I drilled 3 pilot holes in the idler plate. All are 3/32" dia. I’m not exactly sure what size to drill the final holes. Two of the holes are called out at 1/4" and one is for an AN3 bolt. I haven’t figured out what goes in the 1/4" holes and I have found conflicting information on the AN3 bolt. Some literature says to drill it 3/16" and some info says I should drill it smaller so that I have a tighter fit on the bolt. I left the part with the pilot holes and will open them up later.
Welcome to my builders log for Sonex S/N 767. It won't be as big as a real 767 but if you scale the speed I bet it will be almost as fast
Dave's Sonex Builders Log 