Low-Buck Tech: The Flathead Engines of the 24 Hours of Lemons

By Staff Writer
Jul 5, 2021 | 24 Hours of Lemons | Posted in Features | From the April 2020 issue | Never miss an article

Story by Phil “Murilee Martin” Greden • Photography Courtesy the 24 Hours of Lemons

Many racers believe (incorrectly) that you need lots of fancy overhead cams on your engine to compete properly in road racing. Somewhat wiser racers prefer overhead-valve engines, with the cam located safely inside the block, but what about those complicated rockers and other failure-prone gadgetry bulking up the valve covers and generally adding unnecessary complexity? A half-dozen 24 Hours of Lemons teams know the score of the valve-location game, choosing to run good old flathead engines on the race track.

Otherwise known as an L-head or side-valve arrangement, a flathead engine contains all valvetrain hardware within the block, with the valves facing upward next to the tops of cylinders. A flathead’s cylinder head is just a simple slab of metal with holes for spark plugs.

The overwhelming majority of cars sold in America before the 1950s used flathead engines, and you could still buy flatheads in new Studebakers, Ramblers and Dodge trucks into the 1960s. Since wins in the slower classes of the 24 Hours of Lemons often come down to the speed at which teams can repair broken cars, a simpler engine should be a better engine.

We’ve seen a pair of racing machines compete with the rugged Chrysler flathead straight-six in the Lemons series, and those engines have held together very well for technology designed in the 1920s. The first was the 1950 Dodge pickup of Grumpy Cat Racing, which debuted at the Utah race in 2014. With the 218-cubic-inch six (rated at 97 horsepower when new) under the hood, the Grumpy Cat Dodge turned 560 full-throttle race miles at Miller Motorsports Park.

A couple of years later, Bad Decisions Racing threw its 1948 Plymouth sedan into the fray at GingerMan Raceway in Michigan, and its 218 flathead ran flawlessly all weekend long. Both these machines won the top prize of Lemons racing, the Index of Effluency, their first time out.

A side benefit of the Chrysler flathead-six is that huge numbers of these engines were employed in non-road-vehicle settings–things like irrigation pumps, generators, sawmills and airport tugs, which means teams have plenty of good-running replacement engines available at low prices. Grumpy Cat Racing bought an ex-TWA tug for scrap value and swapped its Chrysler flathead into the Dodge when the team’s original engine finally blew up.

The Hudson Super Six flathead engine stomped on the racing competition in the late 1940s and early 1950s, and a couple of Lemons teams have stepped up with Hudsons equipped with this engine. The ’52 Hornet of Chase Race had the twin-carb engine when it showed up at The Ridge Motorsports Park in Washington and probably should have been slapped with many penalty laps for going over budget. However, the wise and fair judges of the Lemons Supreme Court created a Hudson Super Six Loophole on the spot. A few years later, Sinical Racing dug up a basket-case ’50 Hudson Pacemaker and ran it with the Twin-H 308-cubic-inch flathead.

One of the most reliable flathead engines we’ve seen so far is the 75-horsepower “Lightning” straight-six flathead found in the 1952 Willys Aero-Lark of Four Yak Press Racing. With a three-on-the-tree manual transmission and slippy clutch, the Aero-Lark’s flathead engine never missed a beat at Sonoma Raceway, winning Index of Effluency glory for the team in 2016.

By far the most glorious flathead racing in the series is the straight-eight in the Escape Velocity Racing 1941 Oldsmobile 98. The team dragged this car out of a field, left the 70-year-old plug wires and almost everything else just as they’d found it, and turned 607 racing miles at MSR Houston with the 110-horse eight putting down its power through a Hydra-Matic four-speed automatic transmission and completely function-free lever shocks.

Is it time for a flathead Ford V8 in Lemons, preferably in a 1950s Simca Chambord? You bet!

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View comments on the GRM forums
iceracer MegaDork
6/12/20 12:42 p.m.

Right, they were so restricted that you could drive them flat out for a long time without hurting anything.

Ask me how I Know.

slowbird SuperDork
6/12/20 1:19 p.m.

I've been dreaming of a flathead Ford project recently. Probably because so many model cars came with them, in various forms.

