[Fot] Mallory condenser problems

[Robert Lang]

Hi,

I'm running the Mallory dual point on both my TR6's. On the street car, I 
had the exact (or similar) behavior where condensors go bad in an 
unpredictable manner. On the race car, I had problems when I first put the 
car together, but I did play with the wiring and more than once wound up 
wiring the ignition wrong which led to no start conditions and head 
scratching.

I use a slightly different coil setup for either car, though.

On the race car, I use an MSD blaster coil which has no internal 
resistance, so I installed an MSD ballast resistor. That setup seems to 
"eat" less condensors than when I first installed the Mallory dizzy. But 
if the car is raced on a very hot day, there is some likelyhood that the 
condensor will fail or start to get flakey.

On the street car, I just carried a couple of spares condensors. I tried 
all sorts of combos in that car. I started with a Crane PS20 (I think) 
coil (it was already there from when I ran the Crane X700 ignition box). I 
switched to the MSD Blaster (TR6 has a built-in ballast resistor) - still 
got failures in what seemed like random fashion. I even bought a Mallory 
coil - that _should_ work, right?

I eventually gave up on the points in the street car and bought a 
Pertronix Ignitor this year. Owing to the reported "reliability" of the 
Pertronix, I elected to carry a spare unit in the boot (along with the 
Mallory dual-point setup - both are ready to drop in at a moments notice. 
So far I've gone about 2k miles with the Pertronix with no probs - knock 
wood.

For the street car, I was sure that the problem was related to the use of 
an electric tach because if I left the tach disconnected the points seemed 
last thousands instead of hundreds of miles. However, while I've been 
writing this response I thought of another possibility that might come 
into play.

On TR6, when you turn the ignition key and engage the starter, a wire on 
the starter bypasses the ballast resistor to give 12 vdc to the coil. I 
wonder if the extra voltage through the coil (the MSD and Crane both have 
ZERO internal resistance) is a prob for the condensor.

Here's something to try - if TR3 bypasses the ballast to the coil (I have 
no idea how the TR3 is wired) when you start the car, try keeping that 
wire off the coil and see if the condensors last any longer. On TR6, 
there's a white wire with black trace that is the 12 feed to the dizzy. On 
the stock wiring harness, the push on connector is shared with the 
ballasted wire from the ignition switch, so rather than hack that, you 
could just leave the other end off the starter (but use a tie wrap to keep 
it from hitting the exhaust header) and see if that works.

The only other thing that I can think of is heat-related internal failure 
of the condensors, but that's a stretch, at best.

As a point of information, I asked the exact same question that you ask 
about 2 or 3 years ago on this list and at least one other Triumph list. 
The feedback that I got was inconclusive but practically nobody said "oh 
ya, I had that problem". I found the lack of similar experience to be 
frustrating at the time.

But if TR3 has a 12 volt feed while you're cranking the engine, try 
bypassing it so the coil always gets 6 volts and see if the condensors 
last any longer.

FWIW, Summit Racing sells the Mallory condensors (#400) for about $8. 
They've gone up about $3 in the last 3 years, but I've never had to 
backorder and I get three or four at a time to spread the shipping costs 
out.

Let us know if the suggstions work.

Regards,
rml
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