My engine does not fit, now what

[Steve Agrella]

I kind of figured since Iv'e been reading around that folks put OS 25 LA in a Ringmaster so I went and purchased one, the rails on the ringmaster are too darn wide, I might be able to angle the holes a bit to get it in there but the holes are right on the edge of the mounting rails.

Any suggestions.

[Allan Perret]

Make a "U" shape aluminum mounting plate from 1/8 thick stock.  Bolt engine to the plate, and plate to the plane.

[Paul Smith]

I've done this many times when swapping from a Fox 35 to an OS 25.

Wash the front of the plane with something that takes off oil, like denatured alcohol or even actone.

Redrill the old mounting holes and plug with dowels & epoxy.

Rough up the inside of the engine mounts with a Dremel and epoxy on some plywood shims.  Grind the the shims so the engine fits tight.  Redrill the holes to the new engine.
Fuel proof with epoxy finishing resin.

This works fine.  Not quite as good as doing it right the first time, but still a lot better than going to the grave with a Fox 35 Stunt.

[Will Davis]

I used one of the Brodak clamp mount systems on a retrofited  Firecat  from Fox 35 to la 25 ,Works great and a clean  installation , good for any engine I want to use   

[Dwayne]

I've never used Brodak clamp mounts but I've refitted many engines the same way Paul posted except I repaint the front of the plane it's easy but if you're in a hury use epoxy instead of repainting and you're flying the next day.

[Steve Helmick]

I would do what Allen P. suggested. It works very well. Use flathead screws countersunk into the plate, with washers and elastic lock nuts on the engine side. Use socket heads to bolt the plate to the fuselage, threaded into blind nuts. Get good quality (DuBro) blind nuts! Cheap blind nuts are not a good value...

Ideally, you should have thought this through before the nose end was assembled, and the bearers moved to suit your engine.  Steve

[Steve Agrella]

Thanks all, makes allot of sense, I'll make a motor mount.

[Allan Perret]

I would do what Allen P. suggested. It works very well. Use flathead screws countersunk into the plate, with washers and elastic lock nuts on the engine side. Use socket heads to bolt the plate to the fuselage, threaded into blind nuts. Get good quality (DuBro) blind nuts! Cheap blind nuts are not a good value...

Ideally, you should have thought this through before the nose end was assembled, and the bearers moved to suit your engine.  Steve

When I first started using the aluminum plates I used the flatheads countersunk from backside.  But after a while I had two of the plates crack right at the countersunk holes as this created a weak spot.  I changed to button head screws, also from backside.  Problem solved.  You just have to cut a little relieve where the heads are so the plate still seats flat.  I do that with a ball shaped tool in Dremel.

[Steve Helmick]

I actually use 3/16 x 3/8 6061-T6 aluminum strip, which saves a lot of sawing, and no problem with cracking. I made up a bunch of these plates waaaaayyyy back when I was working (machinist), and still have plenty! Steve

[Dwayne]

I actually use 3/16 x 3/8 6061-T6 aluminum strip, which saves a lot of sawing, and no problem with cracking. I made up a bunch of these plates waaaaayyyy back when I was working (machinist), and still have plenty! Steve

You have any pics of this process sounds like allot of work to me.

[Jim Thomerson]

I'm flying an airplane with the engine mounts done as Paul Smith suggested.  I like to use aluminum mount pads, no longer with countersunk screw heads; however, as I had one crack in two through the screw hole. 

[john e. holliday]

I use plates also, but I tap the plate for 4-40 allen head screws.  The plates are long enough to drill thru into the engine mounts of the plane.   On profiles I am doing away with the T-nut/blind nuts and going to longer screws with nyloc nuts.  Sometimes I just double up the nuts if they are not nyloc.