trying to find a muffler

[tom creasey]

I am asking all over that I am trying to locate a muffler for my OS MAX-H 40 eng. I think but not sure that the engine will on except band clamp style. You look in the port and there is bolt holes with threads in the holes. Myself I prefer bolts than a clamp. Thinking about buying a tongue muffler with clamp. I would like to have both so I have an option during test flights. My tank is uniflow pressurized or not....doesn't matter. I find that the OS MAX runs better for me if the tank is pressurized. To me it seems a better 4-2.   I am wanting used because I am on budget from the wife, think we can all relate....LOL.

[Bill Johnson]

Tom,
The OS #703 is the factory strap-on muffler. Unfortunately, they are somewhat tough to find. I have a couple H 40s but only one muffler. Keep an eye on Ebay as they do show up occasionally.

One of my winter projects is to make some strap on mufflers from Dubro muffler extension stock. I have 5 or 6 engines that need one and the old Dubro Muffl Aires are also hard to come by.

Good luck with your search!

[Avaiojet]

Tom,

I believe I have that 703 OS muffler, strap and all.

PM me if you still need one.

[tom creasey]

One of my winter projects is to make some strap on mufflers from Dubro muffler extension stock. I have 5 or 6 engines that need one and the old Dubro Muffl Aires are also hard to come by.

thank you for the info. I will do some research and look at the Dubro muffler extension. Do you know Dubro stock number?

[Robert Zambelli]

Tom: If you can post the exact center-to-center hole spacing in the exhaust port, we may be able to fit a Brodak tongue muffler.

  Bob Z.

[Bill Johnson]

thank you for the info. I will do some research and look at the Dubro muffler extension. Do you know Dubro stock number?

It looks like it's Dubro # 213, Tom.

http://shop.dubro.com/p/6-exhaust-extension-stock-qty-pkg-1

I bought 2 at a hobby shop in Pensacola 2 weeks ago for $6 each. The Dubro link is a little deceiving. All you get is the stock material. The Dubro add is showing you what you can make from it (the top of the picture with the short piece and the bolts).

I figure I'll cut a 2" piece, attach it with either a Enya muffler strap or a 5/16" wide hose clamp (much narrower then the typical 5/8" hose clamp), slap on an end cap made of 6061 aluminum, and drill enough holes in the top and/or bottom to match the engine exhaust area. Altogether, about $5 in material, 4 drilled and tapped 4-40 holes (2 for strap, 2 for end cap), and the actual exhaust holes.

I think that will work until I can get my shop (and drill press) set up and then I'll drill the crankcases for stock tongue mufflers.

[tom creasey]

Tom: If you can post the exact center-to-center hole spacing in the exhaust port, we may be able to fit a Brodak tongue muffler.

  Bob Z.
[/quote      

total O.D. of port in length is 1.544 inches (39.22 mm) and total O.D. height of port is .362 inches  (9.20mm). Do you want the tongue muffler to fit over the port right? On my OS MAX-H 40 the port do extend a little from the head

[Robert Zambelli]

Hi, Tom - the tongue muffler fits flat against the exhaust port, not over it.
When you look into the port, you should see two holes.
I need the center to center spacing of those holes.

  Bob Z.

[tom creasey]

Hi, Tom - the tongue muffler fits flat against the exhaust port, not over it.
When you look into the port, you should see two holes.
I need the center to center spacing of those holes.

  Bob Z.

Center to center is 1.302 inches

[tom creasey]

how is the tongue muffler designed with back pressure adjustment? Whats it look like inside?

[Robert Zambelli]

Hi, Tom.
Unfortunately, there are no Brodak mufflers that will fit your engine.
As far as I know, the only way to adjust back pressure in a tongue muffler is by enlarging or blocking off the holes.

 
Bob Z.