I have always wondered what the difference between a big and small block is. I know there is a Chevy 350 small block and a Chevy 350 big block. Also the old 427 was a big block but the new 427 ls7 is a small block so obviously it has nothing to do with displacement.

If I had to take a guess I would say it has to do with stroke and bore. A small block has a smaller actual block so it can’t have that big of a bore and therefore requires a bigger stroke to acquire the same displacement as a big block. The big block has a physically bigger block so it can have a bigger bore and smaller stroke and still achieve the same displacement as a small block with a bigger stroke.

So what is the real difference between the two?

 

one block is bigger than the other, it's pretty much how it sounds

has nothing to do with displacement, think of it as a family of engines

for the most part i can't swap parts from my small block 360 to my big block 440 due to different dimensions of the actual block. The small block stroker engines are what cause most the confusion. Some of these stroker blocks have as much displacement as the big blocks.

hope this helps, can't really think of a better way to explain it.

 

Its kind of complicated.


Chevy V8s are probably the most common so I'll use them as an example. A 305, 327, 350, 383, 389, 400 are all examples of small block V8s. A 427, 454 and 502 are all examples of big blocks. The differnent dimensions within a certain family of blocks comes from the bore and stoke. This can also be affected by the size of the crank, pistions and heads.

a big block is always going to have a overall larger exterior size than that of a small block and will always have more possibilies for bigger displacement than that of a small block counterpart.

Another example of this is with Ford modular engines. The 5.4 liter V8 block used in the F150s and Expeditions is the same general block used in my Mustang. Just different bore and stroke. etc. etc.

This is really difficult to explain, but I did my best.

 

You know, as much as I like to think I'm one of those "car people", I've never really known what the difference is. I've always just thought of it as being a different family of engine. Much like Honda has the B series and H series. You can get a B series up to the same displacement as an H series but it's still a different motor. The H series would be the equivolent of Honda's big block. The domestic companies just refer to them as big blocks and small blocks instead of a certain series.

Good question.

 

SBC-siamese center ports on the heads.
BBC-evenly spaced.

basically, it refers to the size of the block.

lingo definitions:
mouse-small block
rat-big block
elephant-Hemi

better now?

 

your right you answered your own question

 

Isn't there a difference in spacing from bore center to bore center?

 

Why the fuck do you go around digging up old ass threads?

 

No matter how many old threads you bring back, it will never be Drag again.