March 2022 ToTM

[special-K]

Originally Posted by 3757chevy

Bill said it in the OP "This not only includes our loveable Chevy big block, but those by Caddy, Olds, Buick, and Pontiac.!" But you make a point about other GM being Small displacement BIG blocks. I'm waiting for an Olds powered square body Or a Buick powered ?

Ok, I see that now. Sorry and don't let this bungle up the contest. If Bill allowed for "BOP Blocks" then that's how it is in this contest. I guess this includes the 292, since those truly are big block straight 6s, even though you don't hear them referred to that way.

It is an age old discussion, or argument, that there is only one big block in the GM family. You have to have a small block to compare to in order to have a big block.

I love Pontiacs and would love to put one in my '67 GMC. But the 326 uses the same block as the 455. I'd want people to think my '67 had a 389 but would likely wind up with a more common displacement dressed to appear as one.

[sick472]

Originally Posted by special-K

...But the 326 uses the same block as the 455. I'd want people to think my '67 had a 389 but would likely wind up with a more common displacement dressed to appear as one.

Spot on Special-K,

Should you go with a Pontiac in your GMC...the 400 block is the most available AND is the most popular to stroke. Modern forged crank designs allow for that 400 to be reliably stroked to tremendous cubes while keeping the smaller crank journals (compared to the larger journals of the 455)...this equals an engine with high output, modern crank strength, and higher available RPM's. This approach (stroked or not) can look almost exactly like a 389, excepting casting numbers.

It's a very common thought that Pontiacs are big blocks since the 455 "sounds" like a big block and the 389 & 400 are the same block casting. The 326 usually falsely carries the small block stigma, but, as mentioned, is the same casting too. The kicker is that they are all designed more like a big block for durability when compared to other GM small blocks of similar bore and stroke. I believe there are differences between the 326, 389, 400, 421, 428, & 455 blocks. They are the same external dimensions, but the inner wall casting thickness can vary from size to size depending on the cylinder bore.

I'm not picking sides here, just glad to throw some Pontiac info out and glad to join a ToTM!

[3757chevy]

Originally Posted by special-K

Ok, I see that now. Sorry and don't let this bungle up the contest. If Bill allowed for "BOP Blocks" then that's how it is in this contest. I guess this includes the 292, since those truly are big block straight 6s, even though you don't hear them referred to that way.

Well ...just for sake of argument how about the straight eight , that's big . JK

[D.B]

Here is my 72 C20 with a 511cid Gen V big block.