[mzbk2l]

Trying to help a member on realoldspower.com who picked up a couple of Pontiac blocks. I don't have any of my Pontiac books over here, so I told him I'd post his numbers here and see if someone would ID the blocks for him.

Block #1: Date: D254 Code: Y9 (455)
Block #2: Date: H307 Code: XH (two motor mount holes per side.)

See the thread on ROP here. If someone can post any info on the blocks here, I'll reply to him on that thread.

Thanks.

[johnsma22]

Block #1: Is a 1974 250hp 455 block for auto trans for A,B,F, &G body cars. It came from the factory with 4X (1H) heads at 8:1 CR, and an 067 cam and 7044262 carb.

Block #2: Is a 1967 350hp 400 block for auto trans cars (GP I believe). It came from the factory with 670 heads at 10.5 CR, and an 066 cam and 4242S carb.

[mzbk2l]

Cool, thanks John.

[mzbk2l]

If anyone has a book handy, he's got one more block to ID:

Block #3: Date: H270 Code: YC (455)

[johnta1]

You need the block casting code on the rear of the block also.

Try my site:
Engine Search

It could be a late 1970 455 from a GTO or an early 1971 455.
The 70 had a different block casting number.

Also, there should be a partial VIN on the block down further next to where the timing cover bolts on.

[mzbk2l]

Thanks, John. I guess I was under the impression that the two digit stamped code from the front of the block, along with the date, would tell all. (I usually use Pete McCarthy's book, but I don't have it over here with me.)

I'll direct him to your site to make sure he has the correct information.

[johnta1]

Usually the date code is sufficient.
This block is close to the model year change over. (AUG 70)

So, it would be wise to see the block cast code to further ID it.