Re: how many zl1 motors were made
 

http://i32.photobucket.com/albums/d46/RPOZ28/ZL1.jpg

This is a very old thread but I am digging it up because I have seen with my own eyes some old paperwork related to the ZL1 block mostly. It is an old paper file and I know the original source. It is legitimate GM prints and various internal notes. Most of it is from the early 1970s. I have not had the opportunity to look at all of it yet but may get a chance to look at it again soon. I believe the person who currently is in possession of it may be interested in parting with it if it was s worth their while. It looked to me like most of it was related to block 3946053 but it also looked like there were other part numbers in the file as well. Does anyone on here have any insight into the historical or monetary value might be?

Good scripture there Luke 10:27.

Who is the original source? I was a superintendent in production at Tonawanda MCP in the 70s. Maybe I know him?

It has historical value.

As for monetary value, ask the people that have been sitting on internal Chevrolet Engineering documentation for decades. Still waiting on the big payday. The people ready to write the book have given up in frustration. The number of people that care is shrinking fast.

As long as the Dog In the Manger act continues, the entire ZL-1 story will not be told.

Very well said William... The poster may be associated with those holding the documents....

I agree with all of you. The individual associated with these documents originally is long gone. The caretakers of them believe they have high value (I assume was told this by the original source). They are fearful of going public with them as they think there could be legal repercussions as the company is still in business. I believe they would destroy them if they thought they could risk being in trouble. I was brought into this because they trust me and I have knowledge on this stuff. I would like to make sure the historical part is preserved but I am guessing it won't be given away. I am considering making an offer to buy these documents but if I would do that, I would have a way to recoup my investment. If I were a rich man I would buy them and donate them to the historical cause but I'm not a rich man...lol.

Chevrolet doesn't seem to care much about 53-year-old engineering info. Plenty of Chevrolet engineering documentation was published in the Chevrolet by the numbers books.

Today you can visit the GM Heritage Center and request a part drawing. If they can locate it, they will provide a copy.

I have the 2022 Chevrolet Performance catalog. The ZL-1 block casting is noted: DISCONTINUED-Check dealer stock for availability.

I am curious as to what the difference was between the 3946052 and 3946053 cylinder blocks. Put me down for $20 US.

Agreed. GM does not care about old docs like this - there is no liability or risk here.

GM will not provide copies of prints. If they can find it, you may look at it and take notes.....

----I have been to the Heritage Center with a good friend and spent a whole day going thru reems of paperwork looking for particular stuff. Found many interesting things so it was a fruitful day. My friend went back and spent the whole next day as well. If there is a good enough reason you can make an appointment!....Bill S

Chevrolet by the numbers books are full of copies.

Yup, that was then, this is now.

Chevrolet gave the rights to Yenko to purchase ZL-1 blocks from the Winters Foundry in Canton Ohio. (with some restrictions).

The part number listed is 3952318

The letter is dated June 7 , 1974

signed by F. A. Duco , Director, Manufacturing Sales

Chevrolet produced other, different; aluminum big block castings that were not part of the ZL-1 program. Some were never sold to the public, provided to Chaparral and McLaren for their race cars. As of early 1968, they began development of an 'aluminum block L-88' that later became Corvette RPO ZL-1 for the 1969 MY. Due to poor sales, the ZL-1 program ended July 1969.

Chevrolet continued to develop aluminum big block castings for racing without liners or provision for a mechanical fuel pump. These were sold as bare blocks only, never used in production. Those and Yenko blocks are not considered ZL-1s.

The only true ZL-1 castings are 3946052 and 3946053, as used in 2 production Corvettes and 69 Camaros.

looking at the Yenko documents it looks like they bought about 200 of the ZL-1 blocks from the Winters Foundry after 1974.

These were required by SCCA for the Corvettes that ran the ZL-1 engine.

The other Yenko aluminum blocks were not legal to race in the SCCA Corvettes at that time.

Zora and Vince Piggins were involved with getting the blocks made.

The part number 3946052 is listed as the "cylinder and case rough "

The part number 3952318 is for the "cylinder and case assembly "

The 3952318 assembly has a parts list of about 20 parts including bearing caps and bolts, plugs, dowel pins , cam plate, and other small parts.

These Yenko documents are in the Mark Gillespie 2nd Yenko Era book. Includes a hand written note from Vince Piggins.

Do you know if those had YENKO cast into them?

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

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.

Yes, near the motor mount on the left side. ZL-1 blocks have a casting sequence number, a machining sequence number.

I have a small log of data on blocks that abruptly stops as of July 1969. Have not seen a later casting. They did a pilot run of ZL-1 blocks in the late '80s but used a different, darker alloy. A few of these blocks were machined and built. Somewhere I have a pic of unmachined blocks on a pallet.

Too bad, the entire ZL-1 story may never be told.

Yenko and Greenwood and others were still using the ZL-1 block in the 1970s for SCCA racing.

I remember an article on Greenwood showing about 15 blocks he had bought from Chevy. There must not have been many new blocks left by the mid 1970s.

Reason to believe Winters cast just under 600 blocks. Engine production eventually totaled 182: 80 "ME", 14 "MG", 54 "ML", and 34 "MM". I have heard there was a high scrap rate but no hard numbers. No matter, plenty of unused blocks around.

Another observation: have never seen and do not know of a CE ZL-1 short or fitted block. The ZL-1 Camaros I know of that had warranty engine failures were either repaired or had complete engine replacement with a converted ME code engine.

At this time, I do not know of a production ZL-1 Camaro built with a Holley #4296 carb. Some of Gibb's 50 were retrofitted; original owner history on one of the last cars built stated it was delivered with the L72/L78 #4346.