I've been prowling around the forum for quite sometime, while I restore/ rebuild/ repair a 1970 C3 coupe. Nothing fancy, but a nice driver.
My question:
I have an engine pad stamp that nobody - Yeah, I've tried the NCRS-has been able to decipher. All of the engine and realted component casting numbers match, but this stamp is driving me nuts.
If anybody can give me a clue, I'd appreciate it:
Its stamped V0705ABT, on a 300 hp 350 SBC block casting 3970010, dated May 1970, heads # 8927186 dated April 1970.
VIN 194370S411559.


Thanks

 

Are you saying the VIN derivative is stamped on the block? If not, it might not be from that car.

I do not have my references handy BUT keep in mind that most of the books we car guys have are for CARS. Info for heavy duty truck chassis or marine applications are harder to locate.

Try "1980" rather than "1970" and see what you come up with. That might be a newer block with some much older heads.

-Mark.

 

I can't find a specific ABT, but most AAx or ABx or ACx etc. codes are low HP, 2 barrel school bus or light truck applications.

Sorry.

 

I'd say this is a re-stamp...apart from the fact that ABT doesn't seem to be a known suffix code....the alpha numerics look too straight, too long across the pad, and too evenly spaced between the head and the water pump....also the font is different and the font size is too big.....

Your stamp pad should look like this:



What did the NCRS people say ? Do you have anything from previous owners that would indicate a rebuild ?

BTW, the same thing happened on my old small block....someone stamped a bunch of numbers there but they didn't mean anything....

 

Everyone,

Thanks for the replys.

There is no VIN derivitive on the pad, just V0705ABT. This is installed in a 70 vette I bought, stored in a warehouse from a guy I never met. I knew there was a numbers problem when I bought it, and the price I paid refelected that.
The storey is that the block was rebuilt, and decked. The machine shop may have restamnped the block with an ID reflecting the original engine; V for Flint, 0705 for a July 5, 1970, or 1980, or 1990 re-build date, and ABT as the initials of the machinist. This suposedly was to identify the work performed in case warranty work was later required. BUT, I have several good contacts in the automotive bussiness, and nobody can verify any of this. The protecto-plate and related warranty docs, shows the car was delivered in Miami Fl, but that was a dead-end too. No window or tank sticker.
The car runs well, everything works, and the engine is strong, so no real complaints, just a mystery stamp pad. It has a TH400 auto.
Also, the pad is just a rectangular block extending forward from the right-side head, not the longer, curved plate I see so commonly. Any one know the reason for different pad sizes? Also, I understand GM moved the VIN to the oil filter area in 1970, but I can't find anything there either. I understand it may be the wrong block - July 1970 post-dates the build date, just wondering if anyone ever heard of an ABT suffix. I have a spreadsheet, showing the build suffix, and application for just about any 350 SBC ever built, ABT just isn't there for a 3970010 cast block. The NCRS didn't have any answers either, at least several months ago. I plan to retry. I'm a member, and have the same references they do. It's old-time experince I'm lacking, and was hoping someone out there may have an idea.

 

His pad looks to be a later style where this picture is the early 70's style, that is one reason I suspect 1980 rather than 1970.

I doubt it is a restamp. Why bother if it isnt even close. I do not see a VIN derivative which leads me away from a car block and leads me to marine or some other commercial application. As I said before, the commercial chassis used passenger car blocks with suffixes that are not listed in our "matching number" type reference books. We don't have a lot of data on those applications. Heavy trucks and boats did not have the same rules about VIN stamping as light trucks and passenger vehicles.

-Mark.

 

The rectangular stamp pad first appeared on the 0010 blocks in the late 70's- IIRC, '78 maybe? This dates your block to this time period, at the very earliest. The details of the stamp pad V0705 -assuming that it's not a restamp-, means that it was assembled in Flint MI on July 5th, but does not indicate in what year. Are there traces of the original broaching marks?

Look on the rear flange of the block to get the casting date. This will narrow down probable year of assembly.

Ref, the movement of the VIN stamp, this is not correct. The VIN 'stayed put' until at least the end of C3 Corvette production.

The lack of a VIN stamp on your block might mean that is was simply an over the counter replacement engine built for the ABT application, which as I posted earlier is probably for a light truck/school bus.

 

I was told that the later 0010 blocks that were not the hi tin/nickel content had the rectangle pads as shown in the original pic. If true, then this block could be 80 not 70. It could possibly be a two bolt main also, but if it was a truck motor then most likely a four bolt.

 

1978 ABA 350 LF5 160hp 2bbl C60/ School bus
1978 ABB
1978 ABC
1978 ABD
1978 ABF C60
1978 ABH C60/ Impala
1978 ABJ C60
1978 ABK
1978 ABL
1978 ABM

No ABT from my recorces. I have a CLY that I can,t find either

 

Thanks all, for the help.

After review, consideration, and a few beers, it looks like the original block was replaced after 1978 with something from the marine or stationary engine line. The NCRS guys said basically the same thing. As all of the other casting numbers on the heads, manifolds, carb, distributor, etc are matching a 1970 vette, I assume there was a block failure, and the short-block was repaced with what-ever was available. I have 150 psi compression, and I'll check whether it's a 2 bolt or 4 bolt main, but it runs pretty good for a motor-boat engine!

 

You block is a "small pad" block that wasn't introduced until about 1978 or so. If the seller said the car was numbers matching, HE LIED!