Petronix 2

[Mikededent]

Petronix 2 users does the distributor cap handle the increased voltage? How often do you advise changing rotor and cap?

[MarekH]

Logic says that the rotor to cap gap is always a little lower than the spark plug gap, otherwise you may as well not bother setting plug gaps

I would have thought that the spark gap (or any gap) gets jumped as soon as the voltage is high enough to make the leap. This means you'll only see the higher advertised voltage if you increase the spark plug gap, because that is where the smallest gap is greatest, if you see what I mean.

Essentially, Pertronix are advertising that you can increase your plug gaps, you'll deliver a slightly more energetic spark, which is only useful if you need to light off a lean mixture. As emissions and leaner running became a thing, this had some real value. With an old carburettored car that generally runs a little on the rich side of stoichiometric, not so much, I'd have thought.

What you are really asking is "what are the consequences of making a rotor phasing error", i.e. can the spark occur (and cause damage) when the rotor and terminal post aren't lined up well enough and this is not per se a Pertronix question, because of the first paragraph above. I don't think there is much by way of choice with distributor caps and rotors and you should always be setting the default rotor angle so it always distributes, not arcs (too early), when approaching each next terminal post in the cap.

kind regards
Marek

[lowact]

I imagine that the coil voltage needs to be high enough for both gaps (rotor and plug) to be jumped simultaneously. If the rotor gap is bigger than intended (e.g. eroded) the plug gap needs to be smaller.

Even if the coil voltage is high enough, or even higher, it won't leap until its triggered. Advancing triggers as the rotor is approaching the terminal; retarding triggers as the rotor is leaving the terminal. The original V12 distributor has the rotor adjacent to the terminal for 16 degrees (= 32 crankshaft degrees) i.e.:


Higher energy (voltage) enables either: plug gaps to be increased for a physically larger spark, or plug gaps left the same for a longer duration spark.

The duration of the spark is what erodes the terminals. So if yr coil voltage is higher, you should increase the spark plug gaps if you don't want the distributor cap terminals to erode any faster than they otherwise would.