[Byfield]

Would all GM big blocks be based upon the same casting, and thus, be the same size (in exterior dimentions)? i: The Buick 455 and the Chevy 454? or the Caddy 500?

Thanks, Kurt

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The 68 Chevelle info page. [last updated Nov. 30, 98]
www.geocities.com/MotorCity/Garage/6873/Chevelle/68_Chevelle_Info.html
The Team Chevelle Showroom. [last updated May 17, 99]
www.geocities.com/MotorCity/Boulevard/6987/
Email: [email protected]
A.C.E.S. #1352

 

[Chevguy68]

I am inclined to say no. I believe that there are size differences. I could be wrong though. By the way, great home page!

-----Jerry-----

 

[Aug98]

No, they are not all the same size. The biggest diffrence in Chevrolet is between the truck block and or the tall deck bow tie block and the passenger or regular deck big block. As far as the other two, they are diffrent animals.

[This message has been edited by Aug98 (edited 05-24-99).]

 

[Tom Mobley]

Kurt, no they're different across divisions. I think the Buick 455 is lightest, doesn't weigh much more than a SBC. In general, they're of similar size, as they were interchangeable between A-bodies.

TOm

 

[DZAUTO]

Aug 98 is correct about Chev BB, but the difference is in deck height only. Because the truck BB has a taller (about 1in) deck, that makes the heads further apart. Although everything will still bolt up. You either need a wider intake manifold or install spacers between the head and intake and between the intake and top of the block.
Chev BB and SB engines are 2 completely different engines, but with the Olds BB and SB, they just raised the deck to create a BB. Thus, if you want to swap a 350 Olds with a 455 Olds, you just remove the accessories, unbolt the exhaust manifolds, pull out the 350, drop in the 455 and bolt everything back up, basically. Wish it were that easy with Chev SB to BB swap. Chev also has it's own bell housing bolt pattern. Whereas Olds-Buick-Pont share the same bell housing (and I think Cadillac also). As was mentioned before, A bodies have a lot in common. For example, if you had a super nice Cutlass or GTO and wanted to install a Chev BB, all you need to do is bolt in the Chev motor mount brackets (the holes are already there). Or, you could bolt an Olds W-30 455 into your SS454 Chevelle. Excuse me, not interested in this one? Sorry!

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[Aug98]

Hey DZ don't forget the distibutor, also your headers won't fit in the same place. And if you have headers that have a tube that wraps around the frame on each side like mine do it also presents a problem. Not really a like for like block, pain in the rear really.

[This message has been edited by Aug98 (edited 05-24-99).]

 

[DZAUTO]

That's why I added the word "basically" at the end of the middle sentence. I didn't think I should get into a long explanation about other GM motors at this site. You know it's against the law for us to get sidetracked from Chevelles here. That's why none of us EVER do it.

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[Dave Birdwell]

While we're nitpicking,

the difference in the deck height is only .400" The standard block is 9.8", and the truck block is 10.20"

 

[DZAUTO]

Dave is absolutely right. When I said the truck block was about 1in taller, I had Olds BB on the brain. The Olds BB (455) is about 1in taller than the Olds 350.

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[jaqazi]

Does a tall deck truck block allow a longer stroke? If you milled it down .4 inch would it work the same as a short deck block?

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Jameel Qazi
#'s 67 SS

 

[Tom Mobley]

Jameel, it allows more room between the crank and the deck, usually ends up with a longer rod or stroke or some combination of the two.

No, you can't deck it .400, the deck surface is not that thick, you'd mill the whole ddeck surface off, be looking at water.

Tom