Has a flathead ever appeared at the Challenge? If not, who is going to be the first? Where the heck can I find one for Challenge money?

I looked at them for the challenge. It would be do-able but I didn't see a way to make them competitive. 

jimbbski SuperDork
6/12/20 9:46 p.m.

When Bad Decisions acquired that '48 Plymouth since I had helped them with their earlier builds and did so with this one. Some day you may see that engine again at a Lemons race but in a different vehicle. The '48 currently sports a supercharged 3.8L Buick V6.

Some info on the Chrysler  flathead engine.  It was used in some versions of the Sherman tank of WWII.  The engine was called the "Chrysler Multibank".

Five I6 engines sharing a common crankcase. It made 450 HP and weighed nearly 5,000 lbs!  Most of the tanks so equipped were given to the British as the US Army had the radial engine version and knew that the Ford GAA V8 version was coming soon so it didn't want to complicate it parts & repair problems with still another tank engine.

YouTube link:  https://www.youtube.com/watch?v=4sUbtEE8I-g

NickD MegaDork
7/5/21 9:31 a.m.

The French military actually continued building brand-new Ford Flathead V8s, with some improvements like stronger blocks and a better oiling system, up into the '90s for use in generators and vehicles due to the reduced amount of parts to fail during continuous operation.

frenchyd UltimaDork
7/5/21 9:46 a.m.

In reply to NickD :

Not all flatheads came in American cars. 
my beloved Jaguar V12 is the true definition of a flat head. No combustion chamber in the head.  Not even a trace of one. 

Stampie GRM+ Memberand MegaDork
7/5/21 10:20 a.m.

In reply to frenchyd :

A flathead engine, also known as a sidevalve engine[1][2] or valve-in-block engine is an internal combustion engine with its poppet valves contained within the engine block, instead of in the cylinder head, as in an overhead valve engine.


NickD MegaDork
7/5/21 10:45 a.m.

In reply to frenchyd :

That's a "plank head", like a Chevy 348/309 or a GMC big V6 or a Ford MEL engine, not a flathead. A flathead has the valves in the block, with a slight combustion chamber and a pathway to feed from the valves to the cylinders.

Also, I wasn't saying that all flatheads were American. I was just saying that the French loved the Ford flathead design so much, that they reverse-engineered it from equipment that we left over there during WWII and then continued to build a near carbon coby some 40 years after Ford turned the last one out.

frenchyd UltimaDork
7/5/21 11:54 a.m.

In reply to NickD :

We can have a fun but worthless debate about what a true Flathead is.  But I'm reasonably sure a Chevy 348/409 has a combustion chamber in the head.  Let me see if I can find a picture of one. 
oK I found one and the valves are slightly recessed into the heads.  With a relief around them.  I guess I'll give you that.   

pres589 (djronnebaum)
pres589 (djronnebaum) UltimaDork
7/5/21 11:59 a.m.

This isn't really a debate, you just wanted to talk about Jaguar again.

frenchyd UltimaDork
7/5/21 12:06 p.m.

In reply to pres589 (djronnebaum) :and what do you know I learned something.  Americans call flatheads planked heads ( British call them Hurron heads)    And flatheads have combustion chambers  ( well,  I knew that)  

so flatheads aren't flat. Hurron heads are called planked. And we are all doing this for fun  


81cpcamaro Dork
7/5/21 1:09 p.m.

The overall height of a Flathead head is very short (2-3" or so ), especially compared to any overhead valve engine. They have a relatively flat appearance on the outside,especially when they are compared side by side to OHV engines. Most people never see the inside so why would you use combustion chamber as the name, except for the Hemi engines of course, and maybe a few others.

Tom1200 SuperDork
7/5/21 1:37 p.m.

Two Stroke.........the ultimate flat head engine.

7/5/21 2:12 p.m.

I always wanted to work on one. Now that I have, I am happy that I wont.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
7/5/21 8:13 p.m.
Tom1200 said:

Two Stroke.........the ultimate flat head engine.

Except for the ones with intake valves in the heads!


Trivia:  They used to experiment with putting cylinder ports in flathead Fords.  I'm still not all up on how that was supposed to work, but given how hard it was to find info about it, I'm assuming the answer is "not very well".

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