GM pickup coil and ignition coil mismatch

[Tom Sharpe]

AL8001 at aol.com wrote:

> In a message dated 98-10-19 18:54:07 EDT, twsharpe at mtco.com writes:
>
> >Robert Wilkinson wrote:
> >
> >> Just read a little blurb from a service manual:
> >> "Ingnition coils with Red and White leads should be matched with pick-up
> >> coils having either a Clear, a Black, or a Blue connector.  Ignition coils
> >> with Red and Yellow leads must be matched with pick-up coils with a Yellow
> >> connector."
> >>
> >> Mine don't match, and I'm trying to trace down a high rpm miss.... think I
> >> am on the right track??
> >
> >
>
> Ez.  The different pick up coils are for different distributor rotations.  The
> GM 4 pin module ( probably others) trigger on the falling edge of the AC sine
> wave generated by the pick up coil.
>
>  If you mix pickup coils the timeing will be off 45 deg on a V8.  No problem
> you say, just turn the dist so the spark fires at the right time.  Well the
> rotor phaseing is now off, the rotor is pointing between the plug wire
> contacts.  This causes lots of spark scatter.
>
> Harold

After further deliberation, Why Does The Coil Care?  TIA Tom

PS. My ProFlow has the distributor advance welded and the ECU controls the spark
from +10 to +48 deg crank which is 19 deg. distributor or about  1.75"/(45/19) =
.75" on a large cap HEI.... Does anyone have a rotor that is 3/4 inch wide??? I
need one. I have spark scatter.