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How far can you safely regrind crank journals

  • Thread starter Thread starter 1BadBird
  • Start date Start date
1

1BadBird

Question regarding building a streetable 455 Pontiac. Looking at building a 455 with approximately 500hp and wondering if its safe to use a crank that has been ground .020 on the mains and .030 on the rods.

The crank I have has been turned before and to do it again will leave it with the sizes noted above. Wondering if I should have any concerns about longevity or 'bearing speeds' with the smaller journals.

Any input would be much appreciated
 
i thought one of the fixes was to weld metal back onto the journal and then machining. You may want to contact a crankshaft only type of business for advise.
 
melsg5 said:
i thought one of the fixes was to weld metal back onto the journal and then machining. You may want to contact a crankshaft only type of business for advise.
Click to expand...

Mels right. You need more metal not less. the problem with what you want to do is exactly the goal which you are trying to accomplish. When you grind them down you are weakening them and reducing their lifespan.

Contact someone who does this type of thing as a profession and see what they would recommend to do.
 
journal sizes

I understand the need for more metal in an ideal situation but when the crank has gotten worn as it has then would it be acceptable to run a reground crank in a 500hp engine?

I would think that having the journals built back up and then turned to stock sizes could become cost prohibitive in which case a person might be better off to simply buy a new one. Expense is what I'm trying to avoid but also didn't want to invest any $$ into something thats not going to be capable of supporting 500hp.

So I guess the question is whether a crank turned to the sizes originally noted would be able to handle the horsepower? :confused:

Thanks for the feedback :)
______________________________
 
With kind of power I would buy a new crank. A crank that has been turned that much will not hold up to that kind of power if you get on it. I would hate to see spend all that money and end up braking the crank.
 
speak to a shop that specializes in doing crank shaft work, not an ordinary machine shop, one that does race type machine work on cranks
 
I have run cranks at .020/.020 at that kind of HP but no further with any HP gain it's better to have more surface area to dissapate both heat and rotational forces.
but as said contact a shop that specializes in machine work to see what they say
the good thing about most Pontiac crank sizes are they are larger than most at the start (compared to like a Small Block Chevy crank)..
 
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