Small Block and Big Blocks

Home  \  Domestic Cars  \  Small Block and Big Blocks

What's the difference between the two, and what is the difference between short block and big blocks or are they just other names for small block and big blocks. I looked through some sites but I think the answer to my question may be better answered on here. Thanks

posted by  Pythias

hang on, there's a thread we discussed this in....

here's long block vs. short block...
http://www.car-forums.com/talk/showthread.php?t=12357&highlight=block

here's some discussion on small block/big block...
http://www.car-forums.com/talk/showthread.php?t=12827&highlight=block

enjoy... :thumbs:

ps: the search button is your friend...

posted by  dodger65

I've already covered this a few times. Of course if you revive an old thread about it it'll be locked, so here's the short version.

Longblock/shortblock. Very basically a longblock is a complete engine assembly, not including the intake manifold, oil pan or any accesories. A shortblock is a longblock without the cylinder heads installed.

Big block/small block. Refers to the architecture of the engine, bore spacing normally being the primary determining factor. For example a small block Ford has 4.380" bore spacing but a big block Ford has 4.630" (FE engines) or 4.900" bore spacing.

posted by  vwhobo

Thank you, could you possibly link me to the threads, I was also wondering about the advantages and disadvantages such as power, I am currently searching for a thread that may answer my other questions though.

posted by  Pythias

Which are?

posted by  67Coronet383

Very generally speaking, more displacement means more power. And again very generally, big blocks are torquier and small blocks rev higher.

posted by  vwhobo

does ford really distinguish any of their motors as a big block, tho? b/c i know they have a shitload of engine series' .... small block, FE, 385, Modified :trails off:..... shit, i used to know them all, too.... :doh:

posted by  dodger65

Which are even though more displacement means more power at what cost? They are also heavier no doubt and how does that play in? Is one more reliable than the other? What are the advantages and disadvantages of each?

posted by  Pythias

depends on the brand of motor... which brand are you wondering about?

posted by  dodger65

I was really just wondering in general, and how the LS7 was considered a small block because of such displacement.

posted by  Pythias

mostly b/c they consider it yet another evolutionary change in what is now considered the small block chevy.... and (i think) to inspire a sense of nostalgia in us all... :warm fuzzy:

i don't even know why they call it a small block. there aren't any new (production) chevy big blocks being made, so they don't need to distinguish between them (an "only-block" chevy v8?) and the design is so far removed from the original 265 small block that it's not even pertinent anymore...

posted by  dodger65

I see, thanks for the info.

posted by  Pythias

You can still purchase a GM big block through the GM Performance Division, so there is still the need to distinguish between them. The LS7 is considered a small block because it has the same size block as... the original small block. Which is how the big block/small block classification came to exist in the first place.

posted by  Bino

i said production big block, as in still being factory installed in new vehicles.... my point is.... if i say i have an ls7, do you know what i am talking about?exactly... and do you have any technical specs to verify the sameness you speak of? (i'm not trying to be a dick here, i'd just like to see them for my own knowledge)

posted by  dodger65

EDIT: looking at a couple of articles here, we're both right in a way

http://www.idavette.net/hib/ls1c.html

apparently, the only similarity betw/ the ls motors and the original small block is the bore centers....

more ls7 stuff...

http://superchevy.com/technical/engines_drivetrain/completebuilds_testing/0 504sc_ls7/

posted by  dodger65

Hence the reason that bore centers are the primary determining factor between small and big blocks. Another thing that people wrongly believe is that displacement is the determining factor. For example the new LS7 is a small block and has a displacement of 427 cubic inches but Chevy built for years (and maybe still does) a big block of 366 cubic inches. And we all know about the 396 big block which is smaller (displacement wise) than the 400 small block.

posted by  vwhobo

fine... point taken... how 'bout those 350 & 360 chrysler motors, huh? don't forget them...

posted by  dodger65

Chevy is most assuredly still producing a big block for production vehicles... Not cars, but current year production vehicles none the less. What do you think pushes around most Ryder, U-Haul, etc big trucks. You got it, an 8.1 liter, gas V8, big block.

http://www.chevrolet.com/i/pic/mediumduty/kodiak/c7500_home.jpg

posted by  vwhobo

i was under the impression that most were diesels...

ok, fine! they can call it a big block then... :wink2:

posted by  dodger65

The small block/big block differnce generally was a Chevy thing. Fords used a lot of different engine types, and Chrysler used letter designations for the different engine families.

On the chevies, another engine family trait is teh valve layout. Generally, the factory small blocks used inline valves on a wedge head, while the big blocks used canted valves.

Small block head:

http://www.strokerkits.com/215RR-int2.jpg

Big block head:

http://www.strokerkits.com/BBC-right-angle.jpg

posted by  ChrisV

Wow. This subject raises a lot of generalities none of which answer the real question. I've never given it much thought, as it's not all that important seeing as it just groups up engines into a small or big block family. However, I've always noted that it seems to have to do with out ward physical size. Just another generality to add to the pot. A big block is a big block, and a small block is a small block. An apple is an apple and a peace is a peace.

posted by  67Coronet383

A peace is a peace? What is a peace?

posted by  Pythias

Generalities? Somehow using the words archetecture and especially bore spacing seems fairly specific to me.

posted by  vwhobo

Of course. What I'm saying is there is no universal statement to be applied here. No one can say "small blocks can be identified by...and big blocks can be identified by...." All I'm saying is there is no one sure way to distinguish between the two. So far everyone has just said a lot of small blocks and big blocks have this in common, which is a generality and not a specific way to determine which is which, and why a small block is called a small block and a big block a big block. For the mopar part of this deal you have their small block family and big block family. 350(RB)-440CID in the big blocks. Small blocks you have 273 - 360CID. WITHIN each family (SB & BB) they are basically the same engines but with different bore and stroke measurements. When you look at a small block and a big block, their most obvious notable difference is ******d physical size. FOr this matter, I'm saying this is the reason they call their big blocks big blocks and their small blocks small blocks. Makes sense to me. One group of engines (basically the same, just different bore X stroke measurements) has the smaller block, and the other group has the bigger block. Makes sense to me. This isn't always the case, as it's the same with every other response to the question of what makes a BB a BB and a SB a SB. SO like I said, generalities such as what I just stated don't really answer the question, and there is no universal statement to distinguish the two. Therefor a SB is a SB and a BB is a BB. Peaches are peaches, apples are apples (Peaches is what I meant in my last post...not peaces.)

posted by  67Coronet383

Okay, I understand what you're getting at. One reason that I explained it the way I did, besides being the correct answer, is the fact that most of the people on this forum have and probably never will see an engine block outside of an engine bay stripped of accessories. To them, most any V8 looks big enough to be be a big block. Couple that with the fact that the critical dimensions vary among manufacturers and it is somewhat of an ambiguous description.

On the other hand, how many people know what is meant by bore, stroke, bore spacing or maybe even architecture?

posted by  vwhobo

Okay.




I wouldn't know.

PS I wonder why ******d (out ward) is filtered. :banghead:

posted by  67Coronet383

Well when I was a boy, the general guide was small blocks up to 6 litres, with a couple of oddball 6.6 litre chevs thrown in. 6 litres and over were generally considered big blocks.

posted by  Wally

i have no idea what you are talking about w/ all this bore/stroke buisiness... :wink2:

posted by  dodger65

I have a 6.2L(6.27L) small block chev:)

posted by  BanffAutoSpa_ap

http://www.hotrod.com/techarticles/engine/113_0307_454/

posted by  67Coronet383

Your Message