Thanks Rick,
According to the schematic:
www.cranecams.com/ignition1/wiredia1.htm
the tachometer needs to be connected between ground and the negative
terminal of the coil. The original routing for the '70 MGB is from the
battery ( ignition switch ) through the tachometer to the positive terminal
on the coil. Has anyone out there made this wiring change with successful
results?
Thanks,
Rich
-----Original Message-----
From: R. O. Lindsay [mailto:rolindsay@dgrc.com]
Sent: Tuesday, March 06, 2001 10:58 AM
To: Cady, Richard H
Cc: 'mgs@autox.team.net'
Subject: Re: optical ignition question
"Cady, Richard H" wrote:
> I have a '70 MGB where the positive lead to the coil is routed through the
> tachometer. Will an optical ignition unit such as the Crane XR700 require
> that I rewire the leads through the tachometer?
Good question Richard. Brainstorming: The tach uses an
inductive pick up, I believe, as the ignition wire goes through
a little loop inducing a pulse into the tach electronics. It seems
then, that to make the operation similar with the electronic module,
that you would change the wiring. That is, in the original setup, the
supply line to the coil is routed through the tack inductive loop.
Instead of routing the supply line to the new ignition electronics
module through the tack loop, route the OUTPUT from the module
(the bit that goes to the coil) back through the loop on the tach.
That way, the tach would still sense the current pulses. Ideas and
thoughts, nothing more...
Rick Lindsay
Diamond Geoscience Research
5727 S. Lewis Ave., Tulsa, OK
Voice: +1 918-747-3456
Fax: +1 918-747-8599
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