ZL-1 block versus Can-Am block?

[Grumpy's Toy VIII]

Figured I might as well follow up with the actual difference between the 427 Zl-1 and the GM/Reynolds 430 Can Am in Bill Jenkins words from a 1970 article.

Source: Super Stock & Drag Illustrated July 1970

Jenkins was asked "can the standard 427 be competitive against the 430 or Can Am short stroke engine in Pro/Stock."

Jenkins replied: The Hp difference is negligible. It's the range with the 430 that makes the difference. He continued, the difference is 10 - 15 at peak and the peak for the 427 is 7,200 and +7,500 for the 430. At 7,200 there is no difference and at 7,600 - 7,700 the 430 makes 10 - 15 more hp than the 427 at 7,200. The 427 is definitely downhill at 7,700 - 7,800 being approximately -40 Hp say from 660 - 620.

The 430 climbs from 7,200 with about the same power to say 10 hp more at 7,500 and then maybe 15 hp more at 7,700; at 8,000 it is back to about the 7,500 power output.

SS & DI then asked how many of these engines are there ? Jenkins replied, 70 blocks were cast and distributed among 10 different Can Am teams and 6-10 of the blocks were given to potential or actual drag race users.

Note: very few Can Am blocks were cast with fuel pump bosses but the majority of all the early Can Am blocks were sleeved.

Note: Jenkins eluded to Reynolds experimenting with linerless blocks to increase bore size to 4.500.

I'd like to add that these engines weigh in the mid 400 lbs. range and when the mcLaren M8D/3 was subsequently tested by ex-F1 driver and double Le Mans winner JJ Lehto, the Finn declared M8D/3 to be “the fastest thing I have ever driven…”

[Carleen]

What you have there is an Experimental / Prototype Block.
They start with 0- and I have heard that only 20 Block were made of 0-326711 and they were cast -68. In 1969 3946052 - 3946053 Can Am Block were produced

[Grumpy's Toy VIII]

Carleen, agreed Reynolds prototype for GM. I have worked with and documented 21 variations of the GM aluminum blocks.

The 0-326711 you mentioned is definitely Can Am only. I have seen none with provisions for a mechanical fuel pump and agreed that mold was 68 only. It is also 4.440 bore and does have sleeves.

Who did you hear the production run number from ? That is interesting, I have never heard a definitive count other than from Bill Jenkins and Smokey Yunick who both state 70 short blocks cast between 67-69. This is Reynolds casting, not Winters. Different block, yes, even those that share the identical mold numbers:
3946052 and 3946053.

The Reynolds and Winters were cast from different alloys.

However, GM did turnover casting 052, 053 and 040 to Winters for '70 and '71 with big bore molds for Can Am teams.

If your into the Can Am stuff we should compare notes. A small group of us here in the USA that work on these are comparing notes to combine all this data and get it to those who restore these engines.

[Carleen]

I have one of the 0-326711 Blocks.
I heard that Chevrolet ordered 20 Blocks (minimum order) of all 0-blocks.
Its the third Prototype / Eperimental casting of CanAm Big Block
They were supposed to be scrapped after trying them out but came out the back door to Racers. WDC Casting.
BTW Mine have provision for fuelpump.

[Carleen]

I have seen some 3946052 Can Am Block on ebay with Casting date early 69. Also bought one of these but got into trouble with the seller

[Carleen]

Heres what I have found out.
And I thought WDC means Winter die casting

Can-Am blocks 68/69 - Winters
# 0-294550 = 4.250" bore with steel liners Experimental Prototype 67-68 Dry sump (427 ci)
# 0-321270 = 4.440" bore with steel liners Experimental Prototype 68 no boss for mechanical fuel pump(430, 465 ci)
# 0-326711 = 4.440" bore with steel liners Experimental Prototype 68 (430, 465 ci)
# 3946052 = 4.440" bore with steel liners (430, 465 ci)
# 3946053 = 4.440" bore with steel liners (430, 465 ci)

Can-Am Block 70 Winters
# 3946052 = 4.440" bore with steel liners (494 ci)
# 3946053 = 4.440" bore with steel liners (494 ci)

Can-Am blocks 71-72 - Reynolds
# O-399204 = 4.5" bore and steel liners (509 ci)
# O-495102 = 4.5" bore and no liners

ZL-1 Factory blocks - 1969 - Winters
# 3946052 427 ci.
# 3946053 427 ci

ZL-1 Factory blocks - 1997 & up
# 3946053 427 ci.

