The Jack Henry dual manifold was advertised in early issues of Hot Rod. Rather than cast h
Morrison's now-rare "Duo-Dual" was a side-by-side unit with the carburetors mounted on two adjacent risers. So were the intake designs of Jack Davies and Alexander. They're highly prized today. Most early intakes used the high-rise configuration ostensibly so there was ample clearance for the generator. Thickstun's tall PM-7, Eddie Meyer's beautiful exhaust-heated unit, (he made a water-heated manifold too), and Vic Edelbrock's famed "Slingshot" designs soon proved popular. Low-rise intakes by many of the aforementioned makers, plus newcomers like Navarro, Burns, Schultz, Fenton, Offenhauser, Freiman, Clark, and Lightning, to name a few, soon appeared. Interestingly, while the low-rise style was thought to be more suitable for racing, later dyno tests showed that some high-rise manifolds actually provided a mild ram intake effect that was more efficient.
Navarro, Vic Edelbrock Sr., Iskenderian, Charles "Kong" Jackson, Weiand, the Spaulding brothers, Evans, and others dove right into the fledgling speed equipment business. And most of them concentrated on hop-up equipment for the popular Ford Flathead. Racing, at the dry lakes and later at Bonneville and the drags, was the crucible; if your car won, people flocked to you and bought your equipment.
This full-race fuel-injection system for a Ford Flathead is an early Hilborn-Travers setup
As a collector of vintage Ford speed equipment, I once asked (the late) Navarro why there were so many different manifold, ignition, and camshaft designs. "Following a sheep won't give you success," he said wisely. "You have to go down a different path than the rest. When you do that, you've got to learn what the rest don't know."
When World War II ended, anticipating a career as a civilian, Navarro realized he knew more about machine work and hot rods than anything else. Before he was discharged from the Army Air Force, he designed his own dual manifold, loosely based on the stocker on his '42 Ford, a car he'd bought seven days before the attack on Pearl Harbor. Barney's first 2x2, a low-rise affair with a "dog bone" shaped removable heat riser, resulted from an experience he'd had crossing the mountains in New Mexico in winter, using the tall, high-rise prewar Weiand manifold. Both carburetors had iced up and his car slowed to 35 mph, painfully strangling itself.
Here's a GMC 4-71 blower that's been "pruned" (the original fins have been trimmed so the
Navarro decided to improve on that design. "Remember," he told me, "the firing order on a Flathead alters from bank to bank, except for cylinders one and two, which fire sequentially. Every time it fires you have exhaust on one side or the other, so it (my design) kept the carburetors warm. For summer use, you simply took out the long center stud and replaced the dog bone with a little finned cover. Unfortunately for Navarro, it wasn't very popular (though it's a $750-plus collectors' item today if you're lucky enough to find one, especially if the original "dog bone" attachment is intact). "People thought an absolutely cold charge gave maximum horsepower; later I built a manifold with the heat riser underneath.
"In those days," Navarro said, "most equipment was sold by speed shops and very little was sold by mail order. It's the other way around now. In the '50s, Alex Xydias and Ray Brown sold my equipment, as did many others."
In his era, most competitors didn't do much theorizing in writing. Navarro, whose nickname was "The Professor," charitably opined that most of them didn't have the requisite educational background. "They really didn't understand the principles," he says. "Some of those early manifolds (the ones that we collectors cherish today) really didn't work."
Ford factory engineers understood how to maximize the Flatty's 180-degree firing order and effectively harness their engine's firing impulses. Navarro's first really successful manifolds were built on those principles rather than trying entirely new manifold configurations like many less successful rivals. He further improved the dual, and later, his triple intake's plenum chamber, to maximize mixture flow.
Cheap thrills: Over a dozen manufacturers offered these $10-15 two-into-one manifolds. Loo
Racer and rodder, Owen Betry, ran a garage in Glendale, CA. This rare, cast-iron 2x2 manif
I've never seen another like it. An earlier Betry effort (foreground) was a neat two-into-