Triumph Repair: Ignition Problem 79 Spitfire, ballast resistor, triumph spitfire

Question
QUESTION: Hi Jim,

I am the proud owner of a 1979 Triumph Spitfire that up until recently was running just peachy. We had some issues with the car jumping timing (dizzy would not stay tight in its holder) that we fixed with a new Lucas distributor. The gist of the problem now is that I have no spark at the plugs. I've tested the wires in and out of the coil (only had access to a simple light tester) and have a strong (bright light) connection going into the coil, but only a weak (dim light) connection coming out of the coil. Here is the current wiring set up:

+red wire from dizzy
+white/yellow wire from under dash
12 volt ballast coil (maybe the problem??)
-black wire from dizzy
-black wire to small canister looking resistor
-white/grey wire from under dash

The only wires coming from the new dizzy are a red and black wire (see above for their connections)

Just a quick aside:
If you pull the spark plug wire out of the dizzy cap and place a wire tester in its position, and spin the dizzy so that the rotor comes across the contact, should the wire tester come to life as you spin the dizzy back and forth? Assuming the ignition is on of course. I did this little experiment and get no light from the wire tester, however if I place a small piece of Al foil on the tip of the rotor and repeat the above experiment, the wire tester comes to life. Is there such a thing as the rotor being too short for the cap????

Thanks in advance for the advice and happy motoring.  


ANSWER: Justin,

Not sure why you had to replace the distributor... the bracket that holds the distributor in place can be adjusted or replaced separately.

Which model distributor is it?  Is it a points type that's been fitted with a Pertronix?  Or is it a New Old Stock electronic type?

The white/yellow wire should go to the (+) terminal on the coil.  If you have the ballast resistor then the coil should be a 6V... but even with a 12V coil you should get a spark (weak) and the car should attempt to run.

There is supposed to be a small gap between the rotor and the distributor cap.  With a properly functioning setup there are two sparks each time the cylinder fires... the first is the arc inside the distributor cap as the spark jumps the gap between the rotor and the cap, the second spark is at the spark plug.


Cheers,

Jim


---------- FOLLOW-UP ----------

QUESTION: Hello again,

The distributor is a Lucas model 45D4 "True Spark", which looks to be similar to a Pertronix unit, see http://www.bpnorthwest.com/.sc/ms/dd/ee/8255/Distributor%2045D4%20True%20Spark for more details.

I'm getting power to the distributor, but the problem seems to be getting the spark to arc inside the distributor cap.  Does this sound like a coil issue?  I may try a proper 6v coil and new wires.

Thank you for your previous answer.

Justin

Answer
Justin,

First step:  contact the vendor you bought the distributor from and ask for a proper hookup diagram.

The way the coil is setup is that the + terminal is energized by battery voltage directly, or in series with a ballast resistor, depending upon the year and setup.

The coil is a transformer.  You build a charge in the primary by grounding the coil via the points (or electronic ignition) and when the contact is broken the energy stored in the coil is released into the high tension circuit.

In the 1970s there was a move away from points type ignitions as they needed frequent maintenance.  The electronic setups either worked perfectly, or died completely.

You should be able to verify that the electronic setup is working by taking the coil lead from the distributor cap, set it so there's about a 1/8" gap between the metal tip and some grounded metal (the brake/clutch master area has lots of great spots) and have a friend crank the engine while you watch for a spark.  

Cheers,

Jim