Vintage Overhead Valve Conversions for the Ford Flathead

But hot rodders are a resourceful bunch, and even before the factory overheads became a threat, they were repurposing and fabricating overhead conversions of their own to be fitted to the beloved flathead. The result: big power (for the time) and new records at the lakes. But there was a second, unintended consequence to these feats of engineering: they were absolutely beautiful. Check out the gallery below for evidence of this.

The Ardun is the best known of all the early overhead conversions. Developed by Zora Arkus-Duntov and his brother Yuri in the late 40’s. Zora would go on to great success at GM as the “Father of the Corvette” and author of the now legendary memo encouraging GM to do more to appeal to the burgeoning hot rod crazy “youth” market. But before he rose to fame, he created these heads to improve upon the flathead's relatively low power and tendency to overheat. They featured large ports and hemispherical combustion chambers (which reportedly had more than a little to do with the development of the Chrysler hemi) and claimed 175 horsepower on a stock Mercury flathead. But they really came into their own as record setting race heads in the hands of Clem TeBow and Don Clark at C-T Automotive. After serious work improving the valvetrain, they made 267 horsepower on alcohol and 303 horsepower on nitro. From there, the Ardun became a force to be reckoned with at Bonneville and the drags.

The Ardun remains famous today thanks to the efforts of Clark and TeBow as well as several hot rodders that have continued to develop them over the past 70 years. Sidney Allard used them in his famous J2 sports cars. Tom Senter wrote a series of “Ardun White Papers” that appeared in Rod & Custom in the early 70’s. The famous Ferguson racing family would continue to develop them to set Bonneville records. Ultimately, Don Ferguson Jr. would take over Don Orosco’s effort to reproduce them, making it possible for hot rodders to purchase a brand new set of Ardun heads.

Lee's Speed Shop in Oakland, CA was one of the first speed shops in the country, having been founded by Lee Chapel in the early 30's. Chapel created the Tornado OHV Conversion seen here. This engine also features a Lee Chapel custom made intake manifold.

This engine ran at the August 1950 Bonneville Speed meet in a streamliner sponsored by Lee's Speed shop. It reached 175 mph and set a record for OHV V-8 engines, but was not the fastest on the flats. The Tornado ran at Bonneville with a 180-degree crankshaft also.

These heads were built by Rudy Moller and Kenny Adams and used a hemispherical combustion chamber that was similar to the Ardun, but used some complex rocker geometry to make it happen. In spite of the Rube Goldberg nature of this setup, they were very successful, especially in the hands of flathead masters Clem TeBow and Don Clark at C-T Automotive (see above for more on their work with the Ardun). They built the very engine you see here using these heads and a sophisticated slide-valve injector to run Bonneville. On a load of nitro, this engine made 320 horsepower and ran 229.77 mph in the Hill-Davis City of Burbank streamliner in 1952, breaking a record held since the 30’s by Germany’s Auto Union.

This wild DOHC design was developed by Joe Davies and a pair of these heads appeared at Indy in the Bob Estes Special in ’51, having been run the previous year with an Ardun flathead. Later versions were driven by a belt, but those pictured here are the earlier shaft drive versions.

These cast-iron heads were built by “Colonel” Alexander before WWII. These heads were of an “F-head” design, which relied on the stock flathead intake passages and moved only the exhaust valves and ports out of the block. This helped to rectify the age-old flathead heating issue caused by the exhaust passages winding through the block and its water passages, but didn’t do a whole lot to help actual airflow.

These heads were developed for the early 21 stud blocks and were surprisingly sophisticated, featuring four intake and four exhaust ports (unlike other contemporary designs like the Alexander which forced multiple cylinders to share an exhaust port). Early versions reportedly had the intake coming in on the outside of the head. Later versions (like those featured here) used adapters to allow for a stock-style flathead intake manifold.

These imposing looking heads were reportedly built in the 50’s for a Pike’s Peak entry and resemble a big cast-iron version of the Ardun head. Only 3-4 sets are known to exist.