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Re: Electronic Ingition Info.

Subject: Re: Electronic Ingition Info.
From: (Denise Thorpe)
Date: Wed, 15 Nov 95 14:34:06 PST
John Bartholomew asked about electronic ignitions:

I have no information about the current options in electronic ignitions,
but I can supply some historical data.

> The integral Lucas is *supposed to be unreliable* I have no experiance
> with this yet, other than one of my B's has the module (wires cut off)
> and the XR700 installed with the distributor. It seems to work OK?
> The Lucas external amp set up, *supposed to be the most trouble free*
> I have installed in my 79B. Every once in a while it lets me down.
> I think it is the darn car saying I am feeling neglected, 'cos you are
> spending too much time with that *old* 76! The 79 just decides it is
> not going to start until you pull off the cap, look at the rotor, then
> fiddle with wires, crank & run the battery down a little, remove a plug
> and check for a spark. Then it will start! The coil has been replaced,
> the cap, rotor, plugs and wires. Whenever I have this situation I check
> for 12v at the coil etc etc. I have replaced all the connectors, bullets
> and spades. The only thing left is the magnetic pickup coil. It always
> has continuity and never a short circuit, when I check. This problem
> occurs about three times a year, so I live with it and the pain.

The electronic module that is integral with the distributor is the
original electronic ignition that came with the car.  These were all 
supposed to be replaced with the black box and a new distributor in a 
recall campaign.  Some people claim that this recall is what killed MG.

These distributor mounted units would fail when they'd been on a hot 
engine for a certain amount of time.  Then after sitting just long enough 
for the driver to fiddle with everything, the box would have cooled down 
enough to work again.  Usually, this problem would get progressively
worse (i.e., shorter periods of time on a hot engine until failure) until 
the car wouldn't run at all.

I don't know if anyone has noticed that the separate black box ignition
module is mounted in different places and with different wire routing on 
different cars.  This is because they were installed here by people with
different opinions about where they should go.  I was the one who mounted
them on top of the horizontal shelf at the back of the engine compartment
and strung the wires along the wiring harness.  I still have all kinds of
wire clamps that I didn't use left over from the kits.

> The XR700, I installed in my 72 daily driver, but removed it and went
> back to points, because I was never realy happy with the way it idled.
> The day I put the points back, it never had run as well, so I stuck
> with the points system, the module is still on the fender!

Because dwell affects timing, it's possible that the electronic ignition 
increased dwell and therefore essentially retarded the timing making the
car run badly.  Or, you needed to change to a coil designed to work with
electronic ignition.  Or, your electrical system couldn't supply the
current required by the electronic ignition.

Denise Thorpe

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