Longblock? Shortblock?

[Beyond Imagination]

What's the difference between longblock and shortblock?
Thanks ...

[Someguy]

A short block is the block, crank, rods, pistons, and rings; IE, the "bottom end". A long block is a complete motor including heads, cams, ect.

[fritz_269]

Originally posted by Someguy
A short block is the block, crank, rods, pistons, and rings; IE, the "bottom end". A long block is a complete motor including heads, cams, ect.

And a "turn-key" or "complete" motor includes all the stuff like the intake manifold, throttle body, headers, alternator, etc.

[drift]

i thought a longblock is a large motor, and a shortblock is a small motor

[fritz_269]

Originally posted by drift
i thought a longblock is a large motor, and a shortblock is a small motor

You almost got me.

[integr8]

Then whats a bigblock? You always hear about old chevy bigblocks and stuff and Im foreign to muscle car talk. Is a bigblock like a complete chevy engine including duplicates of all the parts stacked on top for WHEN they go and you HAVE to replace them?

[Beyond Imagination]

So a longblock doesn't include the manifold, throttle body, headers, alternator .. etc???

[G-Forces]

That makes no sense. Then why don't they call it a full-block and a half-block?

It's funny how these terms come about sometimes.

[drift]

Originally posted by integr8
Then whats a bigblock? You always hear about old chevy bigblocks and stuff and Im foreign to muscle car talk. Is a bigblock like a complete chevy engine including duplicates of all the parts stacked on top for WHEN they go and you HAVE to replace them?

big block is a term from muscle cars... for instace, with GM, they had 400ci and larger blocks all based on one block. this was their "big block" lineup. on the other side were the small blocks, aka mouse motors, which are based on the 350 block.

[Someguy]

And just to make it confusing you can take a Ford 351 Windsor small block, punk and stroke it out to a 427 which would make it a small block bigger then a 390 big block.


Also it depends on who you buy it from how complete a long block is. Some companies sell "long blocks" which would qualify as what Fritz describes as a "complete" or "turn-key."

[fritz_269]

The Chevy small block is a specific iron casting and minor variations thereof that has been produced since 1955. It's been produced in displacements from 262 ci to 400 ci. The Chevy big block is a different casting, and has been around from 1965 and has been produced in displacements from 366 ci to 502 ci.

The cool thing is, that since they're all nearly the same block, any part from any small block engine can be swapped from any other small block engine. i.e. You can use any cam made since 1955! This means that not only are there thousands of options, but they're really cheap since there are so many. Same goes for the big blocks.

Ford did the same thing as Chevy. The Ford big block casting (1968) went from 370 to 460 cid, and the Ford small block casting (1962) ranged from 221 to 351 cid.


Drift is right about "complete" v. "longblock" motors - some sellers put everything on a longblock - make sure you know exactly what is and is not included before you buy! In my experience though (mainly with domestic engines) a longblock is generally just the shortblock + heads, valvetrain, and sometimes an oil pan.

[Someguy]

Well, the 351 is a little different casting then the 302/289 ect. It has a taller deck height, but all the heads, cams, ect are interchangable, besides the lower intake manifold, but that's pretty close.

[fritz_269]

Originally posted by Someguy
Well, the 351 is a little different casting then the 302/289 ect. It has a taller deck height, but all the heads, cams, ect are interchangable, besides the lower intake manifold, but that's pretty close.

Right, same thing with the Chevy's - there have been something like 50 different casting numbers over the last 47 years for the small block - but each shares a massive amount in common with all the others. Mostly the differences are just the different bores sizes and incremental changes, things like moved bolt holes and revised seals or cooling or oil passages.

It's still amazing to me that I can pull a crankshaft from a 1955 chevy pickup truck and put it right into a brand new, 2002 Corvette LS6 engine. The only thing I'd have to add is a rear main seal adapter (which GM themselves sell for about $70) as they slightly changed the rear seal configuration in 1986. Everything else would fit perfectly. Kind of freaks me out.

[Moppie]

Just think of all the Millions of $ GM has saved since 1955 on engine development.
Also think about how unsafisticated the new LS6 is, especialy when compared with V8s from other Manufactors.
(and dont tell the Corvette owner that the only thing seperating his expensive and very powerfull engine from a 50s pick up are two cylinder heads designed by a small Britsh Enginering shop and occasional car maker. )

[Someguy]

They shored up the bottom end a bit over the years, but hey. If it works... My boss averages 24 mph city driving in his Corvette. Not too bad for 345 hp.

BTW Fritz, thinking of simple yet effective designs, my car just got back from the shop after its little surgery.