During the mid-60's, pony cars were hot. The Ford Mustang was selling so well the other manufacturers came out with their own version of the short trunk cars. Owners and enthusiasts started taking their pony cars to the race track making sedan racing ever more popular. SCCA began to take notice and for 1966 established a sedan class with a National Championship category. The SCCA set up Group 2 cars under FIA Appendix 2. The amateur classes were based on displacement: A - 2000cc to 5000cc; B - 1300cc to 2000cc; D - under 1000cc. The Championship series included over 50 amateur races leading to an invitational American Road Race of Champions (ARRC) for the top three sedan class finishers in each of the seven geographical divisions.
A professional series was a established called The Trans-American Sedan Championship. This series of races was made up of seven professional races at different tracks across the US. The manufacturer with the most points at the end of the series would win the first ever Manufacturer's Trophy. The Trans-Am races, as it became known, ranged from 200 miles to 2,400 miles. The races ran from 2 hours to 24 hours and required pit stops for gas and tires.
Group 2 cars were divided into only two classes, over 2 litres and under 2 litres. The maximum displacement was 5 litres or 305 cid with a maximum wheelbase of 116 inches. Plus eligible cars had to seat 4 people eliminating the 65 GT 350s. In the beginning, the GT 350s were set up as two seaters to qualify for SCCA's Class B Production. The rear sears were removed and replaced with a fiberglass shelf. Ford wanted the Trans-Am Manufacturers Trophy. After the great success of the GT 350 fastbacks, Ford immediately turned the project over to Shelby American.
Shelby American built sixteen 1966 Group 2 Notchback Mustangs, all for sale to independents. Chuck Cantwell, GT 350 Project Engineer and Jerry Schwartz, fabricator & mechanic were given the job of developing and prepping the cars. The Mustangs were built to GT 350R specs. The main differences between the Group 2 cars and the GT 350Rs were cosmetic. The Group 2 Mustangs were required to be close to stock with steel hoods and front ends. The GT 350Rs had fiberglass hoods and front aprons, plastic side and rear windows. The Group 2 cars used glass windows. Stock interior and four seats were also required for the Group 2 cars.
The GT 350Rs and the Group 2 Mustangs had a lot of similarities. Both cars had:
The Group 2 Mustangs were based on the Mustang GT. All Group 2 cars had the stock GT package including fog lights in the grilles. The lenses and bulbs were replaced with high intensity driving lights for better use during the night driving in some of the Trans-Am races. Most Group 2 racers came with a 1/2" rear sway bar and a Panhard rod. Some of the cars came with a scooped out fiberglass panel between the passenger compartment and the trunk allowing a spare tire to be mounted. The spare would not fit in the trunk with the larger gas tank. A spare tire was not required during racing. It is possible this option was shared with the four Group 1 race cars Shelby America sent to Europe. This a rare item to see today in restored cars. The SCCA required a metal bulkhead between the driver's compartment and the gas tank early in 1967. Any car raced during 1967 had to have the bulkhead replacing the fiberglass spare tire mount.
The 16 Group 2 Mustangs were painted white with black interiors. All cars were sold to independent teams. Shelby did not run a Group 2 Trans-Am team in 1966. Only one car was completed in time for the Trans-Am race at Sebring in 1966. Three were to be available. The first car went to Cooper, Clark & Associates. They paid $6,414 for the first Group 2 car in a bidding war. Later Group 2 Mustang sold for $5,500.
Shelby prepared cars placed in five out the remaining six races. Independent teams drove non-Shelby Group 2 Mustangs to wins at Mid-America Raceway, the Virginia 400 and second at Briar 250. Ford and Chrysler fought for the lead in points up to the last two races. At Green Valley, Brad Booker and John McComb driving a Shelby Group 2 Mustang beat out the "Team Starfish" Barracudas and Group 44 Dodge Darts to win tying the standings at 37 each for Chrysler and Ford.
The last race of the season was at the Riverside Track in California. Shelby sent Jerry Titus to drive a Shelby Group 2 Mustang. During the qualifying on Saturday Titus set a track lap record of 1:41.9 at an average of 91.854 miles per hour to earn the number one spot for the race on Sunday. The race started with a LeMans type start. Titus flooded his Mustang leaving him next to last to start. A later broken oil filter cost him almost two laps while it was being replaced. Titus fought his way through the 34 cars to finish first, 48 seconds ahead of the Tullis Group 44 Dodge Dart. Mustang and Ford won the first Trans-Am Manufacturers Trophy.
