OS Max-III and Stunt

I have an OS Max-III that I picked up in a swap. A cursory inspection showed a venturi that is far oversize for this engine in relation to the later Max-S 35.

Question - Is this engine timed so that if the appropriate venturi insert were fabricated and installed, it would run like a Max-S? Or, is this engine aggressively timed to run one way - flat out?

>Question - if the appropriate venturi insert were fabricated and
>installed, is this engine aggressively timed to run one way -
>flat out?
>
My best recollection is that the Max-II's and III's ran more like the majority of Torp GH's, rather than the 29-S or Max-S. They do stand up to the OS quality standards, and if I recall this right, had better con rods than the Max-S's (the major weak spot for the Max-S).

Quite a few Max-III's were used for Combat flying, but most were used in sport models. Set it on the rich end of its two-cycle, leaner than the four-cycle break point, and enjoy it.

The III is pretty much a one speed engine.

When in doubt, always choke the venturi down.

In '63, I had one on a combat model, and with Missle Mist, it was probably good for 110 mph or so. No way it would make a 4-2-4 stunt engine without a lot of rework. Pretty heavy, too. Steve

>The III is pretty much a
>one speed engine.
>
>When in doubt, always choke the
>venturi down.

I will probably do that to experiment with it. I was hoping that someone else had done it before and could tell me about it. Consenus seems to be that it is timed to run one speed.

Nicely made engine, though. Should be a lot of fun.

Although I don't use them on a regular basis, they are useful as fairly powerful sport engines. Use lower pitched props. Experiment with an 11-5 and even an 11-4.
They're pretty hot with a 10-6, speed wise. Currell