Crank Triggered ignition

Fri May 6 20:58:20 GMT 1994

>In any case, the timing position sensor type needs to be determined.  I'm 
>told that this piece is the "weak link" in the Electromotive TEC-II 
>system.  What do people think is the best way to go here?  The TEC-II 
>uses a 60 tooth wheel and sensor to read crank postion. (a 120 tooth 
>wheel is available for distributor installations) Other crank triggered 
>ignition systems use magnets imbedded in the front pulley or harmonic 
>balancer.  Others use optical triggers.  What say?  Anyone out there have 
>any practical experience? Do tell...

A typical crank triggered ignition system - for racing - consists of a 
wheel with 4 bumps(magnetic) on it (Timing wheel).  Position is sensed by a 
magnetic pickup.  A typical system would have two pickups - one at 10 deg 
BTDC to start the car and another at 35 deg BTDC for the "run" mode.  The 
crank triggered ignition replaces the points or electronics in the distributer 
The distributer is used to decide which cylinder should fire.

Similar is the pickup arangement in GM's HEI distributer.  This distributer 
has multiple (8 for a V-8) points on a toothed wheel.  The signal to the 
control module looks like:

_________/\  ___________

The control module works like normal points as far as the coil is concerned

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