Big block ,Small block

[Drewcrane]

This question has been asked before Im sure but just what is the difference between a big block and a small block?

From any manufacturer :idea:

[1badchevelle]

cubic inches! what is it that you are asking or want to know, be bit more specific. search button seems to answer a lot of questions as well.

[EFI69Cam]

Typically what differentiates the two is the bore center of the blocks.

Its not really cubic inches as there was a 400" SBC and a 400" BBC

[ArtosDracon]

I think he meant cubic inch potential, there are no 638ci SBCs. Though with new hemi's and LS engines able to reach the 420's and 450s respectively, the difference is dwindling.

[Vicinity]

Size of the actual block.

[Vegas69]

One has a SMALL block, and the other has a BIG block. haha Sorry..

[MoparCar]

Drew,
I know you are a Mopar guy too so I understand the question. Mopar has an aftermarket 440 cube "small block" so it this truly a small block or big block......hmmm....possibly old school terms or maybe the bore is more of a question being a stock 440 big block has a larger bore than a small block. You can also stroke a 6.1 Hemi all the way to 440 cubes also. Again hmmm......

At first I thought, what kind of question is this, but then I'm thinking this is a great question for no more reason than to ponder. One thing is that normally a stroker small block large cube will always be lighter than a big block so maybe that's better?
Wes

[rsk68]

Ones heavy, the other is light, I couldnt help myself either!:fingersx:

[Drewcrane]

Ok i have heard this that GM did a small block and a big block,but as to what that really means is the block is bigger in dimensions than a smaller cubed engine,and a different casting with more weight of course ,so i guess the question is who coined the term "big block ,small block"?

,mopar did a 318 poly motor it was considered a big block compared to other engines, so i dont think chrysler used the term big block or small, i might be wrong, its just a question to ponder ,like what is a "muscle car"?,i just put it out there for discussion ,and jokes too!:spank2:

[Drewcrane]

Drew,
I know you are a Mopar guy too so I understand the question. Mopar has an aftermarket 440 cube "small block" so it this truly a small block or big block......hmmm....possibly old school terms or maybe the bore is more of a question being a stock 440 big block has a larger bore than a small block. You can also stroke a 6.1 Hemi all the way to 440 cubes also. Again hmmm......

At first I thought, what kind of question is this, but then I'm thinking this is a great question for no more reason than to ponder. One thing is that normally a stroker small block large cube will always be lighter than a big block so maybe that's better?
Wes

but in theory the more reciprocating mass will result in more torgue/hp right? with a true 440,block, crank,rods,pistons etc?

[Small Block LSX]

Question has been answered.

However, small blocks are better. Having a nice 427 LSX under the hood makes me wet.

[Vegas69]

Ones heavy, the other is light, I couldnt help myself either!:fingersx:

That ain't always true.

[ArtosDracon]

That ain't always true.

Assuming the same materials are used for both it is. Otherwise it's apples to papayas.

[ArtosDracon]

but in theory the more reciprocating mass will result in more torgue/hp right? with a true 440,block, crank,rods,pistons etc?

More torque yes, more horsepower no.

[mikedc]

I think what the poster really needs is a broader answer to this question.

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In the 1960s the Detroit brands all phased out their 1950s engines and introduced new engine families. (engine family = engines based off the same external cast-iron design. Most major bolt holes in the same places, the same accessories & transmissions & fluid pans fit, etc.) It's like an engine "platform", the factories had smaller & larger V8 platforms.



When they were originally built in the 1960s, a smallblock V8 generally ranged from 280ci up to around 350ci (at least from the factory in the earlier years). The big-blocks usually ranged from around 370s up to the 450s.



The factories kept using variations of the 1960s engine families for decades afterwards. Most of the V8s on the Detriot market were based off the 1960s stuff until the 1990s. Over time they usually tried to push them larger & larger displacements, particularly the smallblock stuff. So when you include all possible variations out there from both the factories and the aftermarket, there is now a fair amount of displacement overlap between the SBs and BBs. Lots of smallblocks that are 400+ cubic inches.

But the engine family is still more important for parts interchange reasons than the size. A 400ci smallblock usually still shares most external dimensions & parts with a 280ci version from the 1960s, and shares virtually no parts with a 400ci big-block from the same brand.

