A Look At Flathead Ford OHV Conversions With Speedway Motors

It is always great to see historic engines or cars doing what they were supposed to do, but you can’t count out the value of having a bevy of those super-rare and insanely-beautiful artifacts of a time-gone-by in one place and available for viewing. Museums are the caretakers of our past, and when it comes to early hot rod speed parts and engines, there is no place better suited for viewing than the Speedway Motors Museum of American Speed, based in Lincoln, Nebraska.

The flathead Ford engine has an entire room devoted to it. Notice all the intakes on the right wall and you’ll see how kind the aftermarket has been to this iconic engine.

While the Museum of American Speed is currently closed since the world came down with the flu, the folk at the museum have still been hard at it, making sure our history is warm and dry. They’ve also been sending out newsletters, such as the most recent one highlighting some of the various overhead-valve configurations of the iconic flathead Ford engine that call the museum home. At a time when everyone was seemingly on the same level and looking for that edge in making the current-day, hot rod engine of choice, faster than the next guy. And it all started with the flathead Ford V8.

(Left) This engine is a prototype of the flathead Ford engine that would be introduced in 1932. (Right) The flathead gets its name because the head is basically a "flat" piece of metal that covers the cylinders and valves contained in the block. (Photo Credit: Moefuzz at en.wikipedia.)

The fact men were racing horses against the new “horseless carriages” of the day just goes to show that wanting to go faster is not a contemporary mindset. In fact, Henry Ford has been quoted as saying, “If I had asked people what they wanted, they would have said faster horses.” While we have no evidence that he actually said those words, his summation of their desire could very well be true for the day. Car guys (and gals) race things. It’s what we do.

The flathead V8 soon became the darling of hot rodders and Veda Orr, who raced along with her husband Karl Orr, also helped promote hot rodding during the war with her California Timing News publications she sent to servicemen during the war.

When the flathead Ford came on the scene in 1932, it’s eight cylinders offered more power than the previous four- and six-cylinder engines, and originally, the engine focused on the truck and heavy-duty markets. It was there one of the flatty’s Achille’s Heels was realized. With the valves seated above the cylinder bores in the block, the intake ports had a much more direct shot entering the combustion chamber than the exhaust side, which needed to wrap around the bores to find the exhaust ports on the opposite side of the block. This meant that the two inner cylinders would need to share a port while the outer bores would enjoy their own. The exhaust gas’ up-and-over maneuver, coupled with a hot reach-around the cylinder gave heat plenty of time to work its way into the engine.

One of the biggest issues with the flathead was the exhaust ports weaving around the cylinder walls to exit on the opposite side of the engine. An OHV conversion shortened this path significantly.

With the heavy-duty versions being most susceptible to heat issues, the first attempts at separating exhaust heat were designed for the truck market. A perfect example of how incestuous the primordial automotive scene was during these early years is the fact one of the most revered hot rod parts for the flathead Ford was created by Zora Arkus-Duntov. Zora and his brother, Yuri, designed the Ardun heads in the late-40s, which bolted onto the flathead block, but re-positioned the valves into an over-head, hemispherical configuration. The exhaust then had a short trip out to the exhaust manifold, which reduced heat transfer greatly. Zora would soon find employment at Chevrolet, after penning his famous memo about the youth market and their passion for hot-rodding the Ford engine.

It wasn’t long before hot rodders founded a market for overhead conversions of the flathead Ford engine in the name of performance gains.

Hot rodders from every ilk soon found the Ardun heads beneficial for more than heat dissipation. Speed shops began working the heads for more flow and performance and soon, you found them competing in every form of competition. But, there were more than simply Ardun heads competing for the trophy, and this is where a stroll through places like the Speedway Motors Museum of American Racing can be a treasure-trove of information. They have a “room” completely devoted to the flathead Ford. Interestingly, part of that room is devoted to engines that went beyond the simple “flat-head” design and utilized many of the various “over-head conversion” units that were available. We thought it would make a great highlight for our RodAuthority.com readers.

