splitdorf model c magneto

[tfburke3]

Edisons Splitdorf model c magneto was used on chiefs 34-36,after NS2,before CDH.
Parts list,thanks old croak website for pdfs,list the distributor block(cap)as firing 40-218 degrees,no mention of Indian,only motorcycles.NS2 and CDH both list Indian and 42 degrees.
Main Rotor says 42-218 degrees.
I do not understand these numbers.42 degree motor has mag timing 21 deg. offset.Front at zero,rear is 159.
Any insight appreciated.
Tom

[PaulCDF]

Tom;

I am looking in my Uncle Franks:

No.23
"Circuit breaker timing cams are ground to shape with regard to the degree angle between the cylinders. The INDIAN timer cam is made for 42 degree cylinder angle while all HARLEY-DAVIDSON timer cams are for 45 degree angle."

No. 27
"Indian motors are timed with the spark lever fully advanced (Except 4 cylinder models) and the circuit breaker or interrupter points just breaking with the piston set before top dead center (coming up on the compression stroke) according to the following specifications:"

"Indian Chief (74 cu. in. twin) 1926-1933 7/16" advance.
Indian Chief (74 cu. in. twin) 1934 and later 1/2' advance."

Hope this helps

Paul