Sort of like having a laptop computer that's just as powerful as your desktop model. Your high-powered laptop is still gonna share more parts with a weaker version of that laptop than your equally-powered desktop model.


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So, what's the point of trying to make a smallblock so big when you can just use a big-block?

Well, it's weight and physical packaging. A 400ci smallblock engine is still going to have a weight & size just about like a 280ci version. The same 400 cubic inches is gonna be a lot heavier and bigger to package inside the car when it's in a big-block engine design.

But when you can make a smallblock much larger than the factory originally designed it, then imagine what you can do with a big-block . . . the aftermarket has pushed the 1960s big-block designs up to 500-600 inches these days.


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[Taylor1969]

http://image.popularhotrodding.com/f/9063385/0702phr_13_z_+big_block_vs_small_block+.jpg

[MonzaRacer]

In general terms what most companies classify as a "big block" was the truck engines, which eventually got "borrowed" and built. Performance parts developed and since it would bolt to most readily available transmissions from most makers. So we get "big block" cars with truck engines and lots of torque.
Small blocks are generally "car" engines, and remember back in the day before ohv engines you had 4cyl,6cyl and flat head, and pretty much 300ci was limit and if you made 300 hp it was some exotic piece, rare exceptions did come by.
Beginning ohv passenger cars had hp potential, cars were getting heavier with lots of add ons and and such so guys started mounting modded truck engines in cars to take advantage of large engine design torque production as torque is king.
and remember in the beginning days, engine compartments were cavernous so transplant is normal.
Well sine the beginning day torque is still king, horse power is a number developed AFTER you get the torque curve numbers that are then put into an equation to derive the hp numbers.
Now that we have found that we can get flow numbers into a small blocks similar to make power numbers similar to or better than big blocks without the weight restriction.
Take a look at the LSx line, the engine was co developed with input form Jim Yates, NASCAR/NHRA engine builder and based its design around stiffness, air flow and reliability.
Now for a push rod engine with one thought in mind, of power production its pretty close to near perfect.
Ford now has the Mod motor, which in design respects was developed with the ability to make 2cyl(yes), 4 cyl, 6cyl(see 2011 Mustang), 8cyl, 10cyl and 12 cyl (when Ford still had a bigger stake in Rolls Royce and Jaguar)Now they also were thinking of 2, 3, 4, and even 5 and 6 valve configurations with single and double over head cam configuration.
Fords ohc idea was/is an offshoot of SVT,SHO(yes they had a section with that title before SVT, Ford Motorsport, and Ford of Europe involvement with Cosworth)designs to get push rods out of the way of ports.
Now take both LSX and Mod, both built around air flow/quality both can be made to produce large power numbers in small packages.
Now still you drive up in a 70 Chevelle with a 3 deuce or 2x4bbl 427 Corvette engine or 8 stack injection intake or some other setup and say maybe a prot NOS kit, more guys are going to ooh and ahhhh rather than if you show up with a LSx.
The guys who know that both can run with each other if built right are swayed by both, high tech guys will lean next to the LSx, old school guys will lean towards a big block.
for the record the GM iterations small block is 1in shorter, 1in narrower and 1in in length less than a GM big block. Weight considerations are a big block with aluminum heads/intake weighs the same as small block, yet both can be had in all aluminum, yet LSx can also be had in aluminum.
Now to put another thing out there the Ford Mod motor is TINY EXCEPT for the top end making packaging hard.
This is one reason why the LSx is ohv. Now add in it can have variable cam timing, be nearly 500 cubes and make big power.
But you have to think the SBC lasted nearly 50 years before a new engine design was needed.
Pretty cool, just wonder how long the LSx will live?

[Drewcrane]

So really the term big block , small block was coined by GM years ago,

i really havent seen it used in any mopars books that i know of,the mopar engines ,small block was an LA engine 318,340,360

,383,is an R block,and 440 is a RB block,the difference from these two is the 440 has a higher deck height, bottom casting is the same , except for the internals,

it seems people have just used the name for description,kinda like "posi traction" on a mopar its "sure grip", people just use the name for ease of describing the engines,thanks for all the input here it will solve alot of arguments on this subject i hope:spank2:

[mikedc]

No, it's really not a GM-centric designation. Ford and Mopar both have clearly understood "small block" and "big block" motors.


