ZLX question

[Schonyenko2]

I have seen Nickey sales slips showing ZLX motor assemblys on this site. Joel talks about his ZLX motored cars many times in the magazine articles. The ZLX in this car was sold locally. I'm sure they exist in maybe more than 1 form.What I want to know are the part numbers for the short block, and the rest of the motor. This one does show a CE ft pad stamp. I don't think these crate motors existed before 71. Joel talks about them before that. He once told me he got the heads out the back door of GM.

[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.

[Schonyenko2]

I agree. Somewhere though, there must be a reference to ZLX in a Chevy service parts book. The counter guys at Nickey, and Ericksen's where this motor was installed weren't pullin the designation outta thin air.

[ORIGLS6]

Ken, check your e-mail.
I have an article from the April '72 issue of Hi-Performance CARS, featuring a '72 Chevelle with the ZL-X option. Also in the October '71 issue are ads from M/P showing the "Super Trick Open Chamber Cast Iron Heads" (Racer's Net... $395./pair). It shows a M/P Part No. of 3946028-70....... maybe NOT a GM number! (but worth checking)

Also a Complete 427 inch ZL-X engine for $1395.00 and the 454 version for $1995.00.

[markjohnson]

The mysterious ZL-X. I believe musclecarkid is correct about the 026 cylinder head being the correct ZL-X cylinder head. I had set on a motor about 15 years ago with '1971' casting dates on them and had always wondered what their original application would have been. In 1971, the only rectangular port cylinder head being used for assembly line production was the '074' aluminum head on the very rare 1971 LS6 Corvettes. I just concluded that it must be an over-the-counter cast iron, open chamber, rectangular port cylinder head used for crate engine or even a service replacement if someone wanted to use cast iron heads on an L-88 motor in marine application. The 026 was the forerunner of the common 990's and 188's that would be used on LS6's and LS7's for the next couple of decades. By the way, the 427 I had these on was really a runner!

[68l30]

Didn't Joel discuss this at the SCR Banquet? I have the tape at home....He mentions something about them being nothing more than a GM part number with his marketing crew making up the ZL/X name.....I remember him thinking this was funny...I know I did.


Steve

[69SSZL1]

From page 150 of vintage "How to HotRod Big Block Chevys" in the Heavy duty parts list they show chevy part #3970699 as a partial engine assembly L-88 427: "430 HP L-88/ZL-X short block with 12.5:1 c.r. pistons for use with open-chamber heads, 4-bolt mains." I still dont know what ZL-X refers to.

[Schonyenko2]

I went and found my old copy of that book. Mine may have been an older edition as there was no mention of the ZL-X. But in the process of looking for it, I came across my old Nickey, and Berger catalog, and they both list it. Berger:1/2 engine assy/short blk, 0699 427/430 ZL-X 12.0 to 1 open chamber. 1/4 engine assy: fitted blk 8656 427/430 ZL-X 12.0 to 1 open chamber.
Nickey's reads: 9960 427/450 12 1/2 floating wrist pin, 4 bolt solid cam ZL-X L88 open chamber. I think they may have the part# backwards.
So it basickly is, with 026 open chamber heads, a cast iron ZL1.
It appears this was kinda the transition/ evolution to the LS7 454 crate motor.