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Author Topic:   GM Steel Cranks.....
Drogo99
Member
posted July 16, 2004 02:24 PM
they are crack prone but at 6200rpm you will be fine.

luke

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UNVRNO
Member
posted July 16, 2004 04:53 PM
This is good to know. Just spent 650.00 on a new gm steel crank and it is no good???


Racer X
Member
posted July 16, 2004 05:04 PM
Its also possible to feel the cast crank vibrate when it cracks before it really comes apart. With a steel crank, it just comes apart.


quietmans
Member
posted July 17, 2004 04:55 AM
The motor I am building now will have a gm steel crank and gm pink rods,not sure on what piston yet? Will be .060 over flat top 4 valve relief, what is good in this line?


stockcar5
Member
posted July 18, 2004 09:15 PM
quiet....the stock steel cranks are the ones people dont like. im assuming if you spent 650$ on a new one that it is a gm performance parts crank? if so thats a different story.

luke

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B36
Member
posted July 18, 2004 09:23 PM
:Yes it is original gm forged steel crank,the bottom end is the last place I want to explode.


3dirtLm
Member
posted July 19, 2004 09:13 PM
Already have a set of pink rods but we have agreed they are not what we will use. The crower seems like a real good choice,but why not .060 bore?


Raz_900
Member
posted July 20, 2004 07:49 AM
quote:
Originally posted by quietmans:
Already have a set of pink rods but we have agreed they are not what we will use. The crower seems like a real good choice,but why not .060 bore?

.060" is not advised with a '80-newer block for racing purposes. On a pre '79 block, it's a very good idea to have the block sonic checked to verify wall thickness. It's not uncommon to have a bore or 3 shift making the walls thinner in some spots. For mild street use, you can get away with .060" on the older blocks most of the time.

Also, why pay all that money machining a block that can only be used once? Or twice, one tear down for a re-ringing then it's done. If you start at .030", then you have a rering, then .040", rering again, maybe .060" and rering again. Much more use out of a block that way. I've even seen .035" pistons from somewhere (JE or Manley I think??) to add more life to it. If you're not worried about that last 2-4 HP, start at .020" if the block will clean up.

I'd rather find a good block and use it 5-10 times than have to find 5 blocks and use them each once or twice.


leftturn73
Member
posted July 20, 2004 12:12 PM
I've run the GM cast and steel crank in many different combinations over the years. My 2cents is this: do the work up front check for cracks and have it balanced. (A good balance not just weight matching). Use your head don't put a cast -.020 turned crank in a 600HP engine, use it in somthing smaller. I have used a cast crank standard and -.010 under in a 450-475HP motor for up to two seasons then time to replace. I would not hezitate to run a good steel crank standart or -.010 in the 500-600HP motors just have checked on rebuilds. *Try to run light pistons and have your rods checked for sizing and my opionion your motors will hold up.


UNVRNO
Member
posted July 20, 2004 08:02 PM
Guess I was not looking at the long run but that does make more sense and the couple of lost horses will not matter that much.Thanks for all the input has been a great help in deciding on what I will do.


Okie11m
Member
posted July 27, 2004 11:20 AM
I've got a 12-1 motor that has seen 7000 for two years in a Street Stock class with a .010 under forged GM crank out of a truck. It is ballanced.


Xtrem4U
Member
posted July 28, 2004 07:09 AM
Amarillo, 200 bucks.


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