Block Casting Numbers

[Cecil L.]

I have a general question on casting numbers that I have not been able to find an answer to. Does anyone know just when the last three digits of the block casting numbers started showing up on small blocks? I think it was probably in the mid 70's but haven't found any documentation.

[Cecil L.]

Re: Block Casting Numbers

OOPS, Sorry about the duplicate post, I edited the misspelled subject line and somehow generated another post.
Spmetimes it would be nice to have a delete post option.......or maybe there is and I just don't know how.

[Dan A.]

Re: Block Casting Numbers

Block Casting numbers were 7 digits till maybe the late 70s or early 80s. They were on the rear of the block on the left side bell housing mounting flange

If it is the a 3 character suffix in the engine build stamp that you are thinking of there are a very small number of them in 1966 passenger cars with an H or an R at the end designating Holley or Rochester carbs.


In 1970 all the suffixs became 3 alpha characters.

[Cecil L.]

Re: Block Casting Numbers

No. I'm talking about the last 3 digits of the casting number appearing on the side of the block in large charcters in addition to the full casting number on the top of the bell housing mounting flange.

[Steven B.]

Re: Block Casting Numbers

Cecil, I am having a hard time posting picture and will continue to try. My '57 Corvette 245 HP that I bought Nov, 1964 has 548 cast on the side. Having spoken to the previous owners from new it is the original block. It has cast K266 which is in line with the build date of mid-Dec. '56.

Steve

Got it!

[Cecil L.]

Re: Block Casting Numbers

Steve,
That's interesting. I've never seen it on an early block, although I have seen some late 57 548 castings with X58 in small characters on the side which might seem to indicate some late 548 castings may have been used in early 58 MY.

[Michael W.]

Re: Block Casting Numbers

Cecil-

Could this be part and parcel of the mold pattern number story, where the last three letters of a final casting number were used on some/all of the individual patterns that make up a cylinder case?

Many 70's vintage 0010 cylinders cases have '010' and 020' in various spots. This gave rise to the high nickel/ high tin content myth. In particular, the numbers are seen most often on the front of the case under the timing chain cover.

[Cecil L.]

Re: Block Casting Numbers

Could be just that......or possibly for the benefit of the guys assembling the engines since they are cast upside down.

Yep, that " high nickel" block myth just won't go away but is easy to counter. Just look at any small block , W block and probably BB front and you will find the last 3 of the block casting numbers of all blocks using the same front pattern, in same year production. "010/020 are the Flint blocks and 014/024 are the Tonawanda blocks in those years...one being 350 and the other 307.

[Joe L.]

Re: Block Casting Numbers

Could be just that......or possibly for the benefit of the guys assembling the engines since they are cast upside down.

Yep, that " high nickel" block myth just won't go away but is easy to counter. Just look at any small block , W block and probably BB front and you will find the last 3 of the block casting numbers of all blocks using the same front pattern, in same year production. "010/020 are the Flint blocks and 014/024 are the Tonawanda blocks in those years...one being 350 and the other 307.

Cecil------

I believe there were high nickel blocks but the "010/020" casting marks do not identify them or, for that matter, have anything to do with them. I used to think they did, myself, but I long-ago confirmed that those marks are unrelated.

[Cecil L.]

Re: Block Casting Numbers

You're right Joe. There may have been. I'm sure they were adjusting the metallurgy during the years. It's just that those "010/020" numbers have nothing to do with it. If anything would be an identifying feature, it would likely be the part number.

[Cecil L.]

Re: Block Casting Numbers

So, let me ask this a different way.
Could those of you who have a lot of engines/blocks laying around or can view the side of your engine in the car next time you are on your back under it, take note as to whether or not it has the 3 big numbers cast on the side of the block and what year it is?
I suspect this will be found in mid 70's and later, but would like to confirm. Although it could possibly have begun as early as 69 according to one block I have with a casting date of A 28 9, I suspect it's really 79, not 69.

[Michael W.]

Re: Block Casting Numbers

Cecil-
A '79 cast block should have a squarish stamp pad as opposed to a rectangular pad as seen on earlier engines.

[Joe L.]

Re: Block Casting Numbers

So, let me ask this a different way.
Could those of you who have a lot of engines/blocks laying around or can view the side of your engine in the car next time you are on your back under it, take note as to whether or not it has the 3 big numbers cast on the side of the block and what year it is?
I suspect this will be found in mid 70's and later, but would like to confirm. Although it could possibly have begun as early as 69 according to one block I have with a casting date of A 28 9, I suspect it's really 79, not 69.

Cecil-----


My original 1969 block, GM casting #3970010, has no numbers cast on the side.

Another 3970010 block that I purchased new from GM in 1975 has no numbers cast on the side.

My 1992 LT1 block, GM casting #10125327, has the number "327" cast on the side.

[Mike E.]

Re: Block Casting Numbers

Cecil------

I believe there were high nickel blocks but the "010/020" casting marks do not identify them or, for that matter, have anything to do with them. I used to think they did, myself, but I long-ago confirmed that those marks are unrelated.

I was reading one of David Vizard books last night. He mentions the 010/020 marks and says that it's related to high nickel content. I guess it just shows how these myths never die.


Mike

[Michael W.]

Re: Block Casting Numbers

Vizard is one of the originators/propagators.

I was reading one of David Vizard books last night. He mentions the 010/020 marks and says that it's related to high nickel content. I guess it just shows how these myths never die.


Mike