412 SBC crankshafts - Team Camaro Tech
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post #1 of 8 (permalink) Old Jan 25th, 09, 09:03 PM Thread Starter
SY1
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Dave
 
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Question 412 SBC crankshafts

Anyone know why none of the aftermarket manufacturers offer a 3.800 stroke crank that can be used with 5.85 rods? Scat, Callies, Eagle, ect, none of them seem to off this, but they do in the longer and shorter stroke cranks. All I see for the 3.800 stroke requires minimum 6.00 rods.

"..............what, and get out of aviation??"
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post #2 of 8 (permalink) Old Jan 26th, 09, 04:59 PM
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Re: 412 SBC crankshafts

the lower price cranks like you listed counterweight will not clear piston pin boss they need the dia. to balance without high cost metal @mallory.
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post #3 of 8 (permalink) Old Jan 26th, 09, 05:03 PM
 
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Re: 412 SBC crankshafts

I'd offset grind a stock 400 SB crank up to 3.8"s, use SJ 6" rods and then figure out a piston to put her together unless you are going to really beat on her??

This is the poor-man's way a doing this is all..

pdq67



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post #4 of 8 (permalink) Old Jan 26th, 09, 07:27 PM Thread Starter
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Dave
 
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Re: 412 SBC crankshafts

Quote:
Originally Posted by ssdoug View Post
the lower price cranks like you listed counterweight will not clear piston pin boss they need the dia. to balance without high cost metal @mallory.
Doug I guess I wasn't clear in my question. Most of the manufacturers offer 3.875 stroke and 3.75 stroke internal balanced 400 block based crankshafts for use with a 5.85 connecting rod. For some reason no one seems to offer the 3.800 stroke in a 5.85 minimum rod length.

Reason I'm asking is a have a new set of KB premium forged pistons left over from a 377 build that I abandoned and my block has been cut to a 9.00 deck height. With my 1.261 comp height piston I have a few options, unfortunately most are destroked, 3.25 crank and 6.125 rods, 3.00 crank and 6.250 rods, 3.48 or 3.50 crank and 6.00 rods (which I just sold the crank and rods for and it already had the Mallory plugs installed to balance a 735 gram set of Bowtie 6.00 rods) or 3.75 or 3.80 crank and 5.85 rods. I can't go 3.875 with these pistons, no off the shelf rod will work. Maybe I'll sell the pistons and just go with a complete new 3.875 stroke 421 rotating assembly.

"..............what, and get out of aviation??"
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post #5 of 8 (permalink) Old Jan 27th, 09, 03:16 PM
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Re: 412 SBC crankshafts

sorry
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post #6 of 8 (permalink) Old Jan 27th, 09, 04:57 PM
 
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Re: 412 SBC crankshafts

Sorry Dave, didn't look who posted, my bad..

I know you wanna beat on her so a cast crank probably won't do you good for very long above 7500 rpm.

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post #7 of 8 (permalink) Old Jan 28th, 09, 12:11 AM Thread Starter
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Dave
 
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Wink Re: 412 SBC crankshafts

Doug no need to apologize, my bad. I read my post and realized it was a little vague as to what I was asking. Good info you posted, I just wasn't clear when I posted.

Paul yes it's got to be forged throughout. Boy it's expensive trying to push a 3.48 stroke motor hard when you're used to shorter strokes. Give me back my 302 days, nothing hurt them. Now I'm leaning towards going 3.875, I'm going to have to change my ways a little bit.

"..............what, and get out of aviation??"
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post #8 of 8 (permalink) Old Jan 28th, 09, 04:33 PM
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Re: 412 SBC crankshafts

keep us posted on your build thanks Doug.
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