Unknown tube muffler.

[Perry Rose]

The muffler is custom built and has a bolt spacing of 1.500 inches. Rectangular opening. What engine has that bolt spacing? No markings on the muffler.

[John Park]

The muffler is custom built and has a bolt spacing of 1.500 inches. Rectangular opening. What engine has that bolt spacing? No markings on the muffler.

With a bolt spacing that wide, it sounds like it may not bolt directly onto the exhaust stack.  Remember how mufflers/silencers used to be mounted in the old days, with a strap round the crankcase and a couple of long screws?  Hardly any engine manufacturers supplied them - they were almost all proprietary items. (It was depressingly common for them to fall off during flight, I recall.)

[Dennis Adamisin]

Hi Perry

Brodak website shows the muffler for the Aviastar 53-61 with a spacing of 1.5".

https://brodak.com/engines/mufflers-1/tongue-muffler-for-aviastar-53-61.html

[Perry Rose]

Thanks Dennis, that must be what it's for.

[Air Ministry .]

aktly , the Super Tigre's pretty much 38 m.m. , which is 1 1/2 inch , in real money .