Does anyone have any info on pertronix ignition systems. i installed one on my 351 cleavland and have had problems with it. It seems like I am not getting a strong enought spark to the plugs. Is there any way to measure the voltage going to the spark plugs?

 

Ken, the easiest way to check the spark voltage is to simply look at the spark. Take a spare plug and attach a wire to it and then ground it to the block. Then look at the spark when an assistant turns the engine over. You're looking for a bright blue/orange spark with a nice "pop".

The Pertronix is a triggering device, so if the plugs are sparking at all, it's working. The spark intensity is determined by the coil. If you have a weak spark, I would suspect the coil being weak, or maybe low voltage going into it.....

 

can you check the voltage to the + side of the coil?

 

the voltage to the + side of the coil is about 12.6 volts

 

you're getting the voltage, what coil do you have? stock? might be time for a fresh one.

 

Ken, that may be part of the problem. If you're running a stock coil, it should be about 7-8v at the coil positive terminal. There's supposed to be a resistor or resistor wire to drop the voltage to the coil. When a stock coil is run at battery voltage, it gets very hot and will quickly fail. (There are some aftermarket coils that don't require an external resistor.)

It's easy to splice in a universal external resistor in the coil (+) wire, if you need to.

If you have an ohmmeter, check the ohms across the 2 smaller (+ and -)terminals. It should be less than 2-3 ohms. Then check the ohms across a small terminal and the larger distributor output terminal. IIRC, it should be about 10-12K ohms. If the coil is weak, you'll have a very large ohm reading at this point...........

 

I ran the pertronix in my 400M for a couple of months, and my dad ran one on his 360FE for about a year. The problems we had were hard starting in cold weather and just a lack of solid power at times. What we did was replaced the setup with Ford Duraspark setup. You can take the whole system out of a mid to late 70's vehicle with the same motor. Just get the complete harness and the box and distributor (if you want to rebuild) and coil or buy a new distributor and coil. You'll have to run power to it in the key on and key start positions and mount everything. It made a huge difference on both of our vehicles performance wise, plus it looks factory.
Another benefit is if anything breaks down, you still are using parts that are readily available at any auto parts store, try that with the pertronix.
Brian

 

The coil (+) voltage will be battery voltage (12.6V?) with the points open, and about 6V with them closed. When the motor is running you will get ~ 7V to 9V depending on the dwell time of the points. The Pertronix unit should act the same as points.