Author Topic: Pertronix problem  (Read 167 times)

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Pertronix problem
« on: March 15, 2019, 04:15:27 AM »
Got myself a Pertronix MR-LS1 and Flamethrower 3ohm coil from Classic Alfa along with new leads, cap and rotor for my 1974 2000 GTV fitted with a Marelli S145C distributor. I installed the new leads, cap, rotor and spark plugs and made sure the engine ran  with correct timing, then fitted the Flamethrower coil (bypassing the ballast resistor) and again confirmed the engine ran.

Next I removed the condenser and points and fitted the Pertronix Ignitor following the instructions, with recommended fastening locations for the baseplate and Ignitor module for the large distributor cam setting. I tried the small cam settings but while the baseplate mounting screw locations did align, the Ignitor module didnít clear the distributor cam.

With the installation complete I confirmed I was getting 12V at the coil positive terminal by using a test light. I also confirmed that each spark plug is getting a spark. With the spark plugs fitted I can crank the engine but it wonít start, not even a stutter or cough....nothing!  I tried one of Pertronixís FAQ tips by connecting a jumper wire from the positive battery terminal to the red wire going to the Ignitor module and the engine didnít start. Double checking the static timing also came back all good.

Note that my distributor did not seem to have a separate ground wire. The condenser was connected to the points via a black wire, which then connected from the points to the connector for the negative coil wire fastened to the underside of the distributor. Could this also be the ground for the distributor (see attached photo). I donít have a multimeter to check resistance.

Iím unsure what to do next. Thanks for any help!


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Re: Pertronix problem
« Reply #1 on: March 15, 2019, 06:55:12 AM »
Youíve been methodical in your approach, itís nice to read.

The points and condenser as pictured, provide the interrupted ground to your coil necessary for a breaker point system. Provided the black wire of your Ignitor goes directly and only to the coil negative terminal, and the red wire goes to the opposing coil terminal, the module should trigger and fire. There is normally plenty of earthing in the distributor breaker plate.

Electronic ignition modules can and do fail. Iíve personally seen more than one dead 123 unit and heard of many Pertronix dying in the past on six cylinder Mustangs - but I believe the issues then are long since fixed.

Consider a $40 multimeter from Jaycar, you wonít regret it.

Colin Byrne

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Re: Pertronix problem
« Reply #2 on: March 15, 2019, 07:05:22 AM »
if your getting a spark at the plug good chance you have the wiring  correct, my money is you've changed the timing when swapping from points to the pertronix unit.  how are you checking the static timing? my method is

1. rotate engine clockwise until the static timing mark  on the crank lines up with indicator on the crank (ensuring compression stroke either via cam position or the less accurate finger over the plug hole)

2. attach a multi meter across the coil

3. ignition on so the pertronix transistor is powered up

4. rotate the dizzy anti-clockwise until the voltage goes from 0 volts -> 12 volts  (not 12v -> 0 volts, very important!)

5. confirm that rotor is still pointing to the number 1 lead when the cap is installed and that you haven't rotated the dizzy back a full 90deg

that should get you close enough to start so you can then use a timing light

And yes the dizzy will not have a ground lead, the body of the dizzy is ground

good luck, let us know how you go
72' 105 2000 GTV Red (tarmac rally/race car)
74' 105 2000 GTV Blue (road car)
68' 105 1600 Giulia Super White (Not sure yet)
01í Nissan Pathfinder (Tow car/Alfa support vehicle)


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Re: Pertronix problem
« Reply #3 on: March 15, 2019, 09:24:49 PM »
Well some success tonight advancing the dizzy by small increments and cranking the started each time. I did manage to get it started on a rough idle for about five seconds before the engine died again.

By that stage my starter was grumpy so decided to give it a rest for tonight, but promising signs finally!

Thanks for your suggestions guys!