Tongue Mufflers for Brodak B-40

[bruce malm]

I have  quite a few of the B-40's and they are great engines for the price. Note: all have been broken in with at least 20+ 2 minute runs. I also have 3 different style tongue mufflers. One has a lot narrower exhaust tube. All mufflers came thru Brodak. I recently finally took a new twister out
just to see how it would fly. It was slightly modified to my liking. Anyway I couldn't get a decent run out of it, so over the last few days I have been trying to figure out the problem including. change props, change plugs, remove tank and fuel lines to check for leaks, replace with another new B-40, open a new gallon of fuel, and replace the fuel tank. Finally I put on the stock muffler and everything seemed to click into place. I checked the quantity and size of the holes on the 3 different mufflers. the holes on the one I was using were a lot smaller and it appears was causing too much back pressure, plus the opening was smaller than the exaust port of the B-40. I used the trusty dremel to match the port and enlarged the holes in the muffler. I ran out of time so will have to test tonight. Also,
please note I have the exact same set-up, including engine, tank, muffler, and propellor on a Primary force that does not seem to have  quite the same problem. I will however, after testing, remove the muffler and make the same modifications to relieve the back pressure and what appears to be causing an over heating problem.

Hope this helps.

Bruce

[Bob Reeves]

I know Brodak offers 3 different tongue mufflers for the 40.. Would help to know which you are having the issue with..

[john e. holliday]

I would like to know also as I have a tongue muffler on its way from Brodaks.  DOC Holliday

[bruce malm]

Performed some more testing last night. The Brand Is the Aero Products CNC Tongue muffler.  It is a beautiful product and comes drilled for a pressure fitting and includes a pressure fitting. I have tongue mufflers from Aero for other engines and have not had any problems. I do not use pressure. I drilled out the holes to size that is on the Artimison tongue muffler and ran the engine. Same fuel, prop,etc and about the same outside temp. The enlarge holes improved the the situation but still seemed to cause some heating and increased needle valve sensitivity. I drilled another hole in the end of the muffler and it improved a little more. I will try the Artimison tonight. The Artimison is  a square design that uses long screws to attach to the engine and provide a lot more initial exhaust chamber volume. and I believe that is the problem with the other design.  I believe the size of  Aero muffler tube could be increased  during manufacturing and to solve the problem. I also have the other style tongue muffler that is similar in design to the Aero with a wider tube and of course more volume that I will test. Just don't remember the brand. I am using GMA 10/22 fuel just for everybody's information.

Bruce

[bruce malm]

Please be aware that these are my own experiences with the This particular muffler, on a Brodak B-40 using  a 10-5 propellor although I did try a 10x4 3 blade Grish and a cut down 12x4 to 11x4 Zinger during the original flying session. And I have NO desire to impune the reputation of Aero Products or the use of this muffler on any other engines. This has been only my eperinece in trying to solve a problem with this set-up and wanting to help fellow modelers

Thank You,
Bruce

[RandySmith]

Performed some more testing last night. The Brand Is the Aero Products CNC Tongue muffler.  It is a beautiful product and comes drilled for a pressure fitting and includes a pressure fitting. I have tongue mufflers from Aero for other engines and have not had any problems. I do not use pressure. I drilled out the holes to size that is on the Artimison tongue muffler and ran the engine. Same fuel, prop,etc and about the same outside temp. The enlarge holes improved the the situation but still seemed to cause some heating and increased needle valve sensitivity. I drilled another hole in the end of the muffler and it improved a little more. I will try the Artimison tonight. The Artimison is  a square design that uses long screws to attach to the engine and provide a lot more initial exhaust chamber volume. and I believe that is the problem with the other design.  I believe the size of  Aero muffler tube could be increased  during manufacturing and to solve the problem. I also have the other style tongue muffler that is similar in design to the Aero with a wider tube and of course more volume that I will test. Just don't remember the brand. I am using GMA 10/22 fuel just for everybody's information.

Bruce

Hello  Bruce

Over two hundred of these are  already out there in use, I did not have any problems with them here in my test, and this is the first  time I have heard anyone  complain.
Also as with any tongue muffler the holes are NOT open to maximum size, they can and  are  routinly  drilled  larger to match the requirement of the user....IE  some planes run the motor hotter than others, and  some  use  less  oil than others.
This muffler is  also used on the HP 40 and  the  FOX 40s, again  I ran them on both and  had  no  sensitive  needle  problem.
It may be  with your  setup that the muffler needs to be opened up and \ or you can use more oil in the fuel.  This is  a  normal thing to do when using a tongue  muffler, as they are  ALL more  restricted  than tube  mufflers

Regards
Randy

[bruce malm]

Thank you Randy,
and that is what I believed! That is why I put in the disclaimer. The entire purpose was to help other modelers  that might run into this particular problem.

I have a lot of your products and you provide a fantastic line of products.

Respectfully,
Bruce Malm

[Bob Reeves]

Good info by both Randy and Bruce..  Finishing up a Ringmaster for OT that is going to run a Brodak 40 with tongue muffler. The whole package RTF should come in at 26 ounces. Know it doesn't need that much engine but thought it would be fun to let the 40 loaf through the OT pattern.  Have always ran the stock muffler on my B 40's and the timing of this thread is perfect..

[john e. holliday]

Got my new Brodak tongue muffler today and immediately went to the basement to mount it.  The mounting holes were a little too close together to get the screw started.  I mean all I did was remove the stock muffler and try to put on the new one.  I ran a drill bit thru the holes to enlarge them just a scosh.  Sure changes the looks of the nose of the Oriental.  Mine is listed as the Adimisin version.  Hope to try it this week.  Also thanks for all the pictures from the Brodak get together.   DOC Holliday

[bruce malm]

Performed more testing last night and this will be my final post on this subject.
Please let me state that this engine is on a profile type airplane and the tanks used are 4 oz. metal plummed in 2 different configurations for uniflow and several different style and heat ranges of glowplugs. I continued testing both the Adimson, the Aero, and the other brand. Some worked better than the others but they all made the needle valve more critical and unstable. Note: These engines have very little running time past the recommended break-in period. Even the difference in tank venting had a very noticeable effect. The last run was to install the stock Brodak muffler. The engine then became very easy to adjust and the engine setting very stable.  ALL these tests were performed on the ground. 
I personally plan on flying all new B-40'S with the stock muffler  to set a baseline and then  when I am convinced the engine has enough running time install the different mufflers to see how they effect the performance and criticality of the needle setting.

Hope this might have helped a few. As I said, I had NO intention of demeaning any product and the information about drilling out the holes, as a normal procedure, from Randy, has enlightened me and will be useful when I have to solve any future problems.

Respectfully,
Bruce Malm