I recommend that anyone planning to own and operate the 90 hp. Franklin, obtain the manual for the 4AC-199 series. Read it and understand it. Franklin had some different ideas on building an aircraft engine. These engines have been around quite a while and too many "farmyard mechanics" have had their "fingers in the pie."
I have a fair amount of experience with the six cylinder Franklins, both pre and post war. Now, I too have inherited a "90."
Who knows what I'll put it on.......
Dan