Boots with Legs,
Hmmm....I kind of been thru this recently with this exact mount. The hole pattern in the Dave Brown mounts is trapezoidal, so you can forget about just rotating the mount. In my prior post about the Red 'Pants OPP (Other Peoples Planes--Fancy Pants) I went thru the whole deal. And, the reason that rotating around is impractical is because of the change in the spraybar location with respect to the tank. Again, if this is of interest, go find those posts....
As far as the idea that you can "install the hole spacing you need on the backplate" I'd say check that idea very carefully before you plug the drill in. It did not look feasible to me--or I would have done it.
I also have an igNoblarf OPP which came to me second hand with a Dave Brown mount. The holes in the firewall were in the wrong place vertically for the tank run to ever work. (Flooded the engine if you tried to invert the plane.) So I made a butchplate out of plywood to convert one hole pattern location to another that worked. So a hole pattern with clearance holes for countersunk screws that matched the existing firewall pattern, and a second pattern that matched the DB mount and had blind nuts and which translated the pattern vertically until the tank centerline was lined up. That worked out very well, so maybe the same idea would allow you to do whatever it is you are trying to do...? I can send a photo if that helps explain it.
I thought I remembered a square-backed mount, might have been metal, and maybe the pattern was symmetric in both directions. I looked in the OS accessories and didn't see it. Maybe a Tatone or a Craft Hayes? You can check MECOA for these.
The Divot
Topic: 25 motor mount (Read 723 times)