Originally posted by: Pacfanweb
SO,
NEVER LET YOUR COIL DISCHARGE WITH OUT A CONTROLLED GROUND PATH!
Test plug made from an old spark plug and a piece of wire is fine, don't pull plug wires or coil wires...
Originally posted by: Iron Woode
hotter spark means more intense and that means more current. Voltage is fixed by the coil and so is current. Your point is valid but its moot. There is a difference between factory gap specs and an engine's optimal gap. Any improvement from an increased gap will be short lived.
Originally posted by: jagec
Originally posted by: Iron Woode
hotter spark means more intense and that means more current. Voltage is fixed by the coil and so is current. Your point is valid but its moot. There is a difference between factory gap specs and an engine's optimal gap. Any improvement from an increased gap will be short lived.
I dunno, this isn't really my specialty, but it seems to me that if the plugs are getting no voltage at one time, and full voltage at another, it has to have a finite rise time and fall time, unless the entire system is superconducting (yeah right). When the primary winding in the coil is disrupted, the collapsing field will induce a rising voltage in the secondary winding. Once this voltage gets high enough to jump the gap across the spark plug, it does so. Well, if the gap is larger, the voltage will be higher by the time it's able to fire (That means the spark will be slightly retarded, but it shouldn't be a big enough difference to matter). I can't say for sure what this would mean for amperage, though...I could well imagine that the smaller gap actually has a higher-amperage spark. Still, if the larger spark ignites more molecules of gasoline and inhibits less of the flame front, it could well lead to a cleaner burn.
I don't see it as making a huge difference in mileage, but you can't claim that nothing will change.
Originally posted by: Howard
I think you're missing a 0 in there somewhere, Blunc.
Originally posted by: Pacfanweb
That's normal. I've been 90k+ on regular copper plugs. Today's ignition systems can jump a plug gap far larger than the factory spec.
The ignition system has to discharge a bigger/hotter spark to jump the big gaps, so your gas mileage will tend to increase as the gaps get bigger.
I will say that the increase isn't as dramatic with today's OBDII systems and distributor-less ignitions as it used to be.
I remember in the early 90's when the Explorers came out. They had platinum plugs, good for 60k. So I did a few, and other guys in the shop did them when they started hitting that mileage, and customers started coming back a couple weeks later complaining about reduced fuel mileage since the tune up. Reason was, the gap had gotten large enough to create a really big spark, and the combustion was better.
Originally posted by: LTC8K6
The coil has no clue what the gap is and it generates the same voltage all the time.
The fact that that voltage will also jump a larger gap, doesn't mean that it's better.
If a larger gap would work better, the mfg would use it.