# 3992038 may be 4.44" bore w/ Liners - era?.

# 3946052 Yenko Casting LC 427
# 3946053 Yenko - Casting has YENKO
# 3946053 Yenko - Casting has Y E N K O
# 394605Y Yenko - Casting has Yenko Crest Logo

[Kered-TCracingCA]

Originally Posted by Carleen

Heres what I have found out.
And I thought WDC means Winter die casting

Can-Am blocks 68/69 - Winters
# 0-294550 = 4.250" bore with steel liners Experimental Prototype 67-68 Dry sump (427 ci)
# 0-321270 = 4.440" bore with steel liners Experimental Prototype 68 no boss for mechanical fuel pump(430, 465 ci)
# 0-326711 = 4.440" bore with steel liners Experimental Prototype 68 (430, 465 ci)
# 3946052 = 4.440" bore with steel liners (430, 465 ci)
# 3946053 = 4.440" bore with steel liners (430, 465 ci)

Can-Am Block 70 Winters
# 3946052 = 4.440" bore with steel liners (494 ci)
# 3946053 = 4.440" bore with steel liners (494 ci)

Can-Am blocks 71-72 - Reynolds
# O-399204 = 4.5" bore and steel liners (509 ci)
# O-495102 = 4.5" bore and no liners

ZL-1 Factory blocks - 1969 - Winters
# 3946052 427 ci.
# 3946053 427 ci

ZL-1 Factory blocks - 1997 & up
# 3946053 427 ci.

# 3992038 may be 4.44" bore w/ Liners - era?.

# 3946052 Yenko Casting LC 427
# 3946053 Yenko - Casting has YENKO
# 3946053 Yenko - Casting has Y E N K O
# 394605Y Yenko - Casting has Yenko Crest Logo

I know this is a slightly aged thread, but for my first post here in this forum, I can help this history. Covering the Yenko blocks, the first batch commissioned by Yenko was thru the Winters people, so they had the snowflake. Then Yenko bought the molds and Winters asked him to knock off the snowflake for his personal production.

For the 1967 year, Chevrolet was building limitedly 427 Aluminum engines, going out to Chaparral/Hall. So 0-294550 were this batch. They lost about 11 of them in race testing! First ran at the 1967 Daytona 24 where one 2F was fitted, and one 2D modified was fitted, due to the other Team 2F, not being ready. They won Brands Hatch with this engine in 1967. Also these could be configured either internal dry sump or wet sump. I have put up some pictures up of this in the last thread on Corvette Forum (TCracingCA) showing this, in the recent thread talking of a White ZL-1 clone selling on Ebay.

For 1968 to the dissatisfaction of Jim Hall, Chevrolet opened it up to offering supply to all Teams with the next version 0-321270 (I believe 20 produced). They were working on revisions, and due to supply demand, they released 0-326711 upping production and supplied to more outfits, 60 units out to Can Am and like Drag Racer Grumpy Jenkins got 3 initially, might have acquired 2 more, along with other outfits like Motion. As these could be built with the famed short stroke and big bore, in 430 or 465. These were the first of the Chevrolet units, that get confused as being Reynolds 390 units.

For 1969-onward, these Chevrolet units made using 356 aluminum (preceeding the Reynolds 390 Alloy program), Chevrolet finally gave them a Part # and made some available to select Dealerships over the counter. As these were designed to go 430, 465, they are as said with the proceeding 0-dash units, confused often with the Reynolds 390 units that would come later. And this engine was thought to be the 454 version of the ZL-1 mistakenly. I have to study the 0-326711, the ZL-1, and this #3992038 block side by side, but I think this latest has some of the characterics of both the Chevrolet 356 Alloy series and the ZL-1. The ZL-1 needed some clearancing for 4.0 stroke and this latest engine had that done.
Part #3992038.

They had problems with the larger displacement sizes 441 (.060 overbore) & 509/510 (.060 overbore) especially, due to the cylinder bores being so close to the head bolts, so they would get fracturing. I can elaborate more on this later, like core shifting. Therefore to solve a number of issues, they went with Reynolds and their improved Alloy and better production casting techniques.

Reynolds 390 only offered a Block which became Chevrolet Part #3965755 for 430, 465, 495

Next Chevrolet was working with Reynolds for bigger bores and plating techniques, different piston plating, etc. they had larger bore development happening under
0-399204 & later 0-495102, but the Can Am series died.

A few ZL-1 units were found to be able to be built in large displacement, in an attempt to keep competitive to the Porsche 917/30 & 917-10, until the last year of the old Can Am in 1974, when a gas consumption formula negated the sheer horsepower advantage of the Porsche Turbos in 1972 & 1973, and thus Shadow won that final year.