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Old 06-17-2001, 08:55 PM   #1
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BBC casting #'s.......??

IU just bought a complete engine from a known racer here in town and was told that the motor was a 454 Chevy, but the info that I'm getting from the net is that it's a 396. Can someone please correct. Here are tha casting #'s 3969854..

thanks..

BTW: wich flexplate do these use (i need to know to get me a starter) and if they are internally or externally balanced (need to get a dampner too!)

[This message has been edited by Baz89RS (edited June 17, 2001).]
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Old 06-17-2001, 09:14 PM   #2
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3969854....402.......70-72...2 or 4 bolt

That came from www.mortec.com. The 402 is a 396 bored .031 to 4.125 from the factory. For our purposes (I have one too) it's just a 396 with one less overbore availible. The plus side of the block is some of the older 402's have thick walls and will live happily at larger bore diameters.

You might check the crank #'s and make sure that it is a 3.76 stroke crank. It doesnt take much to put a 454 crank in a 396 block.
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Old 06-18-2001, 01:08 PM   #3
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Thanks man,
I'll drop the pan to check the crank #'s out. what does a 454 crank make the engine?
the motor ran mid 11's in an el camino so it should be something strong. I'll post back as soon as I get a chance to drop the pan.
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Old 06-18-2001, 03:02 PM   #4
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Could be a 396 block with a 454 crank overbored to 4.25". Some 396 blocks are thick enough for this, but if it is he's still cheating you a little.
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Old 06-18-2001, 06:39 PM   #5
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If that thing is bored .156 the walls would be paper thin, I couldn't imagine taking anymore off. I'm not saying it isn't possible, but it is highly unlikely.

When you take the pan off, look at the pan rails on the sides. To put in a 454 crank you need to grind clearance into those areas for the counter weights. Off the top of my head a 454 crank (4.00" stroke) and a 402 block (4.125+ any over bore) would be around a 425 CID. It wouldn'd be a 427 as we know it, thats a 3.76 stroke and a 4.25 bore, (e.g. 396 crank + a 454 block).
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Old 06-18-2001, 09:37 PM   #6
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My books list that casting number as a 396 from 69-72 or a 402 from 70-72

Easiest way to check the crank to see if someone tryed to stuff a 454 crank into it is to look at the balancer and flex plate. A 454 is externally balanced and will have the offset balance on balancer and flexplate.

I doubt it's a 454. It's too much work getting the crank to clear and to bore out the block that much. It's cheaper to find a 454 block.

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Old 06-18-2001, 09:37 PM
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