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MG TD TF 1500 - LT Coil Voltage Leakage

Got severely caught today with my 1250 TF backfiring and refusing to run correctly thru the rev range. New spark plugs still the same result, points gap and timing AOK.

Car started fine, until the ignition system was loaded there was no issue.

More grey hair lost until I happened to observe that the tacho reduction box had rotated, it wasnt touching the LT connection on the dizzy but there was only 0.010" gap.

Fabricated a reduction box retention bracket, as per advice on this forum,clamped under the grease nipple and the generator bolts.

Problem cured, LT voltage can find the easiest path to earth where you least expect it.

Wonder how many users have torn carburetors to bits believing this was a mixture issue?
G Evans

Early on I had this problem... I solved it by splitting a piece of fuel line to cover the tach cable to act as an insulator. No problems since..
... CR
C.R. Tyrell

This happened to me when I first got my car. I had just got it running well enough to drive it and was about 10 mins away having a blast when the motor made a squeeling noise and the motor stalled. I tried to restart and it did the same thing. I took the car home on a flat bed and after some research, I discovered that the gear reduction box was dry and had bound up (the squeal) and had touched the low tension lead stalling the engine. I was afraid I done more severe damage, but was pleased to know a bit of lithium grease could solve it. I have never covered the low tension lead since. I just keep the gear box lubed up.

Alex
Alex Waugh

Post retrieved for those that are experiencing miss fires
with their engines under load.
G Evans

Distributor should be oriented as shown in the shop manual to prevent the problem of the tach drive gearbox shorting against the primary stud on the side of the distributor. Cheers - Dave
DW DuBois

Dave, which WSM image are you referring to?
Bud Krueger

Just rotate the distributor until the lead is no longer near the tach box.

Also, place an o-ring in the female side of the tach box nut. Once tightened, it will hold the box in place without the need for external brackets.
Steve Simmons

This thread was discussed between 25/04/2015 and 17/09/2015

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