OS connecting rods

Hi Guys,

Well, Mikey is learning to fly inverted with the usual results. The Ringmaster is no more. Good thing I picked up an ARF Flite Streak at Tony's. I was checking the engine after the crash and noticed a lot of play in the rod, probably from a former life as an R/C powerplant. Where can I get a connecting rod for an older OS 25 baffled slug piston plain bearing engine? Does anybody make rods anymore? I can measure the old one and give dimensions.

On a related note there is an engine collecto this weekend and I'll be looking for more engines. Sometimes it is worth it to buy one with broken lugs or fins if the guts are good. Any hints on engine checking?

John, not PC in the PRC

Try to find Frank Bowmann, If I locate him I'll tell you.

He'a an excelent machinist.

In Christ,

>Try to find Frank Bowmann, If I locate him I'll tell you.
>
>He'a an excelent machinist.
>
>In Christ,
>
>Ion

Frank just registered on this forum as "Robinhood" (Bowman, Robinhood, get it?) Either find one of his posts or go to the profiles at the top to find him.

These rods are not made any more, and I don't know of anyone making aftermarket rods for anyone. To get them made you have to contract specifically and in in quantity, and know that you are going to sell that quantity. On these, probably not.

Your own suggestion of purchasing a used engine where the case is damaged but the insides are good is probably your best chance of finding one--or a modeler who has crashed one into the pavement, and lost a case and shaft, but where the rest of the engine is still good. Still, these rods, like the 35s, are a little big weak, so beware.

Oh, and remember that with any rod there is a degree of "slop" at top dead center and bottom dead center. Check it in the middle of the stroke to find out whether or not it really needs replacing

My LHS here in Huntsville, AL had some older OS engine parts in stock. I bought all their .35 and .40 FP head gaskets and they ordered more. So the parts just may be in a bin out there and only way to tell is ask at the LHS or any OS dealer. They get their stuff from Tower Hobbies or Great Planes I believe.

I made a new connecting rod for a McCoy 35 last winter in the machine shop we have at work. I told my friend about it and he said, Why did you go to all the trouble to make a new rod I could have fixed it in 5 minutes. I said, OK tell me how. He said, Lay the rod on a piece of steel and hit it with a hammer hard enough to smash the metal and cave in the crank shaft hole. Then run a reamer through the hole to make the hole the correct size again. I tried it with another old engine and it worked. I put the engine on and airplane and its doing great. This might not be the best thing to do but it seems to work.

Making a new rod is not very hard it just takes time. Any machine shop near you can make you a rod. Shop rate is about $50.00 to $75.00 an hour so it may be cheaper to buy a new engine.

I think you could probably hit the rod with a hammer just hard enough to smash in the hole a tiny bit then put it on the crank shaft to see how much tighter it is. If its not tight enough hit it again and again until it fits tight. Then you would not need a reamer to resize the hole. This hammer mechanic fix might not work with a good quality engine.

Be sure to get some demensions off the rod and draw a picture of it before you destroy it with a hammer. A machine shop will need the old rod and the engine to make a new rod.

I can make rods. No problem. It takes about an hour to make one rod at a time. Set up is the slow part. I could probably make 10 rods at a time and have only about 15 minutes work in each rod. A local machine shop can do the same thing.

It might be better to squeeze the rod in a press or vise to close it.