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Original Message
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| Don't go with a larger gap unless... |
| By Dave Shoe - 06/27/2001 9:38:55 PM; IP 216.243.158.157 |
...you upgrade the cap to a DuraSpark type and install the fatter Duraspark plug wires.
I'm just talking "book knowledge" right now - I don't have enough experience with this to verify my claims, but a larger plug gap only buys you a higher spark voltage - not a higher spark energy. Energy is what makes plasma - voltage only gets the plasma started. Since the plasma starts just fine at stock voltages, you don't need higher voltages.
Higher voltages work well in lean-burning emissions vehicles where it's tough to excite a reaction, and also in tough-to-combust racing fuel environments where either the fuel is tough to ignite (like alcohol) or there is just so much fuel it's tough to punch a spark through the dense mix (supercharged, nitromethane, etc).
By keeping the gap around .032-.035", you assure the plug will fire before the spark voltage climbs high enough to start leaking in other locations (like under the ozone-filled distributor cap or plug wire boot), and thus cause misfiring. A larger Duraspark cap spreads the plugwire electrodes farther apart, making it tougher to create problems under the cap when voltages climb.
If you're running gasoline and not climbing past 7000RPM, you can probably do well with a standard gap plug and a fairly stock coil. The Pertronix will definitely give you more spark energy than points could above 5000RPM. Because your spark 'energy" is determined by both the "dwell" time and the energy which the pink resistor wire under your dash allows through it into the coil, you won't gain anything by simply switching to a hotter coil. In fact, you can reduce the spark energy if you stick a coil in there which demands a lower ballast resistance wire than the car has. Ditto on changing the gap - a larger gap may give you higher voltage, but it may be a weak (cold) spark compared to the lower-voltage spark.
If you gotta have a wilder spark, you'll need to either bypass the pink resistor wire (the pink wire often starts at the fusebox and stops at the engine harness connector) and select a properly-sized (lower resistance) ballast resistor to replace it, or you need to buy an ignition amplifier (like the MSD) which uses the resistance wire as a timing reference only and draws it's spark energy straight from the battery.
JMO,
Shoe.
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