Definition of big block vs. small block

[Musclecarclub]

I have never seen a really good explanation for the difference between a small block and a big block. I mean, obviously a big block is bigger, but what is the dividing factor? What was/is the largest small block and smallest big block? Any ideas?

[Blue02R6]

I always thought they were differentiated in that way when a company/division had two different sized blocks, with the smaller one being a small block and the larger being a big block. It would seem, however that few share this opinion with me.

[TorinoGT69]

I would pretty much agree with Blue02R6.
Cubic inches has nothing to do with it really. Example: 400cu chevy is a small block - 396cu is a big block. The difference is the type and size of the block.

[-The Stig-]

Well seeing as of lately you can now buy 454ci Small Blocks from MoTown.

Basically, as mentioned above actual displacement doesnt matter much now with all the new stroker kits.

But what makes them a big block is just the size of the actual block and internals.



I still want a 427BB, nothing like turning 9,000rpm with a big block. Just to show the import guys who think they're the only ones with high reving motors.

[Blue02R6]

Originally posted by RedNeck383
I still want a 427BB, nothing like turning 9,000rpm with a big block. Just to show the import guys who think they're the only ones with high reving motors.

I'm drooling. (Now I just need a chevy to put it in.)

[Musclecarclub]

Cubic inches doesn't matter. Having two types of blocks doesn't matter. What is the definition? This is definitely a tough question.

Here is one website's (chevytrucks.com) definition, which seems to agree with the previous answers:

Small Block: The smaller of a manufacturers two series of engines. In the case of Chevy, the small block includes the 262, 265, 267, 283, 302, 305, 307, 327, 350, and 400.

Big Block: The larger of a manufacturers two series of engines. In the case of Chevy, the 366, 396, 402, 427, and 454.

[73superduty]

A tough question for sure on a great explanantion, however, if you were talking just Chevies, then the previous answers would be just fine. However, let's talk old school and Pontiacs.
Pontiac engines utilize the same block from the 326 all the way to the 455. So when someone says big block Pontiac, it isn't true.
The only difference is the size of the journals in the block thus giving it the cubic inches nomenclature.
Take a minute once and look at a 350, 400 and a 455 and you'll see the basic engine block for all of these cars.
If we go by what has been posted here, then yes the 400 and the 455 would be big blocks. Pontiacs call it standard. They just play with the internals.
Chris

[TorinoGT69]

You could kinda say a 301 is a small block pontiac.

[73superduty]

Originally Posted by TorinoGT69

You could kinda say a 301 is a small block pontiac.

I'll agree with that, but it doesn't match the "standard" Pontiac blocks, thus why I didn't include it.
Kind of the red-headed step child engine of Pontiac.
Chris

[Blue02R6]

When I talk about Pontaic motors, I've always corrected people about them calling the motor a big block. I thought my answer took this in to account, but it's all in how one interperates it. The 301 is typically not called a SB because it was only a 301.

[Pacfanweb]

Originally Posted by 73superduty

A tough question for sure on a great explanantion, however, if you were talking just Chevies, then the previous answers would be just fine. However, let's talk old school and Pontiacs.
Pontiac engines utilize the same block from the 326 all the way to the 455. So when someone says big block Pontiac, it isn't true.
The only difference is the size of the journals in the block thus giving it the cubic inches nomenclature.
Take a minute once and look at a 350, 400 and a 455 and you'll see the basic engine block for all of these cars.
If we go by what has been posted here, then yes the 400 and the 455 would be big blocks. Pontiacs call it standard. They just play with the internals.
Chris

Actually, the 400 and 455 have different bearing sizes, so the 400 would not be included with the so-called Pontiac "big blocks".
400 internals are same as 350, 389, etc.
I think the 428 and 455 are the same, and maybe the 421.

[galaxie500fb]

how about fords doing. a 351 is considered a small block but a 352 fe is called a big block. just 1 cubic inch difference.

[Musclecarclub]

That must be one cubic inch. Actually, it seems to follow the bigger/smaller engine in a manufacturer's engine series, rather than the actual size theory.

[PWMAN]

Originally Posted by galaxie500fb

how about fords doing. a 351 is considered a small block but a 352 fe is called a big block. just 1 cubic inch difference.

Well there is a bunch of different 351's. The 351 Cleveland, modified, and Windsor. The windsor is the small blcok because it is much like the 302. The Modified is more of a big block, and the cleveland is a league of it's own. There is no distinction between SB and BB for the cleveland, it's just a cleveland and thats it.
The 352 is a FE blcok like you said, completely different than anything else Ford makes. The FE block include-330, 352, 390, 427 L/M/H riser, and the 428. The 429 is also completely different than the 428 FE.

As for a basic distinction between SB/BB, my guess would be it's that deck height that determines between a SB and BB. Or it could be just as simple as the actual size of the bare block itself.

[GTStang]

the 302,351W,351C,351M, the always forgotten Ford 400(the missing link).

A 302 and 351W are small blocks. But also note that a 302 and a 351W are different blocks due to the 351W's taller deck height.
Now the 351C,351M, and Ford 400 are all actually the same block except that the 351M/400 have larger crank journals, also they are all big blocks.
The cleveland came first, then Ford wanted to use the block in trucks and passengers cars so the stroked it to 400 and changed the mains and ditched 4V heads. All this to make more torque at lower rpm's more suitable for a car/van/truck. Once the gas crunch hit they destroked the 400 back to 351. It was a modified 400 hence the name 351M.

I don't know about Chevy/Mopar etc.. but I know why Ford has such a messed up line is purely cause of History. Once you know the chronological order you understand.