Ford’s incredible 1969-70 Trans Am BOSS 302. Not the 2012-13 Coyote DOHC BOSS, but instead the genuine pushrod original from an era when Ford did the unthinkable repeatedly—and won! Ford’s classic 1969-70 BOSS 302 engine was a bold step forward after a miserable season in 1968.
The odds of you building a vintage Ford BOSS 302 engine are slim because Ford built so few and so many are already spoken for. However, it’s always fun to think about building one or even erecting one from scratch, which you can do with a Ford Performance BOSS block (M-6010-BOSS302) and Cleveland heads. You may also cruise the online auctions for a vintage 5.0L roller block (F1AZ-6010-B). There are plenty of them lying around used and new-old-stock.
Ford has always been a car company that dared to go where no automaker had ever gone before. That tradition dates back to the company’s founding in 1903. Think of Ford as a free-spirited car company with a rich history, driven by ego, that took big risks much as it is doing today with electric vehicles.
In the 1960s, Ford was an outspoken car company, much as Pontiac Division was within General Motors. Pontiac was the outlaw division. It didn’t conform to corporate protocol and invented the muscle car in its 1964 GTO. It had to sneak the GTO in under the radar of upper management. Ford took on the world with the GT40 supercar. Ford went to Le Mans and beat Ferrari not once, but four times, settling an age-old dispute over who had had the fastest cars in the world. Henry Ford II wasn’t going to have it any other way. Enzo Ferrari, and others, were handed their backsides.
Ford’s great success with its powerful V8 engines is legendary. The brute 427 FE Series big block that won Le Mans also reigned supreme in limited production 1964 Thunderbolt Fairlanes in NHRA competition. The darned thing was rabid dog fast. The 306-horse 289 cubic inch High Performance small-block V-8 in Shelby GT350s took on Corvette and the rest and managed to spank America’s sports car in SCCA competition.
With such great success under its seat belt, Ford decided to dabble with the 289 and stroked 302 to see what could be done to further its performance image. For the 1968 Trans Am season, Ford took the 302 cubic inch “Tunnel Port” out there in search of victory. Because the 302 Tunnel Port called for high revs in the 9,000 rpm range to make real power, racers scattered these engines all over racetracks across the country and left feeling defeated. The 1968 Trans Am season was a disaster.
Enter Ford’s development of an all-new 351ci engine with poly-angle valve heads and tight-fisted wedge heads destined for a 1970 introduction. Because the new 351 engine had the same bore spacing as the 289/302, it seemed logical for Ford to adapt this high-performance cylinder head to the small-block Ford V8. The 302 Tunnel Port already had a terrific four-bolt main block and steel crank along with beefed up “C3AE” 289 rods and special pistons designed for the Tunnel Port heads. Ford engineers took the new 351 cylinder head and modified it to work with the Tunnel Port block.
The result of this engineering effort was the BOSS 302 engine, which became the Trans Am mill of choice for 1969-70 and beyond in SCCA competition. To conceive the BOSS 302, Ford had to develop a special forged piston with a significant dome that would reach deep into the 351C head’s 64 – 67cc chambers. TRW developed these pistons and suppled Ford with them for both racing and production engines.
Because the BOSS 302’s heads sported monster-sized intake ports, these engines had a high-revving demeanor with peak torque and horsepower coming in around 7,000 rpm instead of the Tunnel Port’s outrageous nine grand. The result was a powerful 290-horse factory screamer with peak street power coming in around 6,000 rpm. These elements made the BOSS 302 a unique mill compared to what the rest of Detroit had to offer at the time.
We will admit to you our results on the dyno were disappointing—304 horsepower and 288 lb.-ft. of torque. We learned on the first few pulls that we had too much carburetor with our 750 cfm Holley 4160 and too little camshaft. Those of you who understand the BOSS 302 know Ford fitted these engines with a 780 cfm Holley but not necessarily because that’s what they needed. It was what the SCCA mandated for street homologation. Truth is, a factory original Boss 302 is happiest with a 600 to 650 cfm Holley. The BOSS 302’s biggest shortcoming is port sizing, which is something Ford has rarely been able to get right. The BOSS 302 engine could use better cylinder heads with right-size port and valve sizing in a set of Trick Flow cylinder heads and a more compatible roller mechanical camshaft. We tried this formula to see what our basically stock BOSS 302 would do. We got our answer.
Jim Smart is a veteran automotive journalist, technical editor, and historian with hundreds of how-to and feature articles to his credit. Jim's also an enthusiast, and has owned and restored many classic vehicles, including an impressive mix of vintage Ford Mustangs.