When I work with the kids to build airplanes, there are a lot of engines to assemble and/or repair. It's easiest to work on starting the newly-assembled engines when they are not yet installed into an airplane. So I have been mounting them into a test stand for that. Getting bored with having to screw in the mounting screws and then remove them when finished, I made a modification to use toggle-clamps instead of screws. When the engine has been positioned in place over the four pins, the toggle-clamps are lowered. This holds the engine into the mount for starting. Just raise the clamps to remove the engine when finished. (The test stand is mounted to a table with C-clamps.)