Hi everyone,
I am new to this forum so please forgive me if I am asking a question that has been answered 100 time before.

I have a '68 442 convertible with the 400cid engine , 325hp (automatic car). Would my engine be considered a big block or small block? The engine is bronze with the orange air cleaner.

Thanks all!

Phil

 

Big block olds aka BBO

 

330,350,403, sbo. 400,425, 455, bbo. 303-394, no idea, lol.
Welcome to CO.

 

Welcome Phil, post a few pics of your car and engine when you get a chance.
X3 you have a BBO, how is it running?

 

Yes, it's a 400 big block. However, some will tell you that the 68-69 G block is garbage. The 64- 67 E block is closer to a square bore/stroke ratio, but a G can run fine on the street.

 

Olds has an incredibly easy way to identify engines and big vs small block. The heads have a cast numeral/letter to the lower left of the valve cover, and the block has a casting number of some seven or so digits followed by a large numeral/letter.

If it has letters, it's a Big Block Olds. If it has numbers, it's a Small Block Olds.

Your car, being a 68 442, will have C heads and G Block, meaning the third in the series of heads (after A and B) and a G block 400. You will have the big valve C heads with your 442 engine (since it's a performance car) and your G block, while noted above won't rev quite as high, but will have good ***** on the street.

 

Of course you are aware that some racers and go fast guys are using BBO heads on a SBO and others have used SBO heads on a BBO. So.....your suggestion will work on stock engines but not always on modified engines.

 

Plus some SBOs like the 72 350 had numbers and letters i.e. 7a heads

 

Welcome. Yes, this has been discussed hundreds of times.

First, there is no "official" definition of big block or small block. In Chevyland, the SBC and BBC are completely different engine families with few interchangeable parts (though I must take this opportunity to ridicule Bruce Springsteen who sings about his "69 Chevy with a 396, fuelie heads, and a Hurst on the floor..." ).

The 1964-1990 Olds motors are actually all of a common architecture - common bore spacing, common crank-to-cam centerline, common motor mounts, common front cover and accessories, etc, etc. This is why BBO and SBO take the same cams and valvetrain, and why people who build DX blocks often use 425 cranks. The only fundamental external difference between the BBO and SBO is the deck height. SBO is 9.33", BBO is 10.63". We in Olds-land have arbitrarily defined the short deck motors to be "small blocks" and the tall deck to be "big blocks", but the reality is that the relationship is more like that of the Chrysler B-block (383) and RB-block (440) motors.

As for the first-gen Olds V8s, there are really THREE different deck heights over the years.

 

It's not really a suggestion, more of how it was done. Obviously, it won't work on modified engines, or LS transplants, or Fords....

 

Agreed. But your suggested discerning filter doesn't work on later engines either like that 403s & 307s where the small block heads all have a number followed by a letter.

 

The point is that the number is the primary identifier on a small block head and you will not find a number on a big block head in that location.
Stop nitpicking about it.

 

Nit picking or being accurate?

 

Holy **** dude, I was just quoting the oldsfaq. Oldsmobile put a letter on the big blocks and a number on the small ones, and it generally works, especially in 1968, which is the year of the OP's car?

Is there a reason you are climbing up my posterior today?

 

How about this:

Letter: BB

Number (with or without Letter): SB


Does that make everybody happy?

- Eric

 

Not always your best source of Olds information, unfortunately...

 

Did you not see where I started the post with AGREED?


You flatter yourself by thinking that I am invading your posterior. I was completing your post so that the information was complete & accurate. Thanks for playing.

 

Mr. Padavano, are you saying our terms big block and small block for Oldsmobiles is not a construct from the factory or Oldsmobile itself? But a construct from us enthusiasts to discern the tall and short deck blocks which Oldsmobile would have been considered all the same block by Oldsmobile, as in your example Chrysler considered both the tall and short deck big blocks as one block with a different deck height?

 

I do not believe I have ever seen the expressions "small block" or "big block" in any Oldsmobile publication.

But then I don't recall ever seeing either of these terms in any Chevrolet publication either. I believe it was "V8" and "Mark IV V8."

- Eric

 

Which is why I said:

Meaning: ANYWHERE. The factories did not invent this term. It was created by enthusiasts and has no fixed definition. We really need to get over it.

 

Wasn't picking a fight, just actually interested. I wasn't sure what the real source of the terms was. Interesting though...

I know Pontiacs are all midblocks, as there is no big and small block... but funny enough, by the Oldsmobile standard of deck height, the 301 would be a short deck therefore a small block.

 

The 267 and 301 are short deck versions of the other Poncho motors, just like the 350 Olds is a short deck version of the 455 (or, technically, vice versa since the SBO came first). Again, applying "big block" and "small block" terms is meaningless unless the rest of the world agrees with your usage. As I pointed out above, the first gen Olds V8s came in THREE different deck heights, but no one used the "big" or "small" designations with any of them. It's a meaningless designation. Tall deck and short deck would be both meaningful and more accurate for the second gen Olds motors.

For example, what do you call a Chevy W-motor? Is a Ford Y-block "small" or "big"? What about the FE, 385, and MEL families?

 

As a total digression, I'm not a F_rd guy, but didn't F_rd make something like five different OHV "blocks" in the '50s - '70s time frame?

After the iconic flathead, I seem to recall the Y-Block, the FE [Ford/Edsel] Block, the Windsor Block, the Cleveland Block, and the Lima Block.

I guess each one was a Better Idea than the last...

- Eric

 

Which is exactly what I listed in the previous post. In approximate chronological order:

Y-block (272/292/312)
MEL (Mercury/Edsel/Lincoln)
FE (332/352/390/391/406/427/428)
Windsor/Cleveland/Modified (221/260/289/302/351/400M)
385 family (429/460)

 

Ah.

Not being a F_rd guy, I hadn't heard those other designations.

... And I'd had no idea there was a larger '50s block before the FE.

- Eric

 

Chevrolet also made a tall deck version of the BB.

 

Is that the 501cid block? Or is there yet another?

- Eric

 

427 truck block.

 

It actually started with the 366. Then came the MarkIV 427T and evolved, the deck height difference is .400" from the standard height.

 

I never knew there were that many variations in that block.

Thanks.

- Eric

 

The factory tall-deck Chevy motors were medium and heavy duty truck blocks. I ASSUME this was done to allow the use of pistons with thicker domes and thus more durability in truck applications (along with lower compression). Don't confuse aftermarket tall deck blocks (designed to accept a longer stroke) with the factory truck blocks. The passenger car and light truck BBCs all used the same deck height.

Chevy is not unique in doing this, either.

 

I want to own a Cadillac with the 500, just for bragging rights.

 

for practical purposes in today's lingo... yes your 400CI Olds is a big block

400-455 big
350 small

 

... execpt the 403.

- Eric

 

Has this now completely morphed into the ****-retentive thread?

Does that 403 have letters on the head or not?

 

big, really big and 'wtf'?