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When we describe all this stuff in text, the different engine details might kinda jumble up and run together in the reader's mind. But if you actually had all these motors in front of you, the SB and BB differences would be very clear.


For example, the Mopars - yes, there were multiple deck heights on the "big block" shape. The B and the RB blocks.

But if you had half a dozen different 1960s Mopar engines all sitting in front of you, there is absolutely no question of what is related to what. The B and RB blocks are both rooted in the same design. Even with different deck heights, they are so similar they can barely even be told apart just by sight. Almost everything (including the actual cylinder heads) is still interchangeable between them.

Whereas you can pick out a B/RB block from any LA (small block) from across the room.

---------------------------------


Let me put it this way - I could rattle off a ton of differences between the Camaro and Firebird. When it's printed in text and you don't have any visuals to work with, the descriptions could easily start to make the these two cars sound like very different animals from each other. Same with the differences between a Chevelle and a Pontiac GTO.

But they're not. Park a 1969 Camaro, a '69 Firebird, 69 Chevelle, and a 69 GTO all together . . . there's absolutely no question which two are related to which other two. You can clearly see it from across the parking lot, no matter how many differences can be documented on paper.


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[Drewcrane]

No, it's really not a GM-centric designation. Ford and Mopar both have clearly understood "small block" and "big block" motors.


--------------------------------


When we describe all this stuff in text, the different engine details might kinda jumble up and run together in the reader's mind. But if you actually had all these motors in front of you, the SB and BB differences would be very clear.


For example, the Mopars - yes, there were multiple deck heights on the "big block" shape. The B and the RB blocks.

But if you had half a dozen different 1960s Mopar engines all sitting in front of you, there is absolutely no question of what is related to what. The B and RB blocks are both rooted in the same design. Even with different deck heights, they are so similar they can barely even be told apart just by sight. Almost everything (including the actual cylinder heads) is still interchangeable between them.

Whereas you can pick out a B/RB block from any LA (small block) from across the room.

---------------------------------


Let me put it this way - I could rattle off a ton of differences between the Camaro and Firebird. When it's printed in text and you don't have any visuals to work with, the descriptions could easily start to make the these two cars sound like very different animals from each other. Same with the differences between a Chevelle and a Pontiac GTO.

But they're not. Park a 1969 Camaro, a '69 Firebird, 69 Chevelle, and a 69 GTO all together . . . there's absolutely no question which two are related to which other two. You can clearly see it from across the parking lot, no matter how many differences can be documented on paper.


-

yea that makes sense too! i can spot an R engine over an RB engine block there are some tell tale things , but you are right a small block is a different looking block,not just the size and weight, distributor location,water pump etc., 383 ,440 there about the same except like i said with different internals, and the 440 has a flat boss on the front of the block under the intake,as well as the higher deck,


and as i posted before AMC used the same blocks,interesting comments:cheers: here

[LeighP]

When talking GM and the "small and big block" thing....please do not lump PONTIAC under that GM umbrella.
PONTIAC traditional V8s are neither small or big blocks. All PONTIAC V8 engines share the same external dimentions (except the 301 which is a short deck block).

[DocJr]

Interesting things to remember: 1960's "Experimental Engines"

Olds had an all aluminum 455 DOHC Hemi that would have killed "Chrysler's 426" which later became the Aurora V8 (and Indy version).

Now sure, don't get your panties in a bundle over my sly comment above, we may never know everything that was under Chrysler's sleeve...or anyone else's sleeve for that matter! HAHA All in fun guys!:jump:

but yea, back to question at hand....I think everyone's just taking their best stab at this question, I for one never understood the concept, I don't really care either.."is that a small or big block?" Who cares?? its got a lot of power!!

