how many zl1 motors were made

[William]

Do you know if those had YENKO cast into them?

Seen a few like that, one did not have coolant passages.

[JoeC]

The Yenko ZL-1 blocks did not have the Yenko name on them.

On the Winters invoice the ZL-1 blocks have a note - (no trade name)

The Yenko blocks have a note - (with Yenko name plate)

There are photos of two blocks , one has the Winters snowflake and the other block has the letters "YENKO" in the same place where the snow flake is on the other block.

Did the 1969 ZL-1 blocks have a date code like an iron block?
The ZL-1 blocks that Yenko had made would be after 1974 but not sure if they had a date code on them.

There are letters back and forth with Bill Porterfield with an agreement to use and promote the Yenko block. dated Dec 1978 . I know Bill had a company called Mid Engineering and built a mid engine 1978 Olds 442 and a Kelmart GT using Olds engines but may have also used the Yenko block.