331CI, 680HP, '74 Jenkins Competition Pro Stock Small-Block Chevy
Don Wallace, Tampa Bay, FL
In the history of famous drag race cars, there are pivotal cars that changed drag racing technology forever. Big Daddy Don Garlits' rear-engined Top Fuel car comes to mind. Within the Pro Stock ranks, you cannot talk about innovation without acknowledging Bill "Grumpy" Jenkins. Jenkins Competition was best known in the late '60s and early '70s for Jenkins' ability to make amazing power with a small-block Chevy. He also had a reputation as a giant killer for slaying those powerful Hemi cars. While his '74 Pro Stock Vega, Grumpy's Toy XI, only won one race that year, it has since become one of the more famous cars of Grumpy's Toys. Don Wallace is the current owner following its recent restoration by Scott Hoerr.
What brings this story full circle is that Joe Tryson, Jenkins' original crew chief, built this engine back in the day. He just retired from Jack Roush in Charlotte, North Carolina, near Hoerr's shop, and since Tryson and Hoerr are friends, it only made sense that Tryson should assemble a 331-inch clone some 35 years later. In addition to the Vega, Wallace also owns Grumpy's '70 big-block Pro Stock Camaro as well as the Sox & Martin 'Cuda. Those two cars accounted for all the Pro Stock wins in that inaugural year of NHRA Pro Stock competition. Don also owns the '73 Bob Glidden Pro Stock Pinto that powered Glidden to his first Pro Stock championship. It's these little pieces of history that add a dose of clarity to today's performance world. Imagine racing in Pro Stock with production iron heads. It wasn't all that long ago.
A. Dry-Sump Hidden behind the water pump and electric water pump drive motor is the first application of a dry-sump oiling system in a drag race car. Jenkins employed a Weaver pump assembly, placing the tank at the rearmost portion of the engine compartment.
B. Ignition It's shocking to learn that even by 1974, Pro Stockers were still using dual-point ignition systems. Jenkins used a '62 Corvette cast-iron dual-point distributor even though the engine was spinning more than 9,000 rpm.
C. Drivetrain Games Grumpy's Toy XI was the first Jenkins car to run a Lenco four-speed planetary transmission. The previous car had attempted to run the lighter 12-bolt rearend assembly, but it was problematic, so Jenkins went back to the dependable Dana 60 rearend cogged with a stunning 6.17:1 rear gear. The rear suspension relied on a three-link while the rear tires were Firestone 14x32W slicks. Assuming the tires were growing 2 inches in diameter at 152 mph, that means this little small-block was pushing 9,300 rpm in the lights. Yeowzah!
D. Macpherson Strut This was the first Jenkins car built by SRD with the now-standard strut system designed via collaboration between SRD's Dick Whitman and Roger Lamb of Lamb Components. The struts allow more room for a gentler header tube radius away from the cylinder head.
E. Pressure Plumbing Jenkins used this separator to connect hoses on both valve covers. The hoses lead into the firewall where eventually they connect to a very early pan-evacuation system plumbed into the headers. The small, white, plastic pressure line leads to a vacuum gauge where Jenkins could monitor pan vacuum at speed.
F. Engine NHRA's Pro Stock rules in 1974 favored a compact car with a small engine, so Jenkins maintained his efforts with a 331ci small-block using the stock 3.25-inch 327 stroke crank and a 4.030-inch bore. Compression was pushed to the limit along with a mechanical roller camshaft. This was before the days of aftermarket aluminum heads and sheetmetal intakes, so Jenkins had AFR port a set of iron fuelie heads bolted to a massively modified Edelbrock tunnel-ram. He also traded those older center-squirter 660 carbs for a pair of 1050 Dominators. Jenkins says this engine made as much as 680 hp-that's 2.05 hp per cubic inch using factory iron castings. Try that today.
G. Radiator While plastic-tanked aluminum radiators are now commonplace on production cars, Grumpy's radiator was still copper brass in 1974.
H. Fuel Cooler This was back when almost all competition drag race engines used a Moroso fuel cooler. Inside this can was a coil of fuel line immersed in ice water to make the fuel denser. When was the last time you saw one of these?