Coil Pack Testing

[vlad01]

I can vouch that combustion or extremely hot gases are electrically conductive to high voltage. In fact you can use fire to bridge a spark gap completely. The spark will enter the flame and terminate there and then reform as another separate spark on the other side completing the circuit.

[MAGP]

Both plugs do fire, that is why it is referred to as a Wasted Spark system. Wasted spark systems are a complete PITA on LPG engines and are the biggest single cause of blown air boxes on LPG fueled wasted spark commodores when trying to start them. The wasted spark goes off when the inlet and exhaust are both open so the inlet tract which is filled with nice cool and dense charge of LPG goes bang.

I have never seen any noticeable difference in power or fuel economy on a bog stock engine running 1.5 mm or 1 mm gap. The important thing is to use a plug and leave it alone, if you drop it get another one don't regap it. Mostly living in small towns I have had to use plugs that were not gapped to 1.5 mm but rather 1mm. Manufacturers gap plugs at the factory and the ground electrode (or strap if you want to call it that) are different lengths for different gaps. If you get a packet of 1mm gapped plugs and regap them to 1.5 you are changing the basic design of the ground electrode and are in effect changing the effectiveness of the plug. Likewise if you have a 1.5mm gapped plug and change it to 1mm you are changing the basic design of the ground electrode. You may not think .5 or less of a mm makes a big difference but when you change the gap you are changing the angle of the electrode and unless you have microscope in your eyes you cannot see the change of angle. You may think you have successfully regapped it bigger or smaller and kept the electrode flat but 99.9999 etc % of the time you haven't and you have either made the gap smaller at some point or made the gap excessively large at another. The only way to properly regap a plug is with a set of dedicated regap pliers they keep the electrode flat to the centre electrode but the ground electrode is still moved to accommodate this.

Modified engines are a totally different kettle of fish, alot of trial and error will find the best plug gap but use proper regapping pliers rather that "feeler gauges" to regap so the electrode is at the angle it was designed to be at.

[Circlotron]

The only way to properly regap a plug is with a set of dedicated regap pliers they keep the electrode flat to the centre electrode but the ground electrode is still moved to accommodate this.

I just bend the ground strap out to whatever, then file the face of the centre electrode at an angle till it is parallel with the ground strap.
Rough enough is good enough

[Circlotron]

I have read cubic buttloads of papers on ignition systems over the years, but this one is one of the best. Well worth a read.

[Gareth]

Top read there, thanks for posting

[pman92]

I can vouch that combustion or extremely hot gases are electrically conductive to high voltage. In fact you can use fire to bridge a spark gap completely. The spark will enter the flame and terminate there and then reform as another separate spark on the other side completing the circuit.

That reminds me of bushfires and high voltage power lines, as the fire burns under them you end up with 'lightening' coming from the line to ground. Obviously a safety hazard for fire fighters who stay well away

[MAGP]

I just bend the ground strap out to whatever, then file the face of the centre electrode at an angle till it is parallel with the ground strap.

You what?

Rough enough is good enough

Please don't build a house.

[immortality]

I re-gap spark plugs with a pair of pliers and feeler gauges. Open them up by bending out through the bend of the earth strap and then slowly bringing the ground strap back down level towards the electrode. Done with a bit of care and patience it works fairly well. I'd rather the ground strap is bent a little over 90° so the gap is measured between the very end of the earth strap and the electrode rather than less 90° where the gap then occurs somewhere further back on the ground strap. Spark plug development has come a long way, these days the electrodes are smaller or have a V groove which tends to focus the spark more to one location rather than been more random around electrode.

[delcowizzid]

We've run 10s on 1.5mm plugs tapped down to 0.9mm lol now have 1mm plugs gapped down no difference lol

[The1]

Yeh ive played with gaps before and only found worse fuel economy with smaller gap, otherwise no change. So extra spark only helps keep the gap wider. 1.6mm gap no change today, will cut these MSD and N/A OEM Coils next week hopefully and post some pics, Would be interesting to see how MSD or LSX coils go with decent boost and wider gap.