When is an engine considered a small block or a big block?

Question

What is the cutoff size for a small block engine, and when does it become considered a big block?

Answer 1

CHEVY'S - YOUR SMALL ENGINES 302,307,305,327,350,400, AND OTHERS ARE SMALL BLOCKS, IN THERE YEARS THESE WERE THE BASE MODEL ENGINES. THE LARGER ENGINES 396,454 AHH WHAT EVER-YOU KNOW, THESE WERE THE ENGINES THAT WERE APPROVED FOR THE CERTAIN YEARS TO BE INSTALLED IN WHAT THE MANUFACTURERS CALL SPECIALTY CARS.

-PONTIAC'S REAL EASY. 1966 LEMANS 326 (SMALL BLOCK) 1966 GTO (SPECIALTY CAR) W/389 (BIG BLOCK). LATER GTO'S GOT THE PONT 400, CONSIDERED BIG BLOCK BECAUSE OF THE CAR IT WAS IN... BY THE WAY THE MUSCLE CAR ERA WAS STARTED BY PONTIAC WITH THE GTO!

-OLDSMOBILES - ANOTHER EASY ONE '64,'65,'66, & '67 F85 OR CUTLASS' CAME WITH THE 330 (BASE MODEL ENGINE) 442'S CAME WITH THE 400 (BIG BLOCK). OTHER LARGE CUBE ENGINES WERE ALSO REFERED TO AS BIG BLOCKS AND WERE USED IN EXTREMELY SPECIAL CARS LIKE THE HURST OLDS. '68 & '69 H/O'S HAD 455'S....

BUICKS THE SAME THING... CADILLAC - I THINK THEY ONLY CAME WITH LARGE CUBE ENGINES, BUT THEN WHEN DID THEY START MAKING A SMALL OR MID SIZE CAR?

THE REST ARE ALL THE SAME - FORDS, CHRYSLERS, ANY MANUFACTURER THAT MADE A MIDSIZED CAR AND WANTED TO PUT A LARGER ENGINE IN IT.

IN THE MID 60'S THE GOVERNMENT WOULD ONLY ALLOW NO BIGGER THAN 400 CUBIC INCHES FOR THOSE SPECIALTY CARS, THAT'S WHY THE HURST OLDS (455) WERE SO SPECIAL, AND THOSE COULDN'T BE FULLY PRODUCED BY GM, THEY HAD TO BE FINISHED BY GEORGE HURST TO BE SOLD TO THE PUBLIC.

Answer 2

That would depend on the engine. Pontiac used to track pretty close to Chevy. So, the equivalent of the Chevy 283, the 305, the 327, and the 350 were usually considered small blocks. The equivalent of the 396, the 427, and the 454 were big blocks. None of those are around any more, by the way, at least not in new production vehicles. A lot of cars used to be able to be built with either the small-block or big-block. The main difference in dimensions was the length of the big-block. That's why on older Firebirds, for example, you'll see a lot of space between the engine and radiator if you have the small-block engine.

Answer 3

It varies from car company to car company. It's kind of simple, in a way- a small block has a smaller block (i.e. the main, big iron piece that holds all the internal parts). A big block is bigger than a small block. But there aren't always clear definitions or limits. For example, you can build a Chevrolet 427 small block, using a 400 core (the main element part of the engine)- but there is also a 427 Big Block, as well.

Generally speaking, with Chevy motors, 400 cubic inches or greater is usually a Big Block (they sometimes call them Rat motors). 400 or smaller is generally a small block (sometimes affectionately called a 'mouse' motor).

Like I said earlier, 400 is not a magic number. Ford has different engine sizes from Chevy, although some happen to be very close in size. Ford has the popular 302 small block. Then there is a 460 Big Block Ford.

Sometimes, the engine size is measured in Liters, as opposed to Cubic Inches. The Ford 302 is sometimes called a 5.0 Liter V8. The Chevy 350 engine is sometimes called a 5.7 Liter V8 engine.

But basically, the Big Block engines have more power and torque than small blocks. There are exceptions, though, like if small block engines are built and modified for drag racing, etc. But in general, Big Blocks have lots of power.

Answer 4

OK, I'll make it short and simple. It is just what it says it is. A small block is small, and a big block is big. If you measure a small block, all of the dimensions are small in comparison to the big block. The big block out weighs the small by some 100+ pounds. Bore doesn't have much to do with it!! Proof is; you can buy a 454 and larger small block. When comparing the two; the heads on a big block are much wider and longer. The height of the big is taller than the small. The big thing is the weight!! Nothing more, nothing less. I see a lot of people voting down the answer of one is big and the other is small. I regret to inform them, but these people are right!! I have built more of these engines than most of you guys have seen. I don't care if you vote for me or not, but some of these people on here with the correct answer are getting hosed on the deal. If you don't truly know the answer, then don't assume these guys are wrong, and vote them a thumbs down. I "know" what I'm talking about, and will bet the farm on the answer, but I'm not the first to have the correct answer, and you guys are voting thumbs down on correct answers!! You need to get your facts straight BEFORE you vote them down!!! Some of you are confusing a short block and a long block with a big and small. I have never saw so much mass confusion.

Answer 5

This Site Might Help You.

RE:
When is an engine considered a small block or a big block?
What is the cutoff size for a small block engine, and when does it become considered a big block?

Answer 6

The terms "small block" and "big block" have to do with the physical size of the block, not the cubic inch. For instance you can have a 427 ci small block Chevy and a 427 ci big block Chevy. But, the big block Chevy is dimensionally larger then a small block and all the parts except the distributor are different. A good example of this is the 400 ci small block Chevy and the 396 ci big block Chevy (which later became the 402 ci big block Chevy). Nearly the same cubic inch, but completely different engine blocks and cylinder heads.

Same goes with Fords. The 260, 289, 302, 351W, and 351C are considered "small blocks", the 400M is considered a midland block, the 390 and 428 are big blocks as are the 429 and 460.

Pontiacs are a bit trickier since they kept the same block from 326 through 455, the only changes being bore and stroke. The 428 and 455 are considered "big blocks" because they use a larger crank main journal then the 326, 350, 389, 400, and 421, but the block is dimensionally the same externally.

Answer 7

the cut off size for a small block engine
is 6 cylinders.
anything smaller would not be a small block.

now when it comes to big blocks,you can get an 8
cylinder in a big block and a small block.

Answer 8

The physical size of the block. There are small block V-8s anywhere from 265 to 400 cubic inch displacement. The best way to answer this is to actually look at the big block next to a small block. Go to any car show and I'm sure there will be someone there who can point out the different sizes.

Answer 9

When I blew up my engine in my car they asked me if I wanted the small block or the big block and this is how the Ford garage described it to me. The small block is basically the guts of the engine(new block & new heads). The big block was the whole engine(new everything clear down to the oil pan). The cost difference was about $2000. I went with the small block because it was cheaper. Should have went with a big block because we've had problems with oil leaks ever since(7 years) and they can't figure it out. Finally traded it in on a new car. Live and learn!!

Answer 10

The size of the block. There is no cubic inch cut off a 396 is small a 400 is big and a 402 + are all big blocks 350 and below all small blocks.

Answer 11

well really it has nothing to do with cubic inches at all there is a 348 big block (where the 409 came from)400 small block,396 big block,427 small block,it really is the size of the base engine block,the block casting.when youre past a certain diameter on the cillinder it is concidered a big block or if youre under a certain size in diameter its a small block.So truly it has nothing to do with cubic inches or bore and stroke.There is virtually no cutoff size for a small block it can go down to 268 and up to 427ci.P.S. there is also a 427 big block and a 400 big block.