Installing PerTronix Ignition Kit
Adding electronic points to your Z is a clean and easy way to eliminate mechanical points while keeping your engine compartment ‘clean’. My “engine clean up” included electronic points and new plug wires to compliment the pretty new SU carbs.
First was to add the PerTronix Ignition Kit including electronic points and a new coil, both from MSA. I selected this option over an Electronic Ignition System because I did not want an external box interfering with my stock engine bay.
The points installed easily as promised.
I also put on a new distributor cap and rotor, since I was in the neighborhood.
And the car started right up!
I went on to replace my old plug wires with some nice red Taylor spark plug wires.
Everything looked good and, at this point, everything seemed fine in paradise.
Until I hit about 3,800 RPM.
Then everything turned to shit. Flat power curve. Backfiring. Missing. Hesitation. Very slow acceleration.
Back to the mechanic for diagnostics. Fuel pressure good across RPM range (good).
Spark strong and regular across RPM range (good). I was always a believer that Spark + Fuel = running engine.
Tachometer wiring detail
The key hint was that the Tach would drop to zero and jump wildly when all this engine misbehaving started. I assumed (wrongly) that this was just a symptom.
Luckily a good friend suggested to remove the tach from the circuit – since it is easy to do.
So I traced the Tach wiring on the wiring diagram, and to my surprise, the Tach is in series with the coil and points!
Rear of tachometer, showing the pickup-loop.
I jumpered out the tach by going from the coil (green highlighted wire) to the ballast resistor (blue highlighted wire).
SNAP – full power thru the RPM range.
In the red circle, the white wire is where the wire loops through the back of he Tach. I’m guessing some inductive coupling – but whatever was going on, it was dicking-up my new electronic points.
1 and 2 are the two original connectors that went to/from the tach. 3 is the small jumper that bypasses the tach.
Now I have great RPMs and power, but no Tach.
A small price to pay for now.