exactly like the title says, what are the different of them?
cause some GM motor are like 4.5 liter, but people consider them as small block?

With the V8's I think the difference is in the actual block design, not displacement, but I'm not positive. I think that the largest motor considered a small block is either the 409 or 427, but don't quote me. I also believe that there is a big block that is smaller than those.

long block = complete engine

short block = block, pistons, rods, crank, and everything else under the head

small block chevy = 327-383 cubic inches

big block chevy = 430-500+

stealth is off to a good start, but needs a little help.

a long block is actually not a complete engine. that would be a "complete engine" :D a long block is a shortblock with heads. if you buy a longblock, do not expect to get an intake manifold (and carb, if its not EFI) or any accessories (alternator, ps pump, etc).

big blocks are actually exactly that. BIG. for example, the big block chevy weighs about 200lb more than the small block. yes, even a 396 big block versus a 400 small block. the heads are bigger, thus the valves can be bigger (within reason depending on the bore, combustion chamber and valve angle) and the ports can be bigger. that means more horsepower.

small blocks can be fairly large displacement given the right modifications and aftermarket bits. the venerable 5.0 litre small block Ford starts at 302ci and can go to 347 fairly easily. the 351 windsor can reach somewhere north of 420ci. in the chevy world the old 350 (55-92) can hit about the same, 420-447ci. mopar... who cares. ;)

and of course big blocks can get ridiculously huge. 500, 600, 700ci and up.

this is all the old stuff. when talking modern engines, the Ford modular V8 is actually pretty damned big for the small displacements it uses (3.9 - 5.4L). when comparing cast iron blocks and aluminum heads, it's actually over 100lb heavier than the old 302/5.0L it replaced. it's physically larger in every way too, wider, taller, etc. chevy's new OHC LS1 is roughly the same size as the old small block, but uses a higher camshaft to give shorter pushrods and a different bore & stroke to achieve the old familiar "350" cubic inches. it's a little lighter compared even-up, a lot lighter in all-aluminum format of course.

The designation big block and small block pretty much developed in the late 1950's and early 1960's. The traditional dividing line was some where between 350+ CID to 400 CID inches, and the ability to develop 400 hp or so off the show room floor.

Like ColinL said, these engines as a group also typically had much beefier blocks, heads, cranks and rods, larger oil pumps, etc than the smaller engine families (many componets were shared from engine to engine.)

The bare cylinder heads on my 392 chrysler hemi weighed about 85#, and the bare block was a two man affair to move, but a fit adult could pick up a bare block of a 289 ford or 283 chevy.
If I remember correctly the assembled weight of my 392 was about 650#.

where the small blocks were in the 400# range.

Many of the small blocks were just bored and stroked models of smaller engines. When they went over that 400 CID displacement they typically had to engineer a whole new family of engines as they had run out of room on the small blocks. They typically were of a different production design and series from the small blocks. They usually had different bell housings to accept bigger transmissions and clutches as well.

For the most part the small blocks were also the first light weight V8 designs that used special lightweight casting techniques.

This is where things get a little fuzzy, the AMC 401 block actually weighed about the same as 327, but was a big block both by size and reputation, and was developed into a good power plant.

There was kind of a no mans land in the high 300 cubic inches that were generally considered big blocks but over the years some of the small block designs slowly increased in size and got close to the traditional big block displacements. Some of these used every trick in the book to get maximum displacement that would fit in the block.

These were a group of engines that started below 400 CID, but could make big block power, and usually were the original design size that evolved into the 400+ CID engines, and are generally considered big blocks.


Small blocks
Chevy 265, 283, 327 ( later years the 350 - 383)

small big blocks 348 396
big blocks 409 427 454


Pontiac 389, 400, 421 were all considered big blocks. Can't think of a pontiac small block off the top of my head.

Ford ( not a real fan of Fords so I'm probably missing some)
small block
289, 351 (in later years the 302)

small big blocks 390
big blocks 427 428 429
Lincoln had an even bigger engine I think it was 431 CID


Chrysler
small block
273, 318 340

small big blocks
(354 wedge, 361 old designs that faded away)

383 -- engine in the famous road runner models, base engine for the 440.

(early hemi's 331, 354 were of moderate displacement but had the exact same design of the classic 392 hemi which was always considered a big block. This was the engine that powered the Chrysler 300 series which was the first American V8 rated at over 300 hp)

413, 426 wedge and 426 hemi and 440 wedge. In later years the 383 grew to 400 CID

In the early 1970's new engines came out like the 302 ford and 307 chevy that were built on the old small block castings with different strokes.


Chevy opened the door to a new era with the 454 and started the whole family of monster motors that in race only versions go up into the 600 CID range today.

you will also hear some other related nicknames for some of these engines. The mouse motor was the chevy small block series, and the rat motors were the late model big blocks.

The elephant motors were the 426 CID hemi engines. In some of the race chassis they had to dispense with rubber motor mounts and to control the massive torque of these engines mounted them solid on flat plates bolted to the front of the blocks that were nicked named elephant ears.

Larry

Damn hotrod, thanks for the smack down! I just doubled my knowledge about domestic engines! :D

Ahhhh, domestic talk. How I love it.

quit talking about domestics! it makes me want a camaro again :p

wow ColinL, you are all over the place, Bimmers, Bikes, Scooby, and now domestic muscle:lol:

So even a bored and stroked 350 to a 383 is small block?

Ron

ColinL the 5.0 started life out as the 289 not the 302. What role does deck hieght play in this?