For 40/46/50 engines use #4 x 5/8 sheet metal screw the proper pilot drill size is 3/32.


Through drilling and nutting is not a good option on mounts with an angled lower beam such as Dave Brown, Ernst and some others. Without a square seat for the nut big steps will have to be ground out of the lower beam to prevent bolt from breaking with the nut not squarely seated.

John