In a message dated 4/14/98 11:48:43 AM Eastern Daylight Time,
mlibhart@feist.com writes:
> I recently made the conversion to the Crane ignition system and a new
> Lucas Sport Coil on the TR6. All has gone extremely well, but....
>
> Over the past weekend, I developed a slight "miss" under normal
> driving.
<snip>
> I am curious to know if this could be due to the coil running too hot.
> My new sport coil, after driving, is nearly too hot to touch. The
> bracket definitely is, due to heat transfer from the block. But the
> coil is nearly as hot.
Martin,
As you know, I have been running that same setup on my TR6 for about 6 years
now, with no problems at all. Until recently, that is, and I am now
experiencing the same sort of problem that you are having. In my case, it
only occurs after the temperature gets above normal, as when I'm in traffic.
After I drive on the open road long enough to bring the temperature back to
normal, the miss goes away.
Unfortunately, I havn't had the time to do any trouble shooting, nor do I know
of any good diagnostic procedures that don't require specialized test
equipment that I don't have, other than the old "replace and try" method. A
miss that slight is hard to see on a timing light, and it's too fast to show
up on a meter on the coil input. I will replace the coil with the Accel unit
I have on my 302 first too see if it is the coil. If not, I will re-install
the points and try that to see if it is the Crane module -- either the pick up
or the electronics. I have nearly new ignition wires, and new plugs, so I
don't think it is either of these (Iwill check them never the less). If
anyone has a better test procedure, I would like to hear it.
As for the temperature of the coil, I would expect it to be very near the
temperature of the engine after a longish drive. You have metal to metal
contact between the block and the holder, and between the holder and the coil
case. There is no insulation at all to impede heat flow. The only way the
coil could be cooler than the block would be for air flow to provide cooling
to the coil. It probably does, but I wouldn't think enough to make a
tremendous difference in temperature.
An over heated coil could be the cause of the problem though. Some of the
internal windings could be shorting out from expansion as the coil heats.
Given that I got 6 years on mine, though, I would not think that is your
problem. I would expect my coil got just as hot as yours. If it is the coil,
I would expect it's just a bum coil, rather than heat.
Dan Masters,
Alcoa, TN
'71 TR6---------3000mile/year driver, fully restored
'71 TR6---------undergoing full restoration and Ford 5.0 V8 insertion - see:
http://www.sky.net/~boballen/mg/Masters/
'74 MGBGT---3000mile/year driver, original condition - slated for a V8 soon
'68 MGBGT---organ donor for the '74
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