Source of information: SAAC Shelby American, issue #50 from an article written by Bill Hanlon
After winning the Manufacturers Trophy in 1966 & 1967, the Ford team had some stronger competition for 1968. Chevrolet was about to get involved in a very big way. Vince Piggins at Chevrolet saw the great potential for sales of Camaros by racing in the Trans Am series. He committed to SCCA that Chevrolet would support the series.
Piggins personally took charge of the Z-28 project. The first Z-28s were powered with the proven 283 cid. Chevy's production engine was a 327, but it exceed the maximum displacement allowed at 305 cid. Piggins came up with the idea of putting a 283 crank in a 327 block. The resulting 4x3 bore and stoke yielded 302.4 cid, a 13 cid advantage over the Ford 289, as much as 25 horse power. It took more than cubic inches to beat the experienced Ford team. Penske was enlisted to champion the Z-28 Camaros. The Z-28s won the last two races of the 67 season.
The 302 Camaros had a clear horse power advantage over the Mustangs. The ports and valves in the 289 heads were too small to produce the horsepower needed. The best head available was the hipo heads with small valves and ports. The new Ford 302 would be ideal for Trans-Am racing since it under the 305 cid limit of class limit, but the hipo heads would be even more restrictive on the longer stoke of the 302. Ford started a crash development program to fix the problem at Ford Engine and Development during 1967. This effort would lead to development of the Boss 302 in 1969. It was also during this development time that the famous Ford "tunnel port head" came about. There was a pull out the stops effort to maximize the flow of the heads. The Ford engineers developed a brand new head with straight intake ports and the pushrod tubes running through the port. In the past the ports would twist around the pushrods. The intake valves were a huge 2.12" compared to 1.77" for the 289. The exhaust valves were 1.54" versus 1.44". Each port feed an individual cylinder. These heads became known as "tunnel ports." On paper this combination of the head design with the new 4 bolt main 302, looked unbeatable.
Ford dropped the "Terlingua Racing Team" image and provided full support to the Shelby Racing Company. Two Group 2 Mustangs were built for the Shelby team.
The first Trans-Am race was the Daytona 24 hour endurance race. This was the first time that the Trans-Am cars were included in the primary event. Trans-Am races were held prior to the main endurance races in 1967. The Mustangs dominated the Group 2 race. Jerry Titus and Ronnie Bucknam 64 laps ahead of the nearest Group 2 car, Donohue's Penske Camaro. In fact, the Titus/Bucknam Mustang finished third overall just behind three Porsche 907 prototypes. It was a great showing for Ford, the Shelby Team and the Trans-Am cars. Half of the 30 cars that finished the race were Trans-Am cars. But Daytona wasn't the beginning of Ford's 1968 success, it was the end.
You have to finish races to win them, though. The tunnel port engines just didn't have lasting power. Engine failure after engine failure keep the Mustangs from finishing the races. Penske's Camaros dominated the 1968 Trans-Am racing. Mark Donahue, driving a Z-28 won eight consecutive Trans-Am races, beginning with the second race, the 12 Hours of Sebring late in March 1968. Donahue actually won a total of 10 out of 13 races in the series. As for the Shelby's team, the only races they won were the 24 Hours of Daytona in February, 1968, and Horst Kwech won at Riverside in car #17 in the next to last race of the season. The Manufacturers Trophy was already sowed up by Chevrolet.
The eventual blame for the Mustang's poor showing was the laid on the "tunnel port" engines. The engine has a bad oiling problem at the top end of the rpms. Many engine came apart during the season. The Shelby Team even asked Ford to let them go back to the tried 289's but Ford wanted the 302's to win. Which they didn't. The "tunnel port" quickly faded away after the 1968 season. The Donohue Camaro was awesome on the track. The Penske team got more horsepower from the Chevy 302 then the Mustangs and flat outran them. As the season matured so did the Camaro team. But with the Ford team's bad luck, it didn't take much effort to win the season. Chevrolet finished the season with 105 points to Ford's 63.
Before the '68 season was over, Ford was already working on a new block design, the 351, for the 1970 production runs. The 351 heads had huge canted intake and exhaust valves and ports. Someone decided to try those heads on the 302 block. With some slight modifications to water passages, the heads fit on the tunnel port block.
During 1968 SCCA opened up some of the rules. The cars could have floating rear ends, four wheel disc brakes and wider tires. Wheel and fender flares could be added to accommodate the eight inch tries. Fuels cells were mandatory.
The back ground picture is a 1966 Group 2 Mustang being driven by Jerry Titus.