IH 340 Utility Plug Gap?

JonnyB · Feb 12, 2015

I am changing over to electronic ignition & 40,000V coil. I have a 12V system. Can anyone tell me what to gap the plugs at for best all-round performance? I have only seen one comment in another forum that said .045-.060 is best, but it was for a different tractor, and this sounds too generically automotive V8 to me. Thanks in advance for any advice.

Thank you everyone for the great advice. My plug wires aren't completely new, but they are still very good, premium wires and my plugs (.025 factory), cap and rotor are brand new. Cross-fire was one of the things that I thought about when I stated that I thought it sounds generically V8, because I sensed that this old systems engineering didn't take into account this possible upgrade. Thank you all again for the great advise. This is going to speed my tuning experiments tremendously.

DeltaRed · Feb 12, 2015

"too automotive"? As if the electronic ignition
isn't? I dont think the ei cares if its on a tractor
or "automotive".45-60 sounds about right to me.

Janicholson · Feb 12, 2015

.045 will be good. Jim

Paul from MI · Feb 12, 2015

Your distributor was designed for the 12-15,000 volts of a conventional ignition system. While the electronic ignition system will generate 40,000 volts at the coil the distributor may not handle directing it to the right plug with the higher resistance of the larger gap due to short strike distances. Compare the diameters of a distributor designed for electronic ignition to an older one designed for conventional points/condensers and you'll see what I mean. I'd start off with standard gap recommendations.

Steve@Advance · Feb 12, 2015

I don't see any real advantage to a wide gap. The
wider the gap, the more likely the spark is to go
where it's not supposed to.

Wide gaps were designed to help fire the emission
control lean mixtures. It proved to be
troublesome with the cap, rotor, wires type
ignition. Now they use individual coils, one per
cylinder.

But for your application, a carburated, low
compression, low speed engine, wide gaps will be
of little advantage.

Mike in Mn. · Feb 13, 2015

More than likely the standard gap was 28 to 32, I would set it at no more than 35, couple of reasons, with all that fire the spark will take the easiest path to ground, wider gap takes more spark to fire, and your cap and rotor will be the first to go south, cross fire etc. Also with a crazy wide gap you will loose your low end torque and it won't idle smooth. Make sure you use the right coil, install a new cap and rotor and use a PREMIUM set of carbon wires, If they will fit use Autolite 3116 non resistor plugs I have used this formula on my old tractors for years, they start good and never miss a beat, and have yet to replace any components. Just what works for me.--

IH 340 Utility Plug Gap?

JonnyB

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DeltaRed

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Janicholson

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Paul from MI

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Steve@Advance

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Mike in Mn.

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