46 LA tongue muffler

[Gary Alspaugh]

I have a LA 46 that I want to switch to a tongue muffler. Where is the best place on the muffler to drill for the pressure fitting?

[Bootlegger]

 Gary, if you put it at the back of the muffler, then it cab be used on a full fuse or profile model.
 When I say the back I am talking about the thin part of the muffler, if this makes sense to you..

[Don Chandler]

you might want to ask Tom Dixon that question.

[Brett Buck]

I have a LA 46 that I want to switch to a tongue muffler. Where is the best place on the muffler to drill for the pressure fitting?

   It doesn't make much, if any, difference. Depends on how you want to route it to the tank. I alway put the tap on the "top" (opposite the holes) because it was easy to hook up to the vent.

   Removing the stock muffler and using something else definitely puts you off the farm on the basic setup, and you will be on your own to figure it out. I saw a 46LA set up to run an 11-6 this weekend, and it seemed moderately OK, but certainly did not perform as well as a conventional system, and also needed a fine air filter and muffler pressure (the real muffler) to reliably draw fuel.

     Brett

[Randy Cuberly]

I have run many LA46's on tongue mufflers obtained from RSM.  I then found that drilling every other hole in the muffler to 3/32 diamenter improves the performance trememdously.  I use a I use a .284 diameter venturi with the OS FP needle valve assembly, or a .294 with a Aeroproducts Needle valve assembly (preferred).  This of course requires drilling the hole in the case and venturi out to .156".

In my opinion the LA46 performs at least as well this way as with the stock muffler and perhaps a little stronger in the mid-range.
I've flown this set-up for a many years both here in Tucson at 2300 ft and 100+degrees temps in 55 ounce airplanes, and also in California at close to sea level.  In Tucson I use 20% nitro in the summer and 15% in the cooler temps in winter (sometimes still fairly warm).  Here in Tucson I use the stock head gasket and in CA I usually add one .006 shim.

The photo below shows a Tongue Muffler with pressure tap on my G Nobler with Aero Tigre 36.  Works very well with this setup.

Randy Cuberly

[Scott Richlen]

Find an OS-35S muffler and use that.  It is much lighter.  Cut off the "stinger" tail-pipe.

[Gerald Arana]

Find an OS-35S muffler and use that.  It is much lighter.  Cut off the "stinger" tail-pipe.

Agggggggggggggggggggggg! NO! Don't ruin a perfectly good 762 muffler. 

That's what I use "STOCK" and it works fine for me. I also use a 6MM venture, OS NVA, 11X4 WOOD prop, 10 X 22 fuel and an extra head shim. (3-1/2 to 3-3/4 OZ's for the pattern)

But do whatever you want. I have enough engines/muffler to last me a life time and I don't have to worry about getting any more. But I will if the price is right! 

Jerry

[Perry Rose]

Try a Fox .35 muffler, bolts right on.

[Gerald Arana]

Try a Fox .35 muffler, bolts right on.

Right! And so does a RO muffler for the Fox 35. That is if Richard is still selling them.

Good luck, Jerry

[Rick Wetzel]

My experience is very similar to Randy Cuberly's. I've had good luck with the RSM tongue muffler and a DuBro pressure tap. I used some Loctite thread locker to hold the assembly together. My tap is on the side of the muffler opposite the exhaust holes. I would try Randy's suggestion about drilling out every other exhaust hole.

Tom Dixon reworked two of my LA .46's and both run well. I use an 11x5 BY&O prop and Powermaster GMA 10/22 fuel.

I set a DuBro plastic tank up for uniflow based on another post on this site. I need to run muffler pressure and uniflow or the engine won't run. I can get a pattern completed on 3.5 -3.75 oz. of fuel  without difficulty.

The stock muffler is probably fine if you don't mind the weight penalty vs. RSM's muffler. The stock muffler is also much quieter.

Rick