[xaztec]

I have two blocks. One is a 2 bolt main and one is a 4 bolt main. They're both casting 3970010. Rather than try to explain all the markings, I've taken pictures of them all. I'm trying to figure out specifically what engine these blocks were used for. Thanks in advance for your help.

First the 2-bolt

[xaztec]

Here's the 4-bolt:

[xaztec]

More 4-bolt pics:

[74Ventura]

are there any numbers stamped in the deck surface? right side(passenger side)? front

[Blazin72]

The markings that you want to be looking at are the ones stamped on a small pad just in front of the passenger side cylinder head deck surface. That has the block suffix code. That number will give you a little more insight.

[xaztec]

I didn't see anything but wasn't really looking. What would I be looking for? I can go out and check.

[xaztec]

No, there's nothing at all near the deck on the right side or in front by the right deck on either block.

[DoubleVision]

On the cylinder deck pad, right behind where the alternator would sit is where these numbers would be, unless the block has been decked.
Some of the things you want to know about the markings are pretty basic.
First, the "clock" shows what time it was being made, and the letters, D A N stand for Day shift, Night shift, and I can`t recall what the A shift was, but this was working 10 hour shifts. The E 19 is the date code, the E stands for the month. So E in the alphabet is may, so it`s may 1st, the 9 is the year, which could be 1969 or 1979 or whatever years the block was casted. The 010 on the side of the block is simply the end of the casting numbers. The 010 and 020 indicate how much percentage of tin and nickel in the casting, which some will differ if any was used at all.
But as said, if you want to know what vehicles these came out of you`ll need the suffix code on the front deck pad. Also if I`m not mistaken, the block that has the M stands for GM of mexico and will be a target master replacement engine. On that block look by the casting numbers and see if you see "Hecho en mexico" that will tell you it is.

[1930u]

Your blocks were used commonly by Chevy and GMC from 1969 until 1980. Cubic inch displacement ranged from 302, 327 and 350. They were used in a variety of applications- Camaro and others, trucks, motor homes and industrial. They were also used for over the counter warranty replacement. And would have had a CE suffix code.

Your 4-bolt block was cast on January 18, 1978. I'm guessing it was a truck application engine but without the suffix code that someone previously mentioned there's no way to tell. I'm only assuming it was a truck block because they made 100's, of thousands of them. Over all there are probably millions of 010 blocks. They were good engine blocks.

[xaztec]

I can't find any suffix codes anywhere on either block. There's no "Hecho en mexico" either...which, I guess, is a good thing.

On the 4-bolt, can you tell me what all those numbers under the timing cover represent? i.e. 509, 776, G31, 512.

Thanks for all the info.

[Studebaker]

The suffix code is located on the block behind the altenator. It is a small pad just infront of the head mating surface. This is a area where grime accumulates, clean this pad and you will see the suffix code. It is usually a light stamped series of letters and numbers. By using a suffix code book you can determine from these numbers the date of build, engine, if the engine was a 2 or 4 barrel, the type of transmission used behind it and the vehicle it was installed in.

[flyin99]

Originally Posted by xaztec

I have two blocks. One is a 2 bolt main and one is a 4 bolt main. They're both casting 3970010. Rather than try to explain all the markings, I've taken pictures of them all. I'm trying to figure out specifically what engine these blocks were used for. Thanks in advance for your help.

First the 2-bolt

I have found the same block as you, with the M and all that. I sent pix to several race engine shops and Scott Pass from Competition Engines in Tennessee said the following:

Those are Canadian blocks with the boxed M and the clock on the side. They have a little thicker metal and are excellent blocks but becoming hard to get.
__________________

[xaztec]

Originally Posted by flyin99

I have found the same block as you, with the M and all that. I sent pix to several race engine shops and Scott Pass from Competition Engines in Tennessee said the following:

Those are Canadian blocks with the boxed M and the clock on the side. They have a little thicker metal and are excellent blocks but becoming hard to get.
__________________

Cool, thanks for the info!