Who can tell me the thread size for the two long fasteners that hold the muffler on to a 40LA? I would like to change the factory supplied phillips head fasteners for allen socket heads.

My 46FX came with socket heads. Much better detail.

Had to remove the 40LA from the plane to tighten several loose fasteners, (back cover, throttle arm) but before I could get on the engine mount screws, I had to get the muffler off. No easy task on those oily little phillips head screws. Especially after the engine has been run a few times.

Also, re the screws on the back cover, How tight is tight so they don't back out again?

Thanks for any advice....