[jimmy daniel]

I have a 400 YZ block but it does not say 400 on the side of it and doesn't have the VIN number. Has anybody ever run into this before and what does it mean. The code is right and the dates are right.

[johnta1]

What date code?
What block casting code?

[jimmy daniel]

John, I've already sent it to the machine shop so I'll have to find out. The date was C149. It had the usual set of number on the upper left of front of block with the YZ stamped under that but when I looked in the lower part where you will usually have something like 29B###### (last 6 of vin), it's blank.

[robz]

Fremont Plant stamped VIN up near passenger head..

[Uncle Judge]

Originally Posted by jimmy daniel

I have a 400 YZ block but it does not say 400 on the side of it and doesn't have the VIN number. Has anybody ever run into this before and what does it mean. The code is right and the dates are right.

Do not forget that the different plants stamped blocks in different areas and different font sizes. Pontiac of course stamped their blocks fairly deep, vertically, using a large sized font located near the timing chain cover. Other plants IE Freemont, stamped their blocks much higher, near the passenger side head on an angle. Their font was also much smaller and lightly stamped. You really have to examine the block face closely and in all areas of the passenger side to confirm for sure that it was not stamped. As with any of these components, It is certainly possible to have a block that was not stamped.

[jimmy daniel]

I thought pretty much all pontiac blocks said 400, 428 or 455 etc.. on the side? This one doesn't.

[70ra455]

You mean "cast" numbers not stamped? I don't believe (but I could be wrong) that the 400 blocks had the casting whereas the 421 and higher did?

Anyway I thought I'd throw that out there. But TJH and/or HELDFORANSOM will weigh in and get you closer to the truth (as well as a bunch of other guys here.)

[jimmy daniel]

Yes. Mine is missing the casting number AND is only stamped on the front below the left head.....7 numbers and under them, YZ. I looked all over the front of the block for the other numbers that usually have the vin included and couldn't find them.

[engineer]

casting ci values was not done for all displacements.

[Wick]

I ran a SR 428 for years street racing because it did not have "428" on it plus we ran a 455 crank. Told everyone is was a 350. It did have SR on the front but no VIN stamping anywhere as well. The only numbers on the block were the date, SR and a few numbers under the SR.

[RAM AIR 1967]

My 72 455 HO GTO has no VIN stamping on its block.

[Tellyshavilli]

I have had more than a few 1968 and 1969 400 blocks without any vin. stamped on it , they just forgot .

[jimmy daniel]

What about "numbers matching" situations. My block has the correct YZ and the correct date soooooooooo, mine would be considered numbers matching? My block heads and intake all have the same date within about 3-4 days so I should be right?

[pmdclassics]

I have seen a ram air block that actually had the VIN stamped on it twice, one in the correct location and the second stamp just up and to the left about 2 inches from the correct location.

[johnta1]

The 400 was probably the last to have the '400' cast on the side of the blocks. Usually in 1970 I think.

I would say you could make that engine a numbers matching no problem.

They may have forgot to stamp the VIN on this engine or possibly it was a Service Replacement block.

[thepontiacman]

A lot of the early blocks(pre-70) did not have displacement raised numbers on the side of the block. Most blocks from 71-newer have the displacement on the driver side of the block.

Is there a block casting number on the area behind the passenger head?

I have had SR blocks that didn't have vin, but not a regular production block.Serial numbers are stamped in different locations as stated above in another post.
I would inspect the front surface real close and make sure the vin is not there. Sometimes it is faintly stamped.

Another explanation may be that it may be surfaced & restamped.

thepontiacman1@aol.com

[jimmy daniel]

when I get it back from the machine shop I'll check the rear too. I looked all over the front and the vin's not there.

[BLKBRD]

Guys,

I sold Jimmy the block in question, and as he stated, the block is dated C149. The part number is 9790071 and is completely cast, not partially cast-partially stamped. There is no VIN stamp anywhere on the front of the block, neither off to the side of the timing cover in the usual place, nor up at the passenger side deck as was common with the Freemont cars. The block has a EUN in the normal location with the YZ stamped beneath it. All of the alphanumerics are the correct size and font used by the factory, and all are aligned perfectly as if they were "gang stamped". There is no doubt in my mind that this is a production block that for some reason never had the VIN stamped on it. I have seen other blocks that did not have a VIN stamp, but it is a rare occurrence. The car that it came out of is an original RA III 4-spd car. From my research with previous owners, this block had been installed in the car sometime in the late 80's when the original blew. I have no reason to believe that it is a restamp, since it would have been restamped with the incorrect code (YZ instead of WS), and the date code on the block exceeds the build date of the car by nearly one month.

Jimmy,

The EUN (Engine Unit Number), the series of numbers stamped into the block just above the YZ, could be used by a knowledgeable individual to determine that this block is not original to your car. The build sheet may identify the EUN of your original block. Others members of this board would know for sure.

[jimmy daniel]

BLKBRD,
That was one heck of a crating job on that block. I'm saving it for the next time I need to ship one. I've got it all in the machine shop and should start building it late next week.
I never knew those EUN numbers meant anything. Whenever I read McCarthys book or similar stuff, I never see that number used for anything.

[dancolkate]

OK steved400, you're up at bat !!!!