You can't tell a DZ block by anything other than the assembly code stamped on the passenger side front pad. A 3970010 block in a DZ coded engine is the same 3970010 block in an L65 350/250HP engine, which is probably the same as one in a 307/200HP engine. It's just a block.

 

That is what I thought. We have a decent trade worked out for the block, and I want to be sure we are square. My feeling is regardless of the DZ stamp it is a highly desireable block craving attention. Thanks for the answer-

Rob

 

Originally posted by Mark C:
You can't tell a DZ block by anything other than the assembly code stamped on the passenger side front pad. A 3970010 block in a DZ coded engine is the same 3970010 block in an L65 350/250HP engine, which is probably the same as one in a 307/200HP engine. It's just a block.

Hey Mark:
Except for the 4 bolt mains?

Gary

 

Block is a block. All castings with a like casting number started out in the sand mold the same way, it was the machining that determined if it was going to end up with 2 bolt or 4 bolt main caps. 69 DZ's were 4 bolt, but so were some of the other engines. Mines an 010 350ci block, and it's a 4 bolt block.

 

JUST A REMINDER, THAT 307'S HAD A SMALLER BORE SIZE. NO 010'S USED.

 

I did see and read that the 010 and 020 casting on the front of the block, under the timing chain cover indicates the amount of nickel used on the block. A guy I know that restores Camaros told me that was also true. The higher the number, the higher the nickel content. I also found on all the true Z-28 blocks I have seen and some LT1's cast in 1969, they have a high casting mound in the lifter galley where the distributor goes through. Most of the blocks just have a hole at the bottom of the lifter valley. I read this is another way to tell it is a high nickel block. Jim

 

I think you'll find the 70 LT-1's have a 3970014 casting number on them, as do some of the late 69
Camaro blocks. Don't know if this results in any visual differences around the distributor hole or the lifter valley.

There can not be a difference in the shape of blocks (excluding machining difference) made with the same casting since they all came from the same mold. Wouldn't matter if they were cast from titanium (if you could cast titanium). There was a master male mold (OK a bunch of them)made off the engineering drawings and these were used to make the female sand mold that the cast iron was poured into to make the raw blocks. A change in the shape of the raw casting would require a different master mold to be made which is controlled by the engineering procedures at the casting plant. This would require a change in the casting number placed into the mold so the masters and the cast blocks could be traced.

 

I guess just to be clear, apparently this "mark" designating 302 DZ is a stamp or something that is added after casting. Like I said, we had struck a deal that was good for both, but he questioned the absence of said markings, whatever it is supposed to be. I am supposed to see him today and I will inquire further as to what this is supposed to be. Thanks again-

Robert

 

Mark,

I had an original 1970 LT-1 and it was a 3970010 block out of a Norwood car.

 

Was it visually any different than any other 3970010 block? Did it have this mound near the distributor hole mentioned above?

 

Mark

I did not notice any difference between my LT-1 block or any other 350 block. I am sending you pictures of the block.

 

I have an original 70 rs/Z28 with the 010 block. I'm going by memory and pictures taken of the block before the rebuild.
On the front under the timing cover it reads 010,020 then a 43 below that. The dist hole is probably 4-6mm below where the top of the last lifter hole rises above. I don't have another 350 block to compare it to so I can't claim there is a difference??
I do know 100% this is the original LT1 motor for my car with the ctb code and the vin# stamped above the oil filter.

Dave

 

The 3970010 block casting that ended up machined, assembled, and stamped as a "DZ" engine was no different than the 010 casting used for any of its other applications (they made seven million "010" blocks). Although there were minor running changes in the casting from time to time over its ten-year run, none were specific to "DZ" or any other final engine configuration. When it came out of the Saginaw foundry and was trucked to Flint Engine for machining and assembly, it was just another hunk of cast iron with 3970010 cast into it, and at that point nobody had any idea what its final configuration or usage would be.

 

John Z,
All the 010 Z/28 blocks that I have seen have the shot peened main caps with the "N" markings to signify that they are nodular caps. Would this not mean that the Z/28 blocks were in fact different than the run of the mill 010 blocks which did not have better mains?

As far as the topic above that speaks to the distributor pockets (mound), I have only seen this evident on the 386 / 618 blocks as well as the 388 castings. Never seen this on an 010 block, but not to say that they don't exist. Just never seen an 010 cast this way. Any pictures of an 010 with the distributor pocket would be appreciated?

 

Originally posted by hugger_sixty_nine:
John Z,
All the 010 Z/28 blocks that I have seen have the shot peened main caps with the "N" markings to signify that they are nodular caps. Would this not mean that the Z/28 blocks were in fact different than the run of the mill 010 blocks which did not have better mains?

The main bearing caps were added at Flint Engine during the block machining process as add-on assembly parts and had nothing to do with the raw "block", which was cast 40 miles away in Saginaw. In 1969, all factory 4-bolt bearing caps on 350/300, 350/350 (Corvette L-46), and 302/290 engines were the new nodular iron caps.