small blocks and big blocks?

At what size engine does a big block techincally start? ive been told that it is 350 but i know it is wrong because then my car has a big block in it and i know its a small block. also when was the first big block made available to the public for aftermarket purchases?
thanks in advance this will hopefully win me a bet.

The terms relate to engine design, not displacement. Some domestic manufacturers produced pushrod V8 engines using two completely different designs. Often, one was physically larger so it was called a big block.
Therefore it is possible for the largest displacement small block to have more displacement than some big blocks. For example, the Chevy 400 was a small block design, while the 366 and (early) 396 engines were big block designs.
(Later 396 engines were actually 402 cid)

Big Block/Small block is a chevy thing. Its not a displacement thing... Fords are often referred to as 'big block' and 'small block', incorrectly. You can't do it by bore spacing since Ford has more than 2.. what would the 3rd be? Middle block? You certainly can't do it by displacement, because you'd have 351m's and 400's, which use the same block, and 352-428FE's which all use similar blocks.. If you made the cutoff point at say, 375ci, then you have a 351m small block and a 400 big block, 352FE small blocks and 390FE big blocks! It just doesn't work. Chevy just pointed at a series of block that was physically bigger and said "Big block!" then pointed at their smaller block and dubbed it "small block". Ford did no such thing. Ford literature never refers to their blocks as 'big blocks' or 'small blocks'. Ford has the Windsor series(289/302/351w), 335 "cleveland" series(302c, 351c, 351m, 400), 385 series(429/460), FE series(352, 390, 410, 427, 428, etc), and so on. It really annoys me that people use SB and BB to refer to Ford. I own a 351c, which has the same stroke, bore, and bore spacing as a 351w, so its the same basic block design, but few parts interchange - when I'm looking at a product and it says "Fits SBFs", I don't know if it'll fit mine or not. Some companies refer to clevelands as small blocks, most refer to them separately as clevelands(windsor series is called small blocks by most), and some even call the cleveland a big block! Which is laughable. Unless you go by valve size... :evillol:

Its not a chevy thing....

olds denoted thier big/small block based on the amount of decking taken off.

and ford certainly does notate big vs small - just look in the motorsports catalog. (and not to mention the windsor comes in 2 sizes itself, the 289/302 blocks are different from the 351)

....oldsmobile and chevy are one in the same

....oldsmobile and chevy are one in the same

they are?
you might wanna check into that....

they both are the same as in they are both produced by gm.

If your motor is bigger in physical size than other V8's by the same manufacturer then you have a big block. If other folks have engines bigger than yours then you have a small block. My Ford 302 (not boss) was a small block. My Mopar 413 Wedge was a big block. My 2.0 Cavalier must be a micro block.