How a Ford dealer created the 428 Cobra Jet
It’s possible you’ve never heard of Tasca Ford, but the performance-oriented dealership certainly left a lasting impression on Ford—and the Mustang. In 1967, Bob Tasca Sr. combined race-proven engineering with factory Ford parts to create a high-performance Mustang supercar dubbed the KR-8. The Tasca-tuned combination worked so well that Ford pushed the engine into production Mustangs as the 428 Cobra Jet.
Although the original Ford Mustang was a hit with younger crowds from its inception, by ’67 there was competition in the pony car field. Chevrolet had shifted its performance focus away from the Corvair and onto the new Camaro. The Mustang underwent a restyle that brought a size and weight increase, and the engine bay was now able to accept larger V-8 engines between the shock towers. Ford offered its 390-cid FE-series 320-hp Thunderbird Special V-8 for 1967, but there was a problem. Performance.
The 390 might have been acceptable in a personal luxury Thunderbird or full-size station wagon, but under the Mustang’s hood it was no match for a Camaro packing a high-winding, deep-breathing 327-cid small block V-8. And it certainly wasn’t enough against the Pontiac GTO or big-block Plymouth GTX. Word of its shortcoming quickly spread and sales lagged, prompting Rhode Island-based Tasca to come up with a performance fix for the heavy, low-revving 390 Mustang.
After tuning the 390 engine as far as it could go, Tasca turned to mechanic and drag racer Bill Gilbert for a solution that offered customers improved performance without costing too much. In theory, the high-performance Ford 427 V-8 could be had as a $622 option, but few young Mustang buyers were willing or able to fork over that kind of cash—the equivalent of $5,000 today—for a high-strung engine. Those who could usually opted for the Shelby Mustang. Gilbert came up with a formula that combined high-flow 427-sourced cylinder heads with a police-fleet tough 428-cid rotating assembly.
Noting that the 427-powered Galaxie got a considerable bump in performance from 1963 to ’64, Gilbert reached out to an engineering contact at Ford and determined that the performance increase was all due to changes in the cylinder heads. The bad news was that 427 cylinder heads would not fit the 390 block. In a stroke of genius, Tasca ordered a factory stock 428 Police Interceptor short-block assembly from Ford and discovered through creative fitting that the 427 heads would work on the 428 short-block with little more than piston notching for larger valves. “I flycut the pistons right in the block,” Gilbert said.
He sorted out camshaft specs and placed a call to another insider at Ford—Poppa “Sully” Sullivan, who set up the machines and purpose ground a camshaft for the KR-8 combination that Tasca dubbed the C-Stock cam. The engine was equipped with a 427 oil pump and recurved 427 distributor, then topped with an aluminum dual-plane intake manifold and single Holley 735 CFM carburetor, fed by a dual-snorkel air cleaner. With a modified C-6 automatic transmission and suspension modifications, the formerly sleepy Mustang became the 7,000-rpm “King of the Road.”
Tasca used measured drag strip and real-world street testing over dynamometer-based tuning. “We didn’t have a dyno back then, but we had our own test called the ‘10-Second Test,’” Gilbert said. “It didn’t make any difference whether it was this car or that car or whatever car—you made the comparison test on that vehicle. Every time you did something to it, you’d run the 10-Second Test again. Was it faster or slower? That was our barometer.”
Tasca Jr. said the test began with a rolling start. “I’d go 20 miles per hour,” he said. “Bob Andreozzi would have the stopwatch, and as soon as I hit it, I’d count ‘8-9-10’ and look at the speedometer.” The KR-8 tested faster than baseline across the board.
Tasca Sr. drove the KR-8 from Rhode Island to Dearborn as proof of concept and for testing against some 427-powered factory specials. With a closed exhaust and street tires, the Tasca KR-8 ran a low 13-second quarter-mile at 105 miles per hour. Ford officials were so impressed they wouldn’t let the car head back to Rhode Island with the KR-8 powertrain. Tasca drove it home with a 427 from the Ford GT40 Le Mans program, backed by a Gilbert-modified C-6 transmission. After Ford dissected the KR-8 combination, Tasca answered any criticism of engine tolerances and piston-to-wall clearances by reminding the corporate guys that the 428 short block was a Ford factory part.
Additionally persuaded by thousands of impromptu inquiries about the 428 setup (Mustang fans simply tore out an article in Hot Rod magazine and mailed it), Ford Motor Company put the KR-8 engine into production. It was installed in the ‘68 Mustang as the 428 Cobra Jet. In a full-circle experience, Ford shipped Tasca Ford an early production selection of 10 Cobra Jet Mustangs in white. Bob Tasca asked Gilbert to weigh all 10 and chose the two lightest and best-running examples. One was converted by Holman-Moody into the 11-second Tasca Ford Cobra Jet Super Stock drag car; the other became the unbeatable “Street Bertha.”
Editor’s note: Bob Tasca Sr. died in 2010, but the Ford performance heritage that he set in motion endures today at Tasca Ford and the Tasca Mod Shop in Cranston, R.I. Special thanks to Bob Tasca Jr., who showed us around and introduced us to Bill Gilbert; Carl Tasca, who races a Ford Cobra Jet Mustang; and Bob Tasca III, who campaigns an NHRA Top Fuel Funny Car. The complete history of Tasca Ford can be found in “The Tasca Ford Legacy: Win on Sunday, Sell on Monday,” by Bob McClurg.