 Ardun (The Popular Performer)

As mentioned, the Ardun heads are likely the most popular, and for good reason. They’ve been massaged by a long list of capable speed-merchants to great success and thanks to their resurgence in popularity, they are still available for anyone with enough coin to purchase a set. They take the sub-100hp flathead and have pushed it well over 300 horsepower! There was even a set of Ardun heads designed for the smaller V8-60 flathead Ford engine as well. Of course, these are even rarer than its big brother’s Ardun heads, but they are still well-represented at the Speedway Motors Museum of American Racing!

There was also a V8-60-sized version of the Ardun conversion which moved both valves into the head on a hemispherical combustion chamber.

Moller-Adams (High-tech flathead)

Clem TeBow and Don Clark at C-T Automotive had their hand in making the Ardun heads more favorable to hot rodders, but they also joined with Rudy Moller and Kenny Adams who built these more complex OHV conversion heads for the flatty. The Moller-Adams heads used a sophisticated rocker assembly, to which C-T Automotive added an equally-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 ’30s by Germany’s Auto Union.

Davies (The Steampunk Flatty)

A sophisticated gear drive system would morph into belt-driven camshafts in later versions of the Davies OHV conversions. Those valve covers would look right at home on the Indianapolis 500 speedway and doesn't look dated next to that Aurora IRL engine in the photo on the right!

With its four, gear-driven camshafts located above the over-head valves, the Davies OHV flathead conversion could easily win the Buck Rodgers Award for most futuristic appearing. Later versions were driven by a belt, but these are the earlier shaft-driven versions. 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.

Alexander (One Up, One Down)

As mentioned, there were two things to remember about this era – EVERYONE was trying something new, and heat was the flathead’s main enemy! The Alexander head was designed during World-War II and addressed the heat issue by moving the exhaust port up out of the block, but kept the stock intake port design. This reduced heat absorption but didn’t do much for performance, as the airflow’s path was still quite restrictive and convoluted. Looking at the exhaust ports, you’ll notice the Alexander design still makes the exhaust ports do double-duty between two cylinders.

Tornado (Speed parts from one of the firsts)

Lee Chapel founded Lee’s Speed Shop in Oakland, CA in the early ’30s and was one of the first speed shops in the country. Lee also created the Tornado OHV conversion and special intake for the 24-stud (1938-50 Ford and Mercury engines). This engine from the Speedway Motors Museum of American Speed also ran a 180-degree crankshaft at the August 1950 Bonneville Speed Meet in a streamliner sponsored by Lee’s Speed shop. The heads were marketed as putting 175 hp to a stock flathead with 250 horsepower on a bored and stroked racing engine.

Possibly one of the rarest OHV conversions is the Stephens. There are only 3-4 sets known to exist, and looking at the second photo, it's easy to see where Mopar might have gotten the idea for the Hemi engine.

While the first modifications to the flathead were not in the interest of performance, those very same components then helped to power flatheads well past what their creators had ever envisioned. Ironically, it was the design of the engine given to it by those who hadn’t dreamed far enough that eventually relegated the flathead to the history books. A performance-limited bottom end and larger, more easily modified overhead-valve variants soon took the lead on performance.

Other conversions include the Riley (Upper Right), which also had OHV conversions for Ford's four-cylinder engine, Simco (Upper Left), which was likely the most common OHV conversion since it was used in production vehicles in Europe, and the Cummings conversion (Bottom Photos). The Cummings OHV conversion used a shaft-mounted rocker assembly with four exhaust ports on each head and if you look closely, you can see all 16 plug wires that sorted spark to each of those spark plugs (two per cylinder).

The flathead Ford still enjoys a strong following and parts are readily available to rebuild one and keep that flathead-specific exhaust sound alive. While we are glad to have places like the Speedway Motors Museum of American Speed, where we can view a broad offering of these iconic engines, we’re also very thankful to the devoted group of individuals who keep these engines alive so we can not only view them but also experience them as they were intended. And, if we’re lucky, we may just get a glimpse of an over-head conversion in the process!

Article Sources

About the author

Andy Bolig

Andy has been intrigued by mechanical things all of his life and enjoys tinkering with cars of all makes and ages. Finding value in style points, he can appreciate cars of all power and performance levels. Andy is an avid railfan and gets his “high” by flying radio-controlled model airplanes when time permits. He keeps his feet firmly grounded by working on his two street rods and his supercharged C4 Corvette. Whether planes, trains, motorcycles, or automobiles, Andy has immersed himself in a world driven by internal combustion.
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