When Running an rx7 on the dyno how many degrees of crank rotation before spark no one at my schools dyno can give me a straight answer and in the different suggestions i have gotten have given me very different numbers, can some one help?

 

just a quick guess, i'd say its probably about 120? 3 faces so 360/3 = 120

 

i'm not even sure what you mean, so i will answer backwards

in a rotary the rotors have 3 faces, but they are geared to turn at 1/3 of the speed of the crank. since there are 2 rotors (in a 12a/13b) there is a spark/firing event every 180 degrees of crank rotation, just like a 4 cylinder piston engine.

a 3 rotor is phased like a 6, so it fires every 120, 4 rotor is like a v8 every 90 degrees, and so forth

 

Pick up the signal form the trailing coil and set it to read at 180* and it should work.

 

Thank you j9fd3s for the detailed answer, you hit the nail on the head!