3732692 Crank grind

[3483x2]

I recently saw a video about doing crank grinds. Granted the subject in that video was a '70's crank.
The main take-away from that video was to be careful about removing the top surface material on cranks since removing that extra hardness benefits weakens the crank.

Anyway, this got me thinking about my 3732692 which I had ground 10/10 and it being a way older crank, whether I should concern myself about weakening it.
Lesson learned: Approach engine build tasks by taking away as least material as possible.

 

[La Hot Rods]

Ran a lot of .010 under cranks with no problems. One could send it off and have it surface harden again if they were concerned.

 

[William Malik]

Interesting thing about GM sending cranks out to be hardened. My uncle was a supervisor at the Flint assembly plant crankshaft Division since 1954 when it was opened until the mid 70's when he retired. He told me when they sent out the high performance cranks to be tufftrided is what he called it. Every one that came back had to be spun on a special machine to be straightened. About 70% where bent.

 

[Don Jacks]

10-10 IS nothing to worry about on your crank,Yes the big three put a hardening treatment on their hp cranks back in the
late 60's-early 70's.Yes it was only about .003-.004 thick.Only in max effort engines,such as Nascar was it any reason for concern,.

 

[427John]

That video is probably referring to the nitrided cranks used in some HP 427's and 454's such as L-88's and ZL-1's, not sure if the 425 horse engines used them too but it definitely wasn't used across the board on steel cranks. It was a surface treatment that only went in a little way, polishing them was usually OK but a grind undersize would usually eliminate it, while you lost the advantage of the hardened surface it didn't make the crank any less durable than the other normal forged cranks. It was a treatment that was developed for the diesel versions of the big GMC v-6's, the gas versions were fine with a regular forged crank but the diesels didn't hold up too well until they surface hardened the journals.