ZL1 or Yenko Block?

[Ed Cunneen]

When Yenko purchased the rights to manufacture the ZL-1 engine from Chevrolet, They started with the GM castings. Winters notified Yenko that they could not use the Winters insignia on the blocks. Hence, the W in the snowflake was removed and the aluminum foundry stamped in their initials. Yenko stamped their alpha numeric inventory number in the timing chain area of the block. These blocks did not have an inventory or date cast on the side of the block. The Yenko blocks evolved in construction and appearance over time.