L88 Article by Ken Kayser

[Steve B.]

Re: L88 Article by Ken Kayser

When did open chamber iron heads show up on production engines? Were any '69 L-71s so equipped?

Duke

All 69 L71 and L89s used the closed chamber design. The 71 LS6 Corvette used the open chamber aluminum heads with the L71 piston design which brought the compression ratio to 9 to 1.

[Clem Z.]

Re: L88 Article by Ken Kayser

I believe that there may have been four open chambered L88s that went to racers in Jan of 69. As for production cars, the earliest one that I have seen were built in June with a 22xxx vin. I have not received the article but it's interesting to read some of the comments on open vs closed chamber heads on ZL1s. As I am sure that most people realize is that the second design L88s had several important changes vs the earlier motors. A new piston was used to along with stronger rod bolts as the 3/8 bolts were prone to failure during high rpm use. If the stock IT piston was used the compression ratio would be more like 9 to 1. It also used the holley double pumper carburator. The camshaft was also changed. It wasn't as easy as simply swapping out the heads. I can't wait to read the article as I find this stuff very interesting.

the engine i put the OC heads on that had CC pistons had 12.5:1 CC pistons so the CR was around 11:1

[Clem Z.]

Re: L88 Article by Ken Kayser

That did factor in Loren. When I wanted a crate L/88 open chamber engine, none available in the warehouses, I called Piggins on his direct line and just over a week the freight carrier delivered my engine to my local dealer. Parts manager could not understand how I got one and he could not.

back in the day stuff like that happened. as mrs clem used to say the care packages from GM or Katech arrived today. places like TRW even sent stuff because they knew i would give them the straight scoop. other places if the stuff worked they would keep it to themselves so they had a advantage. god i missed those days !!!

[Clem Z.]

Re: L88 Article by Ken Kayser

When did open chamber iron heads show up on production engines? Were any '69 L-71s so equipped?

Duke

there were so called OC cast iron heads on production engines in the early 70s BUT they were not the OC cast iron duplicate of the OC aluminum heads as these never made it into production. there were oval port OC CI heads used on 454 engines in the 70s that were similar design to the OC rectangular port high performance heads in the combustion chamber. i forget what the CCs of these chambers were.

[Clem Z.]

Re: L88 Article by Ken Kayser

When did open chamber iron heads show up on production engines? Were any '69 L-71s so equipped?

Duke

i believe the retangular port CI OC heads were to be installed on the still born 465 HP 454 corvette engine that never made production in 1970 but later were sold over the counter.

[Mark D.]

L88 Article by Ken Kayser

I love L88s. Coolest cars in the history of earth. I owned a super late LO coupe for years. It's a car that Stan Falenski has more time behind the wheel than I do.

I've been fortunate to judge a boatload of them, IT and LO. I am still solidly comfortable in my opinion that the LO motor began appearing in Corvettes post strike in 1969 and that would make it a much lower percentage of 69 L88s than the IT equipped cars.

Regards,

Mark

[Duke W.]

Re: L88 Article by Ken Kayser

The only big block iron head production engine from 1970 to 1974 was the LS5 ('71-'73), which became LS4 for '73 and '74.

These were all oval port heads, right? But what chamber configuration did they have?

The big block iron head castings appear to have changed every year, but that doesn't give much of a clue.

Duke

[Norris W.]

Re: L88 Article by Ken Kayser

i believe the retangular port CI OC heads were to be installed on the still born 465 HP 454 corvette engine that never made production in 1970 but later were sold over the counter.

When were the LS7's first available over the counter? The original owner of my L88 (who incidentally died last week) replaced the original engine with an LS7 crate motor and based on his recollection think it was done relatively early in '70. He sold the car not too long after, replacing it with a Motion Performance Camaro, also with an LS7. I'm unsure if the Camaro was a '70 or '71?

When did open chamber iron heads show up on production engines? Were any '69 L-71s so equipped?