[MonzaRacer]

Well now on Pontiacs part they could be considered a big block, but manufacturer wise they never needed a second engine, the Indian is already a torque engine, just very few in 50s-60s-70s paid attention.
My machinist was winding a 400 Pontiac ,with arma cast rods, over 8500rpm in stick car. I have the hard chrome crank and old school Echlin dual point dist too.
Pontiacs can be built to make well over 500lb ft of torque and never exceed 5500 rpm, Caddy was the same way. They built torque engines to pull heavy cars.
Buick and Olds did similar things, now GM got funky with the 215 sharing bottoms ends, being aluminum, etc. That stuff came over from Europe but never caught on big, what you want in your Camaro,Firebird,etc? 215 v8 all aluminum or a 302/396/427/454 or 389/400/428/455?
Remember Vega engine fiasco(ie you need new sleeves your aluminum cylinders are worn out sir) Same tech came from 215 program, just aborted for the V8 cause aluminum is too soft, cylinders ovaled out in few minutes.
Olds differentiated by cubes, ie 350 was "small block" 455 was "big block" and while share architecture they dont share many if any parts, Buick did similar ideas. And Caddy , well they just built big torque engines to pull fancy land barges (but then the 02 RSE Caddy Schwartz Perf built was awesome, pattern for my Caprice).
Now GM ,well Chevy tried to build a big block in 50s, 348/409, but had limited yet memorable success.
Now ford just made new designs, Y block in 50s, then the Windsor block from 221ci through 351, racing brought out a second Y block in the FE engine which gave us the infamous 427 side oiler and it kissin cousin the SOHC 427, Racing also gave us 351 Cleveland which did shar some architecture with Windsors(remember Boss 302/351) many a then donated heads/intake to be adapted to Windsor , the Modified engines came from emissions strangled Clevelands, and the venerable Boss 429 and of course the venerable Lima engine in 429/460, with few *******s in mix.
AMC never had BIG trucks so no, thay never had big block or small block, and AMC always had cool cars yet was a scrape together company till absorbed by Chryco.
In todays world if you can build it to make torque, ie air flow its gonna run good.

[ArtosDracon]

I've always wanted something with one of Caddy's big blocks, I mean a factory direct 500? Hell yeah! 4.3" bore, 4.3" stroke and 550lb/ft of torque, gotta love it. It's too bad they weigh almost as much as my truck.

[Drewcrane]

When talking GM and the "small and big block" thing....please do not lump PONTIAC under that GM umbrella.
PONTIAC traditional V8s are neither small or big blocks. All PONTIAC V8 engines share the same external dimentions (except the 301 which is a short deck block).

aah haa see im a Mopar guy and dont know about GM,very much,(one of the reasons i posted this thread), but now that you mention that i guess i have heard that ,and buick motors are different too right?,so Pontiacs are like AMC,S wit the same outer dimensions on most of there engines:cheers:

[thumperamx]

aah haa see im a Mopar guy and dont know about GM,very much,(one of the reasons i posted this thread), but now that you mention that i guess i have heard that ,and buick motors are different too right?,so Pontiacs are like AMC,S wit the same outer dimensions on most of there engines:cheers:


AMC ..... YES & NO
The early AMC 287 & 327 engines were small cube eingines but , they had a larger physical size then the Later series , they are a small block . These early engines looked simular to the Ford Y-Blocks (272, 292 & 312) .
The 290 thru 401 series all shared the same engine design and outside demensions are the same , also many parts interchanged . This series is a Small Block also , even the 390 & 401 and NO , AMC did not use a Ford 390 . The AMC 390 & 401 used the same bore , the 401 had a longer stroke . The 390 & 401's weighed 35 or so pounds more due to the cranks , rods and heavier webbing in the block , the Special 360 Block also had heavier webbing . The 290 , 304 , 343 & 360's had a smaller rod journal than the 390 & 401 , all used the same main journal size . The block deck height was raised in 1970 . This engine series ran from 1966 untill the end of AMC's production , full size Wagoneer V8 .

[79-TA]

but in theory the more reciprocating mass will result in more torgue/hp right? with a true 440,block, crank,rods,pistons etc?

More mass to move means more energy is required just to keep the engine components in motion. That means less power to the flywheel and ultimately, the wheels.

Torque is a result of the force being applied on the pistons from the combustion process. A heavier rotating assembly will have more momentum and will be less susceptible to losing rpm and bogging under a sudden load, but no extra peak torque will be created just by having a heavy rotating assembly. The extra mass will actually take extra force to accelerate and move at the same rate.

A heavy rotating assembly is only desirable for durability and perhaps hard drag racing launches.

Big blocks are about cubic inches, not mass . . . though they certainly are massive. The more volume the engine has, the more vacuum it can produce at whatever given rpm which lets it suck in more air which lets it burn more fuel which lets it make more power.