On Mon, 17 Mar 1997 11:36:07 EST thomas_pokrefke@juno.com (Thomas J
Pokrefke) writes:
>When driving, the needle on the tach swings wildly, while the engine
revs actually decline. Of course, this is accompanied by horrendous
back-firing, usually out the tail pipe but occasionally through the carb.
The deal lasts until I acclerate, and then it disappears.
>
>A quick but thorough inspection of the ignition system revealed nothing
out of the ordinary. The resistor block on the coil is cracked, but has
been that way for 3 years (a little grey tape goes a long way...). My
car has the Alison XR-700 ignition conversion .....
I'll take a crack at it. Intermitent tach accompanied by backfiring
indicates loss of current on the primary side of the coil. My guess
would be the points if you had them, but since you don't, my next guess
is that you will eventually find your XR-700 to be a diagnostic pain.
Since the XR-700 is NOT readily available at most parts stores, the only
way I can see living with one of those things is to carry another
complete set in the boot. Same applies to a Crane electronic ignition
system, and to any other non-standard component. The very thing that is
intended to make your car more maintenance free (I wouldn't say more
reliable) is guaranteed to leave you disabled on the side of the road
when it craps out.
No aspersions intended, but I like to get home, every time. I like my
40KV Lucas Sport Coil and contact points. Things couldn't be simpler.
Mind you I don't claim everything on my car to be original either. I do
have a Mollory dual points distributor, and I do carry my own spares for
it.
Barney Gaylord
1958 MGA
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