re: Help needed to identify a crankshaft - 10/23/21 03:30 PM

Stock stroke is 3.75. You can estimate the stroke also.
Posted By: jughed

Re: Help needed to identify a crankshaft - 10/28/21 11:42 AM

I once asked if there were any way to tell by eye whether a crank is B or RB.

Dr Diff's reply.

"""If the rear main bearing journal is almost the same diameter as the rear main seal journal, you have an RB crank.

If the main bearing journal is noticeably smaller, you have a B crank."""


obviously need tools for accurate measuring, but that info came in handy when sorting through parts
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