how do u know if its a big or small block?
Thread Starter
Racer
Joined: Sep 2001
Posts: 304
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From: honolulu HI
how do u know if its a big or small block?
i know this is a stupid question but what are the exact differences between a small and big block? when does a block become big? 350 engines are small blocks so what size determains a big block? 400+ or what? :confused:
Melting Slicks
Joined: Jun 2001
Posts: 3,281
Likes: 6
From: NC USA
Re: how do u know if its a big or small block? (1980 razz)
Appearancewise, quickest way I know to tell GM big blocks is that they have much bigger and wider valve covers than the small blocks and the 2 center tubes of the 4 exhaust manifold/header tubes on each side of a small block are close together whereas on a big block the 4 tubes are evenly spaced. Displacement is not always the way since there are now 427 small block engines although anything over that I would think would always be a big block.
BIG BLOCKS RULE! :cheers:
BIG BLOCKS RULE! :cheers:
Melting Slicks
Joined: Apr 2000
Posts: 3,341
Likes: 6
Re: how do u know if its a big or small block? (1980 razz)
" . . . what are the exact differences between a small and big block?
Small block engine and big block engines are two seperate and distinct product lines. One is physically much bigger than the other, allowing for more room to tuck in bigger bore pistons and longer stroke cranks, resulting in greater displacement.
"when does a block become big?"
At birth.
"350 engines are small blocks . . ."
Yes. So are 265's, 283's and 327's (in Vettes)
". . . so what size determains a big block? 400+ or what?
Strictly the size of the block casting, not the CID. They have been available in Vettes in 396, 427, and 454.
Small block engine and big block engines are two seperate and distinct product lines. One is physically much bigger than the other, allowing for more room to tuck in bigger bore pistons and longer stroke cranks, resulting in greater displacement.
"when does a block become big?"
At birth.
"350 engines are small blocks . . ."
Yes. So are 265's, 283's and 327's (in Vettes)
". . . so what size determains a big block? 400+ or what?
Strictly the size of the block casting, not the CID. They have been available in Vettes in 396, 427, and 454.
Safety Car
Joined: Jun 2001
Posts: 4,004
Likes: 2
From: Severna Park Md
Re: how do u know if its a big or small block? (Marks69BB)
One thing that seperates them is the big block crankshaft and other internal engine components are bigger and heavier. On the big block, the greater mass of the rotating assembly translates into greater inertia energy which is why, in most cases, big blocks are capable of producing more torgue then small blocks. Like Mark said, comparing the size of the valve covers is the quickest to tell the two apart.
Standard size BB 396 402 427 454 the newer ones come in 502
Standard size SB 305 307(odd ball) 327 350 400
These are standard sizes that have not been bored or stroked. I may have missed a few.
Standard size BB 396 402 427 454 the newer ones come in 502
Standard size SB 305 307(odd ball) 327 350 400
These are standard sizes that have not been bored or stroked. I may have missed a few.
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 99
From: Ontario
Re: how do u know if its a big or small block? (1980 razz)
Good reference for SBs.
http://www.ag.auburn.edu/users/gparmer/sbc.html
http://www.ag.auburn.edu/users/gparmer/sbc.html
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Re: how do u know if its a big or small block? (1980 razz)
Easiest quick way to tell is the small block valve covers are about 4 inches wide....and the big block valve covers are about 7 inches wide....
that will do, untill you get more familiar with them....
that will do, untill you get more familiar with them....
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Racer
Joined: Aug 2001
Posts: 457
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Re: how do u know if its a big or small block? (JYD69_427)
JYD69,
I got a good laugh out of your description of a BB owner ! I might add that if he wears 'Depends' adult diapers....you know what he has under the hood ! :lol: :eek:
I got a good laugh out of your description of a BB owner ! I might add that if he wears 'Depends' adult diapers....you know what he has under the hood ! :lol: :eek:
