Old OS Engine

Looking through old stuff (retreads have lots of old stuff)I found a somewhat gummy .35 OS CL engine. I don't know much about it, but it has a baffled piston, and a steel sleeve with fins that sits on top of the case with two of the six head bolts holding it down. It weighs less than 210 grams. Does anyone know what it is, how suitable is it for what type of airplanes, and does anyone still have gaskets or mufflers for it.

On the side of the engine what dose it say? MAX-S or III. Gaskets can be made. Eather engine is a good one. Stronger then a Fox-35 good 4-2-4 break. It will fly any of the planes up to 600sq and under 44 oz.

Scott(Like them old OS engines)Riese

It is probably a Mark III or I with the steel fins. As Scott says, it is a good stunt engine. Mufflers can be a problem. I don't know if the "Dustbin" mufflers I have will fit, but you could try one. They work nice on profiles if it fits.

Leonard Neumann

>It is probably a Mark III or I with the steel
>fins. As Scott says, it is a good stunt engine.

The two Marks named above are both identified that way on the bypass side; it will say either "Max-I" or "Max-III" there. If it has a single exhaust, steel fins, a larger trumpet intake, and no Mark number on the bypass, it is likely to be the Max-II model.

In my experience, the OS engines pre- "Max-S" or "Max-H" weren't usually willing to run the classic 4-2-4 breaking stunt run, but were quite powerful. Somewhat the way I think of the Max-S's as "improved Fox Stunt Motors", I thought of the Max I, II, & III as improved Torp Greenheads. None of my old Greenheads ran the 4-2-4 (I didn't have a 29S until recently), and I thought that the steel fin Maxes were similar in that regard.

GMA told me several times that there were GH 35's that ran a very nice 4-2-4, but I had a half dozen of my own during 1954/57 that never were willing to do so, which makes me think today that the ones that would do so may have been later in the GH production run than the ones I had.

>>It is probably a Mark III or I with the steel
>>fins. As Scott says, it is a good stunt engine.
>
>The two Marks named above are
>both identified that way on
>the bypass side; it will
>say either "Max-I" or "Max-III"
>there. If it has
>a single exhaust, steel fins,
>a larger trumpet intake, and
>no Mark number on the
>bypass, it is likely to
>be the Max-II model.
>
>In my experience, the OS engines
>pre- "Max-S" or "Max-H" weren't
>usually willing to run the
>classic 4-2-4 breaking stunt run,
>but were quite powerful.
>Somewhat the way I think
>of the Max-S's as "improved
>Fox Stunt Motors", I thought
>of the Max I, II,
>& III as improved Torp
>Greenheads. None of my
>old Greenheads ran the 4-2-4
>(I didn't have a 29S
>until recently), and I thought
>that the steel fin Maxes
>were similar in that regard.
>
>
>GMA told me several times that
>there were GH 35's that
>ran a very nice 4-2-4,
>but I had a half
>dozen of my own during
>1954/57 that never were willing
>to do so, which makes
>me think today that the
>ones that would do so
>may have been later in
>the GH production run than
>the ones I had.
>
>
>Kiwi
>
>

Agree. Steel Fin OS vs Greenhead is a good analogy.

Remember when either of these engines were used dead stock in combat before the first round venturi Fox Combat Specials came out? And I'm not talking about the .35C Greenhead either, necessarily.

As kids, we would argue the greater higher rpm-achieved power of the Torps vs. the steady, somewhat more appropriate, flatter torque curve power of the Fox. (Although we hardly phrased it as such then).

One might be able to goof around with a Greenhead (another head gasket, play with props, a little less venturi?) and get it to 4 some.

Or maybe not. The .29S Torp is, however, fairly Fox like. It surely goes through fuel fast, though. I have one on a Buster.

Currell

I will have to pull it out of the crook pot tonight to see, but I think it had 35 in a circle on the left side with OS written over. The head fins are very short, and it has an rolled insert in the venturi. I would guess that this is a 10-6 or 10-6W engine, or? Parden my Rev-up bias, as I worked for Chris part time while in college.

It has been said before but Playing cards make a good gasket material and soda cans with the finish sanded off make good head gaskets.