Ignition

I installed an electronic ignition and hot coil on my M yesterday. The plugs looked good so I re gapped them and put them back in. Champion D15Y. Should I switch to a different plug. Ellis

(quoted from post at 18:04:36 09/23/12) I installed an electronic ignition and hot coil on my M yesterday. The plugs looked good so I re gapped them and put them back in. Champion D15Y. Should I switch to a different plug. Ellis

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I would look for the Autolite or AC plug to replace that.

If you used the stock gap that coil isn't going to give you much if anymore spark. As the coil discharges it's spark it builds voltage until the resistance of the gap is overcome. If that resistance is say 12,000 volts that's all it's going to make. Just because the coil can make more, like say 40,000 doesn't mean it will.

Don't expect a big HP boost. On that HP engine you may see oh around 2 HP max. Don't get me wrong. I love IE and installed on my 8N as a test figuring that if I like it I will do the M and the other 8N. I do love how it starts! WOW! Always catches on the 2nd revolution and stays running. Doesn't start, stall then restart.

Rick

How much wider would you set the gap?

Just because you switched to an EI is no reason a plug change is needed. If the one you have works well and isnt prematurely fouling theres no great need to change simply cuz a solid state switch (versus mechanical points) is being used to interrupt coil current. (EI doesnt change (much, likely none at all) a plugs operating temp.)

The operating "heat range" of a plug doesnt change based on whats being used to switch coil current. Ive had better luck with Autolite then Champion plugs, but again you dont need to change brands or heat ranges because you changed to an EI.

Many increase the plug gap if they use an EI and a high energy HV coil but its NOT required but if you do you need good high quality plug wires n cap n rotor since you have increased the firing and operating voltages. An EI and a high energy coil can increase the spark energy (E x I x Time) discharged across the gap when it fires but I wouldnt expect much if any at all HP increase although many report improved starting and idling performance when switching to an EI.

The voltage at which a plug fires is a function of the gap distance and the medium (compression and fuel) in which it fires so given the same conditions the stock coil with or without an EI switch will still fire at the same voltage. If you drastically increase the compression and are running exotic fuels (like race cars) then a HV coil (can produce higher voltage IFFFFFF necessary but still fires at same voltage as stock coil under same conditions) may be in order.

John T

(quoted from post at 04:53:18 09/24/12) How much wider would you set the gap?

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Like John said there is no need to set the gap bigger. I really wouldn't mess with it unless you are going to run race fuel or upping the compression. On the plugs, when they go bad I'd change brands. You can research it on the net but there are better plugs out there in the same price range.

One of the biggest advantages to IE is it eliminates point float at high RPM's. Much higher than an M is going to run. I like it because it's pretty much maintenance free.

Rick

We use champions all the time and have had no problem. They are now made by NGK if, that does anything for you.

(quoted from post at 12:21:54 09/24/12) We use champions all the time and have had no problem. They are now made by NGK if, that does anything for you.

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Didn't know that. I stopped using them in the mid 90's. Had an Onan engine that would run 20 hours on Champs, about 30 on both AC and Autolite and about 60 on NGK's. Engine had less than 200 hours on a total rebuild. Now I guess I'll have to check to see if they are just making em like they did or if them improved the quality.

Rick