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Apache with Super 55s - by Dan Erickson |
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The building of the Apache was the most fun I've ever had doing a vintage kart. I had rounded up several old Mac Super 55s over the years in anticipation of
installing them on an early frame. When I came across this 1960 Apache in the local free ad paper, I had my combination. (The fact that my first kart at age 12 was a '60 Apache made it even better!). |
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I've always thought one of the things that made early karting so cool was that every builder had to come up with his own designs- there was no factory
stuff. How to mount a Zundapp, setting up a Koenig, every kart showed it's owner's ingenuity. I don't think anyone ever tried to mount Mac chainsaw motors on an Apache, so I tried to approach it the way someone in 1960
would. I completely rebuilt the Super 55s, using mac 49 thin ring pistons, making my own gaskets and sourcing the seals at NAPA. I smoothed out the intake passages, and replaced the tiny stock HL-15s with larger
Tillotsons from a Stihl saw. I've always admired the look of the stock gas tank and 3 hole air intake on the 55s, so I rigged up a throttle setup that goes THROUGH the tank to the throttle shaft so the clean lines don't
get messed up with cables. |
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The most challenging part was figuring out a drive and mounting setup. I looked through a bunch of old Quarter Midget World magazines and the old
Trend karting books for ideas, but every kart was different (of course) and none really showed how they mounted the saw motors. I figured the logical mounting point would be where the tubular saw handle bolted to the
gearbox, so I mounted the 2 saws to a 1" shaft riding in 2 pillow block bearings. Then I tied them together with a length of 3/8 shafting with plates welded on the ends bolted to the holes for the old chain bars.
On this shaft I put 2 Heim joints attached to a RH/LH turnbuckle attached to another Heim. With this setup I could mount the pillow block bearings to plates I welded on the kart- this would provide the main support for
the motors, then I could attach the free Heims to a shaft mounted on the chassis. This way the motors would pivot on the 1" shaft, and the chain tension could be set by turning the turnbuckles. The engines are
semi- Siamesed in that the output shafts are tied together to a common shaft and sprocket, but each engine has it's own centrifugal clutch in the gearbox bathed in 140 wt oil. I guess I'm REAR legal- I'm running oil
clutches but no expansion chambers :) I found a couple of stainless cones and had a shop put a 90 degree bend in some 1.5 inch tubing and welded up a couple of mean looking megaphones for the exhaust ( a real sweet
sound). The motors run well, idle like a saw should , and are quite a bit faster than I expected, but they have a TON of compression that makes them a real bear to start ( not to mention the strain on 48 year old
starter pawls) |
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I sanded down and polished a set of Hands wheels, mounted an old Cragar kart steering wheel that I have had since I was a kid, and that's about
it- took the kart for her maiden voyage at the get together in Riverside, and despite the admitted Rube Goldberg setup she ran pretty good! If anyone else is thinking about putting old saw motors on a kart, I'd be
happy to help in any way I can- I've got a lot of spares- It took 6 saws to make 2 good ones. Dan Erickson (
dartkart@mail.com) |
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More Photos - Click Here! |
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