That's my problem. I stuffed an OS . 25 engine into a plane that's suggsts only going up to a .19 (the SIG Wonder). The mount (and I may have been mistaken that it was a Dave Brown) looks similar to this:



The sides prevent me from getting a nut-driver deep enough to tighten the lock-nuts. I busted another mount trying it. There is literally no room to operate. I set the engine to the very back of the mount.