ZLX question

[Musclecarkid]

Found this in my Motion Performance Guide (copyright 1976)

"ZL-X...427 cubic inches, 650HP, solid-lifter .585-605 PHASE III cam, choice of gear- drive injected, 850, 950, or 1050 cfm Holley carburation on reworked aluminum high-riser, cast iron open chamber heads with special 12.8 to 1 pistons, 69 L-88 blueprinted four-bolt main block. This is a very special M/P competition engine."

IMO, I believe this was a crate motor from GM that Motion tweaked on a little.

Similar to an iron head, open chamber L88 or ZL1 with a cam change and blue printing.

I believe the ZL-X iron open chamber heads were 026's available in late 70 or early 71 as an over the counter piece. They were replaced by the 990's around 72-73 and used till the mid 1990's.

The ZL-X heads were used on 427 and 454 engines according to this catalog.