View single post by Esprit2
 Posted: 02-10-2020 10:28 pm
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Joined: 05-01-2005
Location: Minneapolis, Minnesota USA
Posts: 497
At a glance, the obvious difference between the early 23D4 / 25D4 and the later 43D4 / 45D4 is that the head & cap diameters were smaller on the early models, and larger on the later ones.

The 23D4 / 25D4 are too small to accept the later Ignitor II & Ignitor III. Well... I do know of one person who installed an Ignitor II into a 23D4, but he had to grind away at the amplifier's housing, reducing it's "Outside" radius until if fit into the 23 distributor head. However, doing that immediately voids any Pertronix warranty, so you go there on your own.

The Pertronix in the photos is their first, basic Ignitor. It's a "points replacer", and little more. It is not a performance upgrade, and it cannot handle hotter coils. The basic Ignitor has no internal safeguards, and is both polarity and temperature sensitive.

Know what you're doing before you install the Ignitor, and make no mistakes. It has "ZERO" tolerance for reverse polarity, and it will instantly and permanently fry if you get the polarity wrong on any one wire. You cannot undo a backward polarity connection fast enough to save it... instantly zap-dead, and it's permanently done.

Use it with the car's OEM "breaker points" ignition coil and spark plug gap that would have been used with the breaker points. It requires more voltage to jump a larger spark plug gap. If you increase the plug gap for performance, then the high-tension side of the system will automatically run at a higher voltage. Increase the gap enough, and you'll need an aftermarket hotter coil to keep up with firing the plugs. For the basic Ignitor, keep the plug gaps at the car's original "breaker points" spark-plug gap... no greater. Either larger plug gaps or hotter coils, or both will cause the basic Ignitor to over-heat and fry.

Using a coil that is hotter than the OEM "breaker points" coil will result in a higher current draw that will cause the basic Ignitor to over-heat and fry. Acrid smelling, smoldering, permanently fried, "Dead". It has no internal temp sensor to switch itself off when it gets hot, it just fries itself to a crisp and you buy a new one.

The ignition system goes on & off as the engine runs. Picture the breaker points... open-closed-open-closed. They close to turn on and charge the coil. Then they open to disconnect the coil so the magnetic field colapses through the coil windings and fires the spark. So, in normal operation, the ignition runs at some Duty Cycle that's (??) closer to 50% than 100%. While the engine is running normally, with an OEM "points" coil, the Ignitor doesn't get hot enough to fry.

However, if you turn on the ignition switch without starting the engine (oh, say, to debug a wiring problem), then it's a lottery... or roulette as to whether the ignition circuit will be On with a 100% duty cycle (points closed), or off (points open). IF the engine's position is such that the ignition is on (ie points closed/ amp 'on'), then normal 12 volt/ 'points' coil current running through the Pertronix full time will over-heat and fry the Ignitor's amp in about 10-15 minutes... depending upon the coil's internal resistance (Re). Far less time with a 'hot' coil. As above, once fried it's dead and not coming back.

If you're going to work on your car with the ignition switch on, then either:
1) Disconnect the ignition coil, or...

2) Get your ducks all lined up, switch on only when ready, work fast, and switch off in less than 10 minutes, or...

3) Use a volt-ohm meter to determine if the ignition coil is 'ON' when the ignition switch is 'on'. If yes, then rotate the engine until the ignition switches off, and work with the engine in that position. If you're static timing the engine, then you may not have that option.

The later, more expensive Ignitor II & III both have built-in safeguards against reverse polarity and thermal overload. You're protected from making a simple mistake and frying your brand new ignition system. The II & III can also handle high performance coils without melting down, and Pertronix claims they're happier with the hotter, "FlameThrower" coils.

Tim Engel