I have a Byron fan and have a common problem with it.
Here goes. When asembled, the rotor hits the shroud. The instructions say this is "normal" and to just run the engine "in" and the contact will "wear in" by itself.
I called TopGun Aircraft and was told by them to just trim the mounting lugs on the engine mount untill I get the proper clearance. If I do it that way then the fan will not sit square in the shroud.
Has anyone come up with an alternative cure for this?
Please help me with this one.
Thank you, Marco.

Marco

Usually the fan doesn't bind very much in the shroud and is usually only rubbing on a high spot or two .

I have taken a Dremel and shaved the high spots on some of the shrouds until there is just a slight clearance. This has seemed to work fairly well.

I was like you and didn't like the idea of the fan taking the place of the Dremel being that the idea was to shave the high spots down anyway......

Rod

Thanks for the heads up. I had thought of that too but, this being my first DF jet, I was not sure if that was a good idea.
I think I will give it a try,
Thanks Rod.
Marco.

Marco, I think Rod is correct. I have used a dremel on the BVM fan shrouds and it works very well...Just don't grind on the fan itself as this will most likely make it run out of balance. "Running it in" as Byron suggests sounds like a really bad idea to me!!

I have also used shims under the mounting lugs as well to square evrything up. Doesn't take very much, only a few thou sometimes. I have never had any problems so far. I think one fan I have has about 10 thou on front and rear on the engine's right side.
Hope this helps.
Myles

I would recomend that you shave the one or two thousands needed off the appropriate mounting leg or legs. This will not cock the engine out of square, it will square it up. It is easy ,fast and has worked for me evertime. In my opinion grinding on the shroud would not be my first choice. I do not really think it would hurt anything, I just personally picked the mounting leg method. Good Luck and Happy Landings.

Something not mentioned, BALANCE the FAN !!!
I recently bought a Jet with a Byron that wasnt balanced, has stress cracks everywhere from the vibration.
I had to totally rip it apart and fix everything.
Don't shake your jet to death with an unbalanced fan.

I used my Highpoint balancer for my Heli, but any balancer you can get the fan in or on should work.

I too had a similar problem. The problem was that when the engine was bolted to the mount, it stressed the mount (warped it) and this caused the binding. What I did was I made sure that there were no machine marks on the crankcase that would cause the engine to not sit in correctly. I then beveled the inside edge of the mount (where the engine sits). This would allow the engine to basiclly drop in without any force applyed to the mounting bracket. What you should look for is the engine should sit flush or on top of the mounts and not push the mount outwards. You should be able to sit the engine on top on it drop right in without any problems. Let me know how it goes...
One more thing, the engine should not touch anywhere on the mount execpt the top of the lugs.

If your engine will not go in the mount without hitting on the sides, you have the wrong mount for the engine. The Rossi 82 mount had trhe same bolt pattern as the Os 91 but the Os hits the edges of the mount in the Rossi version. Been there dun that.

Yes its best to balance!

Noahb, I think your info. is right on the money. Although the engine should fit firmly it should not bind in the mount.
I know mine was a bit tight. I will take it apart tommorrow to fix that then I will check the clearance again.
Thanks for all the useful info.
Marco.

I hope that works. What I did with mine was pull the entire unit out of the jet, then worked with it there. Let me know if it works.
Larry