"Prior to building the IMSA car I had raced mostly SCCA amateur races in a series of production based Corvettes - a 1957, a 1965, and a 1969. In July 1972 IMSA ran its first West Coast race (at a tiny little track called Las Vegas International Speedrome) and I managed to win that race with my 1969 Corvette, collecting $300 for the overall win plus $30 for being first in GTO. In 1973 SCCA adopted the FIA rules for the TranAm series and I ran the same car at the Edmonton (Canada) TransAm. I continued running that car through the 1974 season at any TransAm and IMSA races that were located in the western half of the United States. At the time John Greenwood was developing some aerodynamic bodywork that was available through Chevrolet, so we began to alter our car to follow those developments.
After the 1974 season it was time to develop a new car that better fit the FIA rules, so I began the process buy buying a stock Corvette frame (as still required) and dragging it to an acid-dipping facility in southern California for some major weight reduction. I started the construction of the new car using that frame and then the rules changed to allow tube frame construction. There wasn't time to completely redo the chassis that way, so I cut off the front of the stock frame and built a partial tube frame car for the 1975 season. I cut off the rear section of the frame and redid that area of the car for the 1976 season, but for the life of the car it still retained a U-shaped section (two side rails and a rear cross member) from that original acid dipped frame.
We built the car originally as a roadster, but with Greenwood bodywork and a rear spoiler. I think we converted it to a coupe for the 1976 season (whenever the AAGT rules came out) and added a homemade aluminum wing. I was an aerospace engineer working for Lockheed Missiles and Space Company, so I went to the Lockheed library and found a NACA wing profile that looked promising and that's what we used. My crew chief at the time, John Whitmore, worked for a large auto body shop - Automotive Enterprise - so he had the talent and resources to create bodywork features like a massive front air dam, radiator exit ducting through the hood, engine air ducting through the hood, and side NACA dusts for oil coolers in the doors. As a result, even though we were on a pretty small budget relative to most of my competitors, we always had a pretty swoopy looking car that was aerodynamically and functionally competitive.
The motor started as the carbureted 427 all-aluminum Chevy ZL-1 that I'd run in my production car in 1974. Somewhere I came up with what was called a Reynolds block (a large 4.400 bore aluminum block cast by Reynold Aluminum that was the basis for the 494 CID engines used in the old CanAm cars). When you used the production 427 crankshaft you got 465 cubic inches, which is what we ran. We also managed to acquire a Lucas fuel injection unit from the old Chapparal CanAm cars. The manifold was a giant magnesium individual runner crossram setup that required a very large bubble in the hood. We soon learned that the intake runner length was way too long to allow the engine to run at the 7500 rpm range we would have preferred (it just wouldn't run over 7000 rpm) but it had phenomenal torque. We could only get 700 horsepower, but the torque was right at 600 lb-ft. I initially only had one of the Chapparal manifolds, but I did a little trade with Greg Pickett for a second one that he had (he ran the better, but more expensive, Kinsler manifold on his car). The trade involved the final TranAm race of the 1978 season in Mexico City. To win the series he just needed something like a 7th place finish, and my car was pretty well assured of about 4th or 5th, so I agreed that he could use my car as a backup if anything happened to his in exchange for the manifold. As it turned out he won the race in his own car, but I still got the manifold.
Because of the huge engine torque we had to run really big wheels and tires to minimize wheelspin. Our rear wheels were 21 inches wide by 15 inches diameter, and the rear tires were some Super-Modified tires made by Goodyear. On the front we ran 15 inch wide by 16 inch diameter wheels. Even with those wheels and tires you had to be pretty gentle with the throttle until you got into 4th and 5th gears. We initially ran a GM Muncie M-22 4 speed transmission, but (I think) for the 1978 season we redid the car around an LG-600 Hewland transaxle. That gave us great gear availability, but the pinion gears just weren't up to the torque, so we had to replace the crown and pinion set about every 3 hours. It placed a lot more weight on the rear wheels and really did help traction out of slower corners."