Triumph Repair: Triumph TR6, ballast resistor, spark plug wire

Question
Recently my running TR6 started running rough.  It began with the engine missing/losing power for a few seconds at low rpm's but then would disappear as the engine speed up.  Yesterday the car started and idled normally, however if I pressed down on the throttle it would backfire once then catch up..  It has never done this before.  I drove the car and after a few minutes it could not be driven because all the cylinders were not firing.  Eventually it just cut out and will not start.  I do not have any spark at the plugs.

The car has new OE plugs, new wires, a LUCAS Brand coil, and an aftermarket Pertronix electronic ignition.  I attempted to trouble shoot by installing the original points - but still did not start.  I have not tried to use a different rotor.
Any thoughts?  How can I trouble shoot the coil.
The most recent change to the car was I replaced the original 5-wire altenator with a factory new available Lucas brand 3-wire version from Moss Motors.  Any reason why that would cause an issue.  The original altenator had a ground wire from the altenator plug grounded to the engine block, the new one does not and apparently is built that way.


Answer
Hi Jean,
It is possible that AC current can get into an ignition system because of an alternator / diod problem but that is the less likely problem.
I would see more often and mismatched ignition system and coil or a spark jump back into the igniter form any problem in the secondary. On some aftermarket ignition systems a spark plug wire could fall off of a plug and the spark will jump to the next closest ground which was down the coil tower to the wire going to the igniter, thus destroying it.
I would contact who ever you purchased the Pertronix igniter from and find out if the coil was to be used with a ballast resistor or not and if it was the correct ohm rated coil for that system.
There is an effective good test of a rotor. Just power up the coil and take the high tension coil wire out of the cap and hold it about 1/8 in from the center of the rotor while it is on the shaft and scratch the grounding wire of the coil across a ground and see if you can jump a spark to the rotor. If you can, it is bad and if you can't, it is good.
I don't know the test procedure for a Pertronix system. If you purchased it form Moss you should call them and ask as they have a tech line and they are usually good about that.

If you installed a set of points and condenser and still didn't get a spark, You need to check to see that your points open and close and that they make a contact and brake a contact and check the coil to see if it requires a resistor or not.
let me know,
Howard