[SEL] FM Z 3hp trouble

[Tom Smith]

Hi List,

I'm a newbie and have run across a problem with a FM Z 3hp engine. I have 
restored the once very stuck engine and couldn't find a replacement for the 
busted pot metal gov. housing/mag base. I was able to locate a earlier cast 
iron unit but then found I couldn't use the Fairbanks "R" mag without some 
fairly heavy modification to the base. I then bought a Bosch mag thinking my 
worries were over. It mounts fine but when I got the timing right on the 
exhaust (per the manual), the little stud that trips the mag appears to be 
firing the mag near bottom dead center.

I transferred the gear marks to cam relationship from the replaced set and 
the valve timing appears to be on the screws so I can't figure why the mag 
timing is wrong. Its almost like I have to rotate the mag timing gear 
relative to the cam to get the spark timing right. The manual assumes I'm 
running the later R mag and doesn't give spark timing numbers (only 
alignment position of the gear tooth marks). If I have to jack with the 
timing relative to the exhaust cam, it looks like it may be a bit of trial 
and error (mostly error).

What gives?? Any help greatly appreciated.

Tom