ZL-1 Camaro engine VS early Can Am engines

[GMH454]

My first interest in these was through Corvettes and racing. Greenwood used them, Warren Agor ran one in his Group 6 Camaro in Trans Am / IMSA etc. Jim Hall ran a type of ZL-1 in around 1967. There is a photo of the engine out of the car showing the prominent front ribs on the block.
I have always read that the early Can Am engines were different from the COPO and later engines. Does anyone know what these differences were. (Note not talking here about the Reynolds blocks that McLaren ran ) Have read that there are differences but never see anything mentioned.
Anyone know of any references to another site would be appreciated.

[JoeC]

From what I read, it was Roger Penske who worked with Chevy to make some Aluminum small blocks while he was employed at Alcola Aluminum, CO. in early 60s. They were used in the Grand Sport and Hall's Chaperals. When the BB Chevy was released Hall used the alum BB based on the 4.250 bore 427. This ZL1 block proved to be a weak design and did not hold up to rigors of 8000rpm CanAm racing. So Chevy did a new block with 4.440 bore which looked similar to the ZL1 but was stronger using a siamese cylinder design. The ZL1 blocked was used in road racing Corvettes because the Can Am block was illegal and the ZL1 did well where RPM was not as high. The top drag racers used the CanAm block for match racing in 69 and in Pro Stock starting in 1970. The CanAm BB Chevy alu engine went on to dominated CamAm racing beating all contenders including Ford, Porsche and Ferrari until Porsche went crazy and built the duel turbo 1100hp cars. This CanAm block was also used by Bill "Grumpy" Jenkins to win the first ever Pro Stock race in Pomona 1970. Don Yenko raced a ZL1 powered 1969 Camaro at Daytona or Sebring. I asked a ex-Yenko race machanic about this and he confirmed it. He said it was very fast and stayed with the top Corvettes but Don blew it up. He said he still has some of the mangled valves from it.

[GMH454]

Thanks Joe, knew I could rely on you. Some very interesting stuff there. Have you seen the photo I am talking about, it would be around 1967 and has I beleive, the winged coupe in the back ground with a ZL-1 on chains in the foreground. Sure looks like production ZL-1 from the outside .
Not surprised that they could not handle the Can Am work load, but it might not have been just the revs but the 3 hour race duration that was the real killer. I still think he won a 6 hour enduro in England with it so it was no grenade. Got to think that those blocks would flex a bit, the chassis were not that strong. I beleive with injection those engines would produce near to 700lbs of torque, this lack of endurance reliability was also a constant problem for the Vettes when running cross ram injection , until they went to Yenkos (beleive Pickett won the Trans Am in 1978 against the 934 Porches with a Yenko, probably the BB Vettes last win). Was Yenkos ZL-1 detuned, Bob Jane detuned his to 11-1, so it would live in the Aust touring car season. Only lost one engine in 2 years.

You constantly hear the 2 engines are different, but not sure they would have needed to be. Could just be another Chevrolet myth.

[Don_Lightfoot]

I was a very big Mark Donohue fan and used to go to Mosport on a regular basis to watch him race. I believe the first time I saw him he was driving the Sunoco Special which was competing in an "open wheeled" race along the lines of the F1 cars, this was probably around 1965 or 66. It was then on to the Trans Am Series for him which I loved. However, there was nothing like the sound, appearance and outright performance of those Aluminum blocked CanAm cars. I may be wrong, but I think Mark still holds the single lap record at Mosport to this date in that CanAm Car. I lived in Oshawa at the time and the teams used some local fenced yards to store their cars overnight. I remember pulling into a yard one night and saw Mark by himself leaning against a building at the opposite end to where all the other racers and reporters were. I said to my wife "That's mark Donohue way over at the other end" and we drove over there. Had a real long talk with him which definitely made my day. CanAm Racing was awesome to say the least.