Could be absolutely anything. Did the problem only start after the work and
new items? If so it is quite possible that one of those is faulty, heat
related failure of the coil is certainly one possibility. Fuel starvation
is another, if the tank vent is clogged. I don't know what a TD has but
non-emissions MGBs have a vented fuel filler cap. If this is replaced with
a non-vented cap you get a similar effect.
But I'd start by clipping a timing light (inductive pickup type) to the coil
lead and each plug lead, and watch the flashes both when cold and the
problem *isn't* happening to get used to how it should look, and again as
the problem develops.
If the flashes get irregular on any of the leads as the problem develops
then it is an ignition problem. If not then fuel although it could be
plugs.
If the flashes get irregular on the plug leads but not on the coil lead
(flashes here at four times the rate of any plug lead of course) then
probably the distributor cap or rotor is breaking down.
If the coil lead gets irregular as well then it is coil, points, condenser,
or any of their connections.
Connect a voltmeter between the two coil LT terminals and ground and again
get used to what the result looks like when it is not misfiring, and compare
it to when it is.
I'd expect a relatively stable 14v (once the dynamo has started charging,
12v if not) or so on the SW terminal i.e. the 12v feed from the ignition
switch. Again a relatively stable signal on the CB (distributor) side, but
this time only about half that of the SW side depending on the dwell of a
TDs points.
If the SW side starts varying when the misfire starts then it is connections
from the ignition switch. If the CB varies and the SW is as before then it
is points, condenser or coil. If it goes higher then it is the connection
to the points, or through them, to ground. If lower then they could be
closing up, condenser breaking down, or coil going open circuit.
PaulH.
----- Original Message -----
> My '52 MGTD Mark II runs fine on startup. After it warms to operating
temp, it
> starts misfiring to the point where it stops running.
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