Ignition only 7747

[Shannen Durphey]

Steve Ciciora wrote:
> 
> I think I just realized something obvious, and would like someone to tell
> me if I'm wrong.  Since the 7747 uses a distributor, and is throttle body
> injection, it dosn't need to know which cylinder if firing, right?  That's
> the distributor's job?  What I want to do is put a 7747 on my '74 ford 302.
>  It's gonna be an easier job now that I realize that detecting tdc of #1 is
> not necessary!  I plan on welding 6 equally spaced 'bolt heads' on the
> crank pully, and using an inductive sensor, like someone else mentioned.
> Does anyone know the relationship between the bolt head and TDC?  By moving
> the inductive pickup I can control the base timing, but I'd like to know
> where to put the sensor for when I design the bracket.
> Thanks for your time,
> 
> Steven Ciciora

Set your sensor at 6 degrees BTDC, with some adjustment on either
side.  The actual timing should be done in the chip, but this will
provide some driveability if the timing circuit fails, or an error
code causes the ecm to stay in bypass mode.  I think the ECM relies on
the falling edge of the signal when generating a timing pulse.
For anyone who's built a sensor this way, what diameter bolts have you
used?

Back to the Ford, why not use a GM module with a Ford electronic
ignition distributor?  You don't need a crank mounted sensor for the
TBI system.
Shannen