Championship Kart Racing Engines 

"McCulloch Special"

jimmy kart

This is an autographed picture Jim snail-mailed after we met at the 2004 VKA Vegas event.  The picture was taken in his backyard with a cinder block wall as his backdrop. The day we spoke about this webpage in August 2010 he was 84 years old and still owns the kart. We discussed some of the history behind the evolution of the engines on his kart and found it was difficult to remember some of the details. Until Jim and I review more of the history again you can be assured what you read below is as good as it gets. When your trying to remember what you did 52 years ago while you where just having fun can be a challenge. Building and racing for Jim was for fun, he just happened to work at the McCulloch plant in Los Angeles when the karting craze began.

jimmy saw with gearbox

Jim was employed by McCulloch to work in the "Special Test Lab" for new models. Before the launch of a new product and during development Jim was responsible for sheetmetal forming, welding, fabrication and testing before a product would go into production. He had all the skills and tools to heliarc (Jim says "heliarc" today we say "Tig) weld the twin alloy exhaust pipes with tubing from scrapped lawnmower handlebars. The engine block assembly is from a Super 55 chainsaw with what looks like to me is a center sparkplug head probably off a D44 along with it's center hole cover cut to make room for the exhaust. The gearbox is still in place with the addition of a sprocket on the gearbox output shaft to fit a larger roller chain than we use today. The larger size chain was used since he felt friction would be reduced with a roller style chain. I can only assume at this time the #35 roller chains, which are so common today didn't exist with roller links, so he used the size that came in a roller link style.
The intake manifold under the D44 airfilter cover is a standard 90 degree saw intake manifold with probably a S55 carb which eventually became standard on the MC10 kart engine.
I don't know why Jimmy used a D44 airfilter, but maybe we'll find out in the future. This is just a little example of  the many details you could ask which maybe don't matter to anyone anyways. But I find the evolution from chainsaw to kart engine interesting. For Jim it's difficult to remember what happened while he was karting 52 years ago! Jim prefers not to  guess or reveal information he's not sure about. So we'll probably need an other interview to see what else we can learn about the origins and evolution of the McCulloch Kart Engine. 

jimmy saw with gear box
Here's a new fuel tank fabricated by Jim using aluminum sheet heliarced together then topped off with a chainsaw gas cap. This must have provided the extra space to fabricate the intake manifold for the Amal carb Jim found in some of his or a friends motorcycle parts inventory. Jim also played around with motorcycles so he was able to use different parts like carbs and brakes off motorcycles on his kart.
Due to the float operation of the carb it didn't work well since karts corner so hard. The fuel would slosh over to one side of the fuel bowl on corners and starve the engine. Jim even tried mounting 2 Amal carbs and that didn't work either so eventually the chainsaw diaphragm carb was reinstalled. The exhaust is fabricated and heliarced from thin aluminum sheet and curved tight and close to the head then flared at the end. The engine is a Super 55 with it's standard side entry sparkplug cylinder head and hinged head cover.
Eventually Jim removed the gearbox in an effort to bring up the RPM's by eliminating  friction from the gears. He also used decided on a lighter/smaller chain to make more power gains. This is probably when power really skyrocketed and we pretty much know what happened next; the MC10 was introduced!

Jimmy Duel Engine Kart
Looks like two Super 55 chainsaw powerheads intsalled with original head shrouds and carbs.

Super 55 Chainsaw
In 1957 Jimmy was working in the McCulloch test lab preparing the Super 55 for new product launch. Jim must have been very familiar with it and had access to a variety of parts since he used them during the late 1950's.
In late 1959 or early 1960 it looks like Jimmy mounte two Mc10's from what we can see in the May 1960 Karting World.
McCulloch Special with MC10's in 1960 Jimmy in Karting World PDF

Production of the MC10 started in mid 1959 and from what I've determined from Jimmy's feedback he didn't have much to do with the introduction of the m10 probably since the markenting department set-up a whole new department for kart engine development.
That's about all I have on Jims kart for now. Next chance I get to work with him I'll add more to this section.
Please consider contacting me if you have any pictures or information on Jim and his karts/engines.
Email John T
 jimmy bug kart
Jimmy pictured here with my restored 1968 Bug Sprint at the 2004 Vegas VKA meet.

I found Wendell Shipman (Bug factory driver) wandering the pits at the 2007 Adams meet. Didn't really recognize him as he kept looking at my Bug, so I asked who he was and I remembered the name from old kart magazines/books. It was his first vintage event so I got him together with Jimmy and Duff when I shot this picture.
Wendell won the 100 mile Tecate race in 1961 on one engine! It's truly a great feeling to meet karters you only saw in magazines and books when you were just a kid!