Re: Aftermarket Electronic Ignition

[SailingFC@aol.com]

In a message dated 97-09-30 22:17:46 EDT, you write:

<< > 
 > On my '78, I installed a system called the Allison XR-700.  This was over
15
 > years ago.  The Allison name is no longer around but the system is sold by
 > Crane Cams under the same model number.  The system, when I bought it, had
a
 > lifetime guarantee.  The system uses an infrared transmitter and receiver
 > with a chopper disk mounted to the distributor shaft under the rotor.
 >  Installation, IMO, was straight forward.  I did have to fabricate a
rubber
 > grommet but that was all.  The system has never needed any adjustment in
 > timing since I installed it and the specs say it can go to 7,000 rpm.  I
paid
 > $80 for it(15 years ago).  There is an ad in the November EC, page 52(no
 > price).  Another source is JC Whitney, $119.95.
 
 	Okay, I'm going to plead complete ignorance on this one.  I hear talk
 of points and electronic ignition systems, and now this infrared
 bizness.  Is there a big advantage of one over the other?  Logic (my
 logic, anyway) would state that the points are probably limited to a
 certain rpm for reasons that are beyond me.  Therefore, the electronic
 ignition steps in to cure this problem.  Okay, so now the infrared is
 here...Is it better than the electronic setup?  In what way?  Thanks for
 your help.  I dunno why I have sucha hard time with the basics, but
 that's life I s'pose.
 
 jason
 87 16V
  >>


Ok.  The XR-700 uses an infrared beam of light as a signal and this chopper
blade to make/break the beam which in turn fires the plugs via an electronic
module.  An "electronic" setup uses an electrical signal from a sensor which
fires the plugs via an electronic module or on-board computer. I don't know
of a "big" advantage from one system or the other from a reliability stand
point.  The electronic system(especially the factory system) may have a
programmed electronic map to fire the plugs based upon many inputs from other
sensors in the car and therefore may have better performance.  This of course
comes with added expense and complexity of the system.  The XR-700 is a
really good system to replace a points system without the expense of a
factory system and the complexity.  Obviously this may be at the expense of
some performance.

The points system is limited because it is a mechanical system and there is
mechanical wear as well as electrical wear(pitting) of the contact.  When it
"wears", the dwell(the time the points are closed) changes and therefore the
timing changes.  That's the big disadvantage of a points system.

Don't apologize.  This is not "the basics".

What ever you do, let us know how it turns out!

Good Luck!

-dick-
78 Scirocco
Original Owner
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