This question came up on BMTA discussion board , there was in the old days a "coil tester" which Snap-on and others made , it actually allowed you to see the quality of spark coming out of the coil and how much of a gap the spark would jump.
Joe Curto 718-762-7878
www.joecurto.com
-----Original Message-----
From: phil smith
mgpsmith@att.net [mg-tabc] mg-tabc-noreply@yahoogroups.com>
To: mg-tabc mg-tabc@yahoogroups.com>
Sent: Mon, Aug 13, 2018 5:00 pm
Subject: [mg-tabc] Coil Question
I dodged the scattered storms on Saturday to have a nice 3 hour drive around the backroads of western CT. The heat and humidity had finally backed off from the Houston-levels of the previous week. Getting off the numbered highways really takes one into some interesting territory on little-trafficked roads just right for enjoying the TC.
However, about 10 miles from home there were a couple of mild misfires pulling away from STOP signs. Then, no more than 3 miles from home it just stopped. Ignition light on, gas supply intact, but a really weak spark. Diz guts are
So I think a hot coil was the problem. Either the coil is bad (an original Q12 so that's a possibility) or something else is wrong leading to overheating of a good coil. Dwell was set on the bench at 60 degrees, what I've done on my MGs for >two decades without problem. Ammeter shows typical neutral readings when the engine is running, so I'm not suspicious of a bad control box making system voltage being too high.
Lights were off for most of this drive, and the weather conditions were hot but not brutally so. Very little standing still, but also no hard driving. Just a nice 40-45 mph cruise around the rolling countryside.
Questions therefore are:
Am I missing something or is it time for a new coil? if so, use a good used Q12 in my spares collection? Buy a new Q12? use a different coil? Is there some reason I'm not considering that would make the coil overheat?
thanks.
phil
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