Hi,
I bought a used Cherokee twin engine plane at a yard sale. The plane is pretty much usless, but the engine seemed fine. It is an OS 46 SF, barely looks as if it has been run. Apparently the old owner reversed one of the engines so he could counter rotate the props on his twin. How, if at all possible, can I reverse whatever he did and make this a forward running engine? If not, would a reverse 46 SF bring good cash, or would it be better to fix it to where it runs in the correct direction. Thanks as always for your time.

1965Comet

If the engine indeed has a reverse rotation shaft in it just purchase a left hand or pusher prop for it and go fly. That is how the engine was used in the first place. A pusher prop turned in reverse becomes a tractor prop.

Your best bet is to just go get a new crankshaft and then sell the reverse crankshaft. Props that turn the opposite rotation are hard to come by so your choice of sizes is more limited.

So you can buy a reversed crankshaft? Can anyone explain how this is possible, making the 2-stroke run backwards I mean?

Thanks!

The reverse crankshaft changes the timing on the engine. The timing is determined by the placement of the intake window or port. The intake port on the crankshaft is machined on the other side of the barrel of the crankshaft on the reverse crank. The threads for the prop are probably reverse also. It is basically a mirror image of the standard crankshaft.

If I remember correctly the SF has a two-piece case. Is the front housing turned 90 degrees from vertical as compared to the cyl.? If the previous owner used that method to reverse the rotation you could simply return the housing to normal. At least worth looking at. Take care, Cliff

Cliff
The SF has a one piece case.

the FSR series was a two-piece

Save it for your next twin project.