If by production engines you mean those installed in cars rather than over the counter, 1971 in the oval port version. My recollection is that there were never any open chamber iron rectangular port heads installed in a car from the factory. Of course over the counter engines and marine engines had them from about '70 foward.

[Clem Z.]

Re: L88 Article by Ken Kayser

The only big block iron head production engine from 1970 to 1974 was the LS5 ('71-'73), which became LS4 for '73 and '74.

These were all oval port heads, right? But what chamber configuration did they have?

The big block iron head castings appear to have changed every year, but that doesn't give much of a clue.

Duke

those oval port heads were 3993818 but the ones used on the 454 pickup truck engines had the same shape chamber as the 3994025 OC CI retangular port head. i removed a set of these from a 454 pick up truck engine and installed the CC CI heads to raise the CR . i think i have a picture of the 3993818 heads and will post it.

[Steve B.]

Re: L88 Article by Ken Kayser

I took my early '69 L88 to Bloomington for Earthquake '88, my Gold L89 there in '89 and a friend's Monaco Orange late '69 there in '90 for Survivor (first L88 given Survivor status although a previous owner of the black '69 that may be the one that Mecuum is fixing to sell has claimed his was first and only as of several years ago). Anyway, at one of these three events someone was talking about open chamber L88's and said all the pre strike '69 L88's were closed chamber and the post strike open chamber. I can't recall who, or what year of the 3, but whoever/whenever it was seemed knowledgeable on L88 history and I've always passed that statistic along assuming it was true.

I agree, I think the claim that 56% of 69 L88s received the open chamber motor is pretty optimistic.

[Clem Z.]

Re: L88 Article by Ken Kayser

here you go the oval port so called OC CI heads

[Clem Z.]

Re: L88 Article by Ken Kayser

back in the day here is the kind of info i would get from GM and this was from a GM person who was working at smokeys when this was sent.

[Patrick B.]

Re: L88 Article by Ken Kayser

i have see written proof to that. i also have seen and worked on a ZL-1 engine with CC heads.

I believe Clem's experience with a CC ZL-1 involved a CAN-AM block made in 68 or earlier. It is a block with a casting number 0294550, and it is significantly different from a production ZL-1 block casting 3946052. Ironically, the famous GM pictures of the ZL-1 shown on the cover of the "How to Hotrod Big Block Chevys" block and the cover of Hot Rod magazine for December 68 are of this block with apparent CC heads.

The 0294550 block has a peculiar protrusion along the driver's side of the block for a large oil passage that the ZL-1 block does not have. Also it has a casting number on the front of the block below the intake manifold, and it does not have any Winters snowflakes like those on ZL-1 blocks. The attached pictures show the 0294550 block.

The open chamber 3946074 heads do not have the large plugs screwed into their ends that the earlier CC 392 and 842 heads had, even the Dec 68 castings on my Camaro ZL-1 that are apparently very early. The "official" ZL-1 pictures that show the 0294550 block show it with heads having the end plugs of the CC heads.

The 0294550 block I have was sold by Jim Hall to a drag racer in Midland, TX apparently because it was damaged while racing in Chapparel. I had not been able to find out much about the 0294550 block on the internet and was very suprised to notice that GM's pictures of the ZL-1 engine showed this block rather than the real production ZL-1. Maybe some of our GM insiders can shed some light on this block.

[Dick W.]

Re: L88 Article by Ken Kayser

Correct me if I am wrong Pat, but weren't all the Can Am blocks sleeved from the factory? I seem to remember that from the early Chevrolet Performance Manual.

[Michael H.]

Re: L88 Article by Ken Kayser

The 0294550 block has a peculiar protrusion along the driver's side of the block for a large oil passage that the ZL-1 block does not have. .

A few of those very early 0- aluminum blocks had part of an oil pump from a turbo 400 transmission mounted and driven off of the nose of the crankshaft. The pump location used the large oil passages that you describe.
I may have some prints on this somewhere around here.