# Ram Air crankshaft ID question



## JoshE (Feb 28, 2021)

Hello All. Trying to ID a crankshaft and have a mix of cast and stamped numbers. This crank came out of an estate sale of a long time Pontiac enthusiast. There are cast numbers of 978 followed by stamped numbers of 4054. Underneath the stamped numbers it looks like the casting was ground down. Rod and main journals spec out to 350/400 sizes. This has ARMA STEEL cast in as well. 
For all my looking I do not see this casting number listed anywhere. There is a casting number 9794054 out there that is ARMA STEEL that is for a 1970 Ram Air. Anyone with thoughts out there on the ID of this crank or other details on the crank I can look at to help with positive identification?









Thanks All


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## O52 (Jan 27, 2019)

From my 68 MPC 

The number is 9794054 -
68 Firebird/Tempest with WU, WY, XT, and XW Ram Air II engines

Could also be for later year RA IVs


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## PontiacJim (Dec 29, 2012)

From memory, the Ram Air crank is the same as other cranks, but was ground a little undersize to provide more oil clearance - as they were designed to rev higher than other HP engines.


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## JoshE (Feb 28, 2021)

Was it common to have stampings like this alongside the cast numbers?I will take a closer look to see if undersize. This is a better pic:


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## PontiacJim (Dec 29, 2012)

JoshE said:


> Was it common to have stampings like this alongside the cast numbers?I will take a closer look to see if undersize. This is a better pic:
> View attachment 141021


Yes, Pontiac did do things like grind off the end of a casting number and then stamp numbers as seen. Heads for the RA engines have had the casting numbers ground off and stamped. Again, I believe, with out researching on our site, that the RA IV engine block was done the same way. So it was done as the factory used a "typical" production part, did whatever modification was needed for that engine type in question, and then might grind off part of the casting numbers and then stamp them. Seems this is a "theme" with the RA engines regarding certain parts that could have been used on any HP engine and modified for RA use.

This re-stamping can be an issue when trying to prove the part is authentic/original if it is not found on the original car that it was born with.


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## Gremlin66 (Oct 11, 2009)

I have a 1970 Ram Air block that has the last number ground off and a hand stamped “5” at the end if memory serves. Crank is original to the block but never looked at the casting numbers. I know it was Arma-steel from the machinist that did the work 25 years ago.


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## Gremlin66 (Oct 11, 2009)

Sorry forgot to mention it was Ram Air IV block/ crank


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