Hello,

I don't know much about cars. I am curious. What is the difference specifically between a small block vs. a big block? Is it simply just size? Thanks

 

Chevrolet has 2 basic V8 engine platforms. Smallblock is 262, 265, 283, 302, 305, 307, 327, 350,(383 also) and 400 cubic inches. The block is externally the same size for all of these. Big block car is 396, 402, 427, 454 and then 502. All these blocks are the same external dimensions. (There is also a tall deck big block truck that is 366, 427, or 454 c.i.d. that is similar to the car big block, but has another ring)

 

So the basic size and block are the same for all these, right? So is the only difference in these engine sizes the cylinder and piston size?

This has always been my assumption, but since I saw this post I figured I'd ask.

 

The small blocks use one size block as the prior poster indicated. Variations of bore and stroke giving the displacement.

Big blocks use an entirely different block. As with the small block, variations in bore and stroke give you the displacement.

Heads and intake are different for a small block vs a big block.

Big blocks are heavier, take up more space than small blocks but give you more torque. Engine compartment gets rather tight.

 

In simple terms, the iron block bigblock has larger external dimensions than the iron block smallblock and weighs well over 100 lbs. more. This can vary, of course, depending on use of any aluminum bolt on parts on either. Bigblocks use different pulleys and brackets for accessories and the extra overall weight requires higher rate front springs.

 

Big blocks have bigger fatter valve covers. That's the only way I can tell by looking at em. In general, on average, big blocks are bigger than smallblocks, but there is a 396 ci bigblock and a 400 ci smallblock, and with the new engines, the ZO6 has a 427 ci smallblock.

 

Well the Z06 is a Gen 4 small block so it is a totally different beast. But there are people making 454 Gen 1 small blocks with aftermarket blocks. You can also do a 598 big block with an aftermarket block.

 

LS engines are LS engines, not small blocks. They don't share anything. Different architecture, valve angles, block design, yada yada.
You can do a lot larger than 598 with an aftermarket big block, they're at 900 or so now and still climbing.

 

Big block heads can flow LOTS of air, even with a pretty bad casting.

You can put ported smog heads on a smog-era Ford 460, swap in a cam and have 450rwhp, easy. Probably could pick the truck up for $2k and be all in with the motor for $3k. Then start breaking the rest of the truck with the newfound power.

Same goes for Chevies, but I got a good deal on a Ford truck so I know a hair more about Ford big blocks.

 

Size DOES matter!

 

You can make some power with a small block, I have made some exhaust changes ( bigger headers and removed baffles I had right in the pipes to quiet it down ) and will be shooting for 500 RWHP N/A the next time I take it to the chassis dyno.

Now here's the important thing to remember. After about 500HP or so with a small block the dollar per HP goes up exponentially meaning you can go from 400 to 500hp for very little but it starts to get real expensive once you try and hit or pass the 600HP mark. At that point it is probably better, easier and even cheaper to go with a big block

 

dart is making some good blocks... like the little M i hear many good things

 

Its easy to spot the BB Vette owner as hes the guy with the big grin on his face........

 

I think Mark has you covered.
262 ci is a new one for me...never heard of that before, but I don't doubt that it's out there.

Some more basic fun facts. The small block design came out in 1955. The displacement was 265 cubic inches for 1955 and 1956. There were no oil filter housing cast into the block in 1955 so these engines are pretty easy to identify. 1956 was the first year with integrated oil filters. The 283 ci engine came out in 1957 and displacement progressed from there. The Chevrolet small block design is generally considered the most successful V8 design of all time (however this is debatable, as with everything...)

The big block design is larger in physical size but they look similar to the average person. The valve covers give it away for me, they are just a lot wider and have lots more fasteners to hold them down. Each design has their strong and weak points so you will love or hate either type.

There is a third style of engine out there called the W blocks. These would be the 348 or 409 engines from the early 1960's. The only real way to tell the difference between the two (besides casting numbers) is with the placement of the oil dipstick tube. (Driver or Passenger side). These engines aren't too popular for the average hot rodder because they cost a bit more than the other two and are harder to find. They look very distinctive and could never be confused with the big or small block models. The 348s are plentiful in old pickups from the same era, the 409s are practically gold these days.

I have a 265 in my '55 Bel Air and haven't yet driven it. (still restoring...)
I have a basic L48 small block in my '76 Corvette and a 348 in my '61 Bel Air. The 348 is very strong at low rpm like a big block but is slow to rev. The L48 in the '76 seems like a good all around engine. It runs well, starts easy and doesn't overheat. It's a bit shy on power but I've sorta outgrown the stop light to stoplight thing anyway so I just enjoy driving these cars nowadays. The 327 and 350 engines from the late '60s and very early 70's have a lot more power than my '76 does so the build year does make a difference. Most people will agree that the best bang for the buck is a properly built 383 which is not really a displacement that GM ever offered (at least not that I am aware of). The 383 is sorta a hot rodder's brew and has proved quite powerful for not too much money.

Are you shopping?

 

And his credit card always sitting on the console ready for the next gas stop. Not that I have any personal experience with that.

 

LS engines are small blocks. They are the Gen III (ls1, ls6) and Gen IV (ls2, ls3, ls7, ls9) small blocks. But yes they are a completly different design than the earlier motors. Also the LT1/4 motors were the gen II small blocks. They mainly differend in the reverse flow cooling system and optispark.

Small block and big block are just the way of differentiating between the different sizes of castings. The small block wasn't considered a small block untill the big block came out. The big block was just a bigger casting than the small block.

As mentioned above, the valve covers are an easy way to tell the difference between a small block and big block. Also, at least with chevy motors, the big block has equally spaced exhuast ports and exhaust manifold runners(O O O O). The small block has the middle two ports/runners closer together(O OO O).

 

Great description! I would have never thought of trying to show the spacing like that but it makes perfect sense. (I wonder if there is a symbol that can be used for tunnel port....)

 

Well, if you're going to call LS engines smallblocks, this won't work any more, LS's have the same exhaust port pattern as big blocks

IMHO, it doesn't matter what GM calls 'em, Gen Whatever, mechanics and hobbyists knows 'em as LS engines, NOT smallblocks.

"Mr. Engine Builder, I want you to build me a nasty 427 smallblock"
"OK, do you know what parts you'd like used - crank, heads, etc.?"
"Yeah, I want some of the factory CNC ported heads and a production LS block"
"Oh, you want an LS engine. Why didn't you say so???"

 

The cubic inch of an engine is not related to Big block or small block. It referes to the bore spacing which changes the outside size and within the engine world the terms are related to thier engine families as to which is a big block or small block. As to chevies I believe the list that has been posted by others is pretty good as far as what c.i. engines were called what.

 

Plenty of people refer to them as the third/fourth gen small block. They also existed the same time as the 496/Vortec 8100. They are a small block. I doubt an engine builder would get that confused - he should realize the same thing.