400 SBC crankshaft

General engine tech -- Drag Racing to Circle Track

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GARY C
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Re: 400 SBC crankshaft

Post by GARY C » Thu Oct 19, 2017 10:34 am

rfoll wrote:
Thu Oct 19, 2017 9:41 am
68post wrote:
Thu Oct 19, 2017 1:24 am
rfoll wrote:
Wed Oct 18, 2017 8:57 pm
I ran a .060 over 400 block for several years. I knew it to be strong enough because the previous owner destroyed some pistons using nitrous, and the block held up. Some blocks are OK for this others will have problems. Be reasonable with your expectations. I got to low 11s @120 in a 3200 lb. car with mine, but I started worrying about driving over the crank at that speed. Get your block decked square and honed with a plate to give yourself a chance of a good seal. Thin rings will help seal the thin bore. Don't put any exotic parts in it in case the block fails. I used the standard Scat rods and KB pistons and never had any problems. 412 inches will make plenty of power even if you only spin it to 6000 or so.
They like a lot of cyl head at 412 and 6,000. What were you using ?
I'm using Track 1 Spec heads. I got them really cheap bare and added my own components. They were big enough for 6500 rpm or so, but they will get retired soon. The block fill is a very good idea.
Can you do block fill after final machineing?

mark_follweiler
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Re: 400 SBC crankshaft

Post by mark_follweiler » Fri Oct 20, 2017 6:35 pm

GARY C wrote:
Thu Oct 19, 2017 10:34 am
rfoll wrote:
Thu Oct 19, 2017 9:41 am
68post wrote:
Thu Oct 19, 2017 1:24 am


They like a lot of cyl head at 412 and 6,000. What were you using ?
I'm using Track 1 Spec heads. I got them really cheap bare and added my own components. They were big enough for 6500 rpm or so, but they will get retired soon. The block fill is a very good idea.
Can you do block fill after final machineing?
no.

Ks Fats
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Re: 400 SBC crankshaft

Post by Ks Fats » Fri Oct 20, 2017 8:45 pm

Past experience has shown the stock block to be the weak link; when we were forced by rules to run them in circle track applications doing the half fill and splayed cap drill only delayed the failures. The stock maincap bulkheads failed before anything else. I'd be looking for an aftermarket block.

rfoll
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Re: 400 SBC crankshaft

Post by rfoll » Sat Oct 21, 2017 9:12 am

You never said exactly what you were going to do with the engine other than put it in a Camaro. If it's a mild street strip application, it will live for a long time. Once you start building engines that require race gas and sustained high rpm, the life diminishes.
So much to do, so little time...

LaVelle
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Re: 400 SBC crankshaft

Post by LaVelle » Sun Oct 22, 2017 7:40 am

Ks Fats wrote:
Fri Oct 20, 2017 8:45 pm
Past experience has shown the stock block to be the weak link; when we were forced by rules to run them in circle track applications doing the half fill and splayed cap drill only delayed the failures. The stock maincap bulkheads failed before anything else. I'd be looking for an aftermarket block.
Agreed on an aftermarket block being the best route.

It will be curious to see what some of the engine builders think of this. ( probably not cost effective)

With the main web bulkheads being weak as they are, drilling for 4 bolt mains (splayed or not) weakens them further.
Wouldn't it be better to half fill a 2 bolt block and stud it with a main cap girdle.
The rear cap is a weak link as it is with the large main bearing size.

Head studs wouldn't be a bad idea either.

mdabbott2009
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Re: 400 SBC crankshaft

Post by mdabbott2009 » Sun Oct 22, 2017 8:41 am

Stock 400 virgin block never touched drove in trailer didn’t smoke or knock found this
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rfoll
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Re: 400 SBC crankshaft

Post by rfoll » Sun Oct 22, 2017 9:14 am

"It was running good when pulled...
So much to do, so little time...

cgarb
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Re: 400 SBC crankshaft

Post by cgarb » Sun Oct 22, 2017 10:45 pm

Probably one too many times of drive down the road, shut the key off, pump the gas a few times and boom! Blow the thrush muffler open like an old beer can...lol.

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