turning BBC cranks - Team Camaro Tech
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post #1 of 5 (permalink) Old Mar 20th, 08, 02:04 PM Thread Starter
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turning BBC cranks

How far can I safely turn a BBC crank, specifically a 427. They make bearings for .040 and .050 undersize for the rods, but can the crank handle that much of a cut wthout sacrificing too much strength? Thanks.
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post #2 of 5 (permalink) Old Mar 20th, 08, 03:40 PM
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Re: turning BBC cranks

If I had to turn a crank more that .20 I would start looking for another crank.

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post #3 of 5 (permalink) Old Mar 20th, 08, 05:57 PM
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Re: turning BBC cranks

The crank will handle any size that you can get bearings for. It is very common to offset grind the rods down to Small block size, thats .100" smaller ! Small block 400 cranks are turned down to 350 size every day to make 383's. Thats a .200" grind !! Most crankshafts are so over engineered that it is not a problem anyway.

What is more important than the size is having the crankshaft properly reground, especially keeping the proper radius on the journal ends.

Bill Koustenis
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Waldorf Md
1971 Chevelle "Heavy Chevy" original owner

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post #4 of 5 (permalink) Old Mar 20th, 08, 06:25 PM
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Re: turning BBC cranks

I am almost positive you can buy .100" UNDERSIZE BB crank bearing sets, the suckers are THAT tough!!

And remember, the SB guys turn SB cranks down to Honda rod sizes that I want to say is 1.88" or so, but I may be off here!! I know they are SMALL dia.!!!!!!!

And they spin them upwards to 9,000 rpm!!


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post #5 of 5 (permalink) Old Mar 20th, 08, 06:49 PM
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Re: turning BBC cranks

Originally Posted by windycity1 View Post
If I had to turn a crank more that .20 I would start looking for another crank.
I think you meant .020".Typo??:BBC cranks have been ground to the honda 1.88 journal size.My machinist polished my old 427 crank that was ground .030/.030" with no concerns from him or myself.

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Last edited by fatblock; Mar 20th, 08 at 06:59 PM. Reason: add
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