What makes an engine a big block or a small block? Is it the cubic inches or is it something else?

Thanks

 

Not this again...

BB/SB WAS a way to id engines "back in the day".

That day was when you had a 327 or a 396 in your Corvette--BB or SB.

Or, a 289 or a 390 in your Mustang.

There are others. But it described the relative size compared to other engines from a manufacturer, and as long as manufacturers had two engine series, you had a fair idea what was what. (But a fair idea only, as the next question would be "..'nine 6 or 427?.." in the case of the Corvette....later 390 or 428 for the Mustang, and in '68, 289 or 302 for the SB...it goes on and on you see....)

That's one.

The other is deck height of the block. 10" is the arbitrary number selected by Hot Rod Mag & I suppose others. Note that the BB Chev 396/427 are just under 10", but it's clear they are the BB compared to the 350....

Then you get to Ford. There are more engine series at Ford, so BB of SB won't help. There are 4 engines with a bore/stroke of 4 x 3.50. By deck height, one is a SB, three are BB. So the term won't do you any good, you have to know which one you have.

Check out the deck heights here for Ford engines--it's the right hand column:

Kelly hotrod - Ford Engines Page 1

And BB/SB will do you no good for bell pattern for Ford either, as there are almost as many bell patterns as engine series. A C6 had to have several bell housings to fit on all the engines it was bolted to over the years.

I expect the next post to say "it's a Chevy thing..." If so, scroll to the engine forums and find this very site using the terms.

 

Nice link!

I agree that it's a pretty vague concept these days -- as much tradition as anything else.

I think that, for a while, the thought was that a BB had more room to grow -- there have certainly been some monster displacements. SBs had more restrictions, although they have built up some fairly large ones -- supposedly with decent reliability.

And, as far as I know, it's a generic concept -- they even talk about BB/SB mopars in the hot rod mags. The Chebby thing is mouse (350) and rat.

 

Across the board, it generally refers to cubic inches and engine block family. About 360 cubic inches is the largest we call a small block. Some engines with large blocks had small cubic inches though.

Ford- It was generally obvious to tell the difference between a 302 (SBF) and a 460 (BBF).

Chrysler- Back in the old days a 318 almost looked a lot like a 383 block until the foundries began pouring smaller engine blocks around 1966 or ’67.

Chevrolet- There was always a notable difference between the 348/409 motor family and the 265-327 engines. When 396/427/454 motors were out, a notable difference still existed between the 327/350 blocks.

Buick, Pontiac and Oldsmobile- Their smaller displacement motors were generally 350 cubic inches, but used the same castings as the 400 and 455 cubic inch motors of the their brand’s engines.

Hope this helps!

 

I know you listed other info, but Cubic Inch Displacement has nothing to do with BB or SB.

A 265 chev has the same outside block dimensions as a 400. Same deck height: small.

A 330 FE has the same outside block dimensions as a 428. Same deck height: big.

It is true the "big block" has more room, due to deck height, cam height etc. So while you can get the "small" motors out to even 440 for the Chrysler, the BB 440 or 460 or 454 will go well into 500+ inches.

 

Thanks for the responses. I thought it was the displacement of the engime but I guess you can learn something new everyday.

 

It was generally about bore spacings. Deck height is not a reliable indicator, either. Pontiac only had one basic V-8 engine, regardless of displacement. The easiest to spot are the Mopars, with rear distributor on the "SB" 273-360ci and front distributor on the "BB", 361-440ci, wedge or hemi.

With Ford, I generally think of the Windsor series of engines as being small block, but didnt the 351W have a taller deck? What would you call the Modular V-8s and V-10?

Jim

 

Wider bore spacing and taller deck height, with one you usually get the other.

351w and c are under 10" deck height, sb. 351m, and 352 FE, over 10".

Hhhm. I had that wrong earlier.

 

Generally the understanding was anything over 360 cubes was a big block. This is what the experts say: Cylinder block - Wikipedia, the free encyclopedia

Yes the 351W (SBF) did have a taller deck than the 260/289/302 block. The difference is about 2-inches. This often forces Fox Chassis owners into a raise style hood after a 351 conversion is done. Then again, the 351 can be bored and stroked to like 426 cubes, but is a factory small block.

It looks like the 351C was considered a mid-block.
Ford 335 engine - Wikipedia, the free encyclopedia

The Modular 4.6 motors are Pigs! Huge engines with like 281cubes! LOL

This is pretty educational! Next question!

 

I would not put to much faith in the wiki stuff - i wrote a lot of it ;-)

but most ofthe posters are right on - the blocks were larger in many ways, bore spacing (which begats some big bores) and deck heights.

Ford, techincally has very small block, small block, medium block, kinda big block and really big block (via odd fate, the really big block is the tritons - larger than the 460 and diesels when assembled!)

thru the miracles of bores and strokes we have 454 small blocks, which used to be large for a big block, and 700 inches for big blocks.

 

Yup a 4.6/5.4 is as nearly/just as big as 460 with much less displacement. Mostly due to the over head cams.

 

[quote=Flexfuel-Dave;6845615]Generally the understanding was anything over 360 cubes was a big block. This is what the experts say: Cylinder block - Wikipedia, the free encyclopedia

OK, so don't get me wrong, I'm not beating on you, just this dead horse.
"Experts" on Wiki? They site Motor Trend. Give me Car & Driver or Hot Rod for tech stuff over MT. Cylinder displacement is meaningless here. We are talking about the physical size of the block regardless of displacement.


Yes the 351W (SBF) did have a taller deck than the 260/289/302 block. The difference is about 2-inches. This often forces Fox Chassis owners into a raise style hood after a 351 conversion is done. Then again, the 351 can be bored and stroked to like 426 cubes, but is a factory small block.

Read the link I posted:

Kelly hotrod - Ford Engines Page 1

289/302: 8.206
351W: 9.480 or 9.503, less than 1 1/2". OK, we'll round up.


It looks like the 351C was considered a mid-block.
Ford 335 engine - Wikipedia, the free encyclopedia

"Mid-block"?
351c = 9.206, so midway between the 302/351W? Still SB.

The Modular 4.6 motors are Pigs! Huge engines with like 281cubes! LOL

Pigs? Maybe, and they are very large. SB = 4.6 with deck at 8.937. BB is the 5.4 with deck at 10.078. However, not even I, as obsessed with deck height as I am, am going to call them sb or bb. 4.6 or 5.4. And despite the "Modular" name, it appears there are Romeo and Windsor versions, with limited parts interchangability between them. So, I predict other names will come forth for these engines as they age and people find out that parts from one won't fit a seemingly indentical other....



This is pretty educational! Next question![/quote]

 

Believe it or not, a guy on the ranger forum was able to squeez a 4.6 into a ranger. He wanted to do something different than the run of the mill 5.0 swap. I don't know how, but he got it to fit, he even had pitures.

 

Did he put the heads on it yet?

 

Yup, whole engine was in there and wired up. From what I remember he had to go to a junkyard and get a steering box off a nissan because it mounted in a different manner