ZL-1 blocks

[William]

If there is a difference I have never heard what it was. Some of the earliest production ZL1 Camaros have the '053' casting.

Chevrolet produced a few varieties of aluminum big-block castings back in the day. The earliest [1967] were race parts only, provided to Jim Hall/Chaparral Cars for Can-Am racing. For 1968 McLaren was included. These blocks were significantly different from later production blocks, probably had 0- casting numbers. At this time the term 'ZL1' did not exist. When Chevy decided to offer an aluminum block option for the L-88 Corvette it was assigned option code ZL1. It only applies to castings 3946052 & 053. The latest true ZL1 block castings were produced July-August 1969. Later [1971-1972] Chevy did another aluminum bb casting exclusively for racing.

Be aware that in the late '80s Chevy ran off a number of 3946052/3 castings on the original tooling. They used a different, much darker alloy that does not match the older heads. Some of these blocks are around, machined and raw castings.

http://www.camaros.org/copo.shtml

[EZ Nova]

Thanks William. I didn't know of there 80's version of the 052/053 blocks. 052 are what I'm mostly looking for info on. And what does the smaller "2" indicate?

Thank you

[COPO_Anders]

Originally Posted by William

If there is a difference I have never heard what it was. Some of the earliest production ZL1 Camaros have the '053' casting.

Chevrolet produced a few varieties of aluminum big-block castings back in the day. The earliest [1967] were race parts only, provided to Jim Hall/Chaparral Cars for Can-Am racing. For 1968 McLaren was included. These blocks were significantly different from later production blocks, probably had 0- casting numbers. At this time the term 'ZL1' did not exist. When Chevy decided to offer an aluminum block option for the L-88 Corvette it was assigned option code ZL1. It only applies to castings 3946052 & 053. The latest true ZL1 block castings were produced July-August 1969. Later [1971-1972] Chevy did another aluminum bb casting exclusively for racing.

Be aware that in the late '80s Chevy ran off a number of 3946052/3 castings on the original tooling. They used a different, much darker alloy that does not match the older heads. Some of these blocks are around, machined and raw castings.

http://www.camaros.org/copo.shtml

I´m a bit confused about the blocks being produced in the 80`s, since Yenko got the rights to the blocks in 1976 and changed the tooling to reinforce the blocks. So what did happen back then ?

[William]

Originally Posted by COPO_Anders

I´m a bit confused about the blocks being produced in the 80`s, since Yenko got the rights to the blocks in 1976 and changed the tooling to reinforce the blocks. So what did happen back then ?

Yenko may have had rights to use the tooling; just not exclusive rights.

The finished block I saw photos of is a 3946053 Winters casting, circa 1984. Very dark grey.

[COPO_Anders]

Originally Posted by William

Yenko may have had rights to use the tooling; just not exclusive rights.

The finished block I saw photos of is a 3946053 Winters casting, circa 1984. Very dark grey.

Ok, but I was thinking if the tooling was changed by Yenko to make the blocks stronger, then the 1984 GM-blocks would not look the same as the blocks made before Yenko produced them. But of course they could have changed the tooling back to the way it was originally.