Ok I would like to know if anyone has drilled and taped this engine for a muffler, or what do you use strap on? I will be using it inverted on a pusher.

Tom

I have drilled/tapped Webra Speeds to accept the same mufflers/headers as an OS 60FSR. According to MACs Products an OS 50/61 FSR, ASP 61, Enya 60X, MVVS 61/77 header will fit.

Terry in LP

Quote:

ORIGINAL: frugalme

I have drilled/tapped Webra Speeds to accept the same mufflers/headers as an OS.60FSR. According to MACS Products an OS 50/61 FSR, ASP 61, Enya 60X, MVVS 61/77 header will fit.

Tom,


I guess your Webra Speed .61 is a rather early example, from the early '70s, that did not come originally drilled to accept a muffler and needed to be fitted with a strap-on muffler.

Later engines of this type have an exhaust stack pattern which is identical to MVVS .61-.91 engines and to the OS.61FSR.


This does mean a bolt-on arrangement (not bolt-through, like most current engines), with 35 mm between centers.


You can drill and tap your engine's exhaust stack, as Terry wrote, to accept an MVVS muffler.
Of all those engines mentioned, the MVVS .91 is the only one still in production and so are most of its mufflers.

They are most often much less costly than aftermarket items, despite being OEM.

Dar, I will check that out after a bit, MVVS mufflers are very light in weight and have a nice purry sound.

Dave,


The problem Tom has is that his engine does not have any exhaust stack bolt-holes yet...

In theory, any bolt-on muffler with the bolt spacing within reason (~34-38 mm), could have holes drilled and tapped in the engine to fit.



The MVVS/old OS/old ASP/old Enya size is just a comfortable 35 mm dimension, that would have enough 'meat' around it, for 3.5/4 mm threads to hold tight, in the engine's cylinder housing.

Dar, I made a little adapter for the MVVS 3255 muffler so he would not have to modify the phlanges for the Webra. My adapter is not real purty but works and does not leak. The prop you see is a Graupner 12.5x6 which the .61f turned at 11,300 rpm on Fox 5% nitro/20% Castor.

Dave,


So, the flange on the MVVS has the 'locator beams' above and below that tend to clash with the cylinder housing, or the exhaust stack itself of the Webra #1024...

This spacer you had fabricated seems to have easily solved the problem.

Thanks for the info,

I just got off Morris Hobbies, where I ordered the MVVS # 3255 it looks like this should work well; The adapter all so looks like it will work well!

Tom

Dar, I use that partiicular muffler on my OPS .60, the reliefs are to clear the cooling fins, they clear the cooling fins on the .61f using the adapter.

I recently ordered the MVVS 3255A from Pe. I followed Hobbsy's method of cutting an aluminum plate to adapt the Webra's exhaust port to the opening in the muffler. It's a great fit. Thanks for the help Hobbsy! I will run it this weekend and see how it performs.

David