Electronic Ignition

So I'm sitting here, working from home again today. As an IT guy it's nice and quite right now, so I got to pondering some things. If I were to go to a Pertronics Electronic ignition in my H, with a 40K Volt Pertronics flamethrower coil, would I see a performance improvement? Assuming a 3/916 bore with Firecrater pistons and 130# compression? If I was to go this route with the ign and coil, what should I set the plug gap to? What about if I just change th ign first, should I open th plug gap? Also, if I replaced the coil should I change the gap, if keeping the points?

Open the plug gap to ~.065 to .080 with a high output coil. As John T would say, if it goes out to the plug it came from the points (he would use more words like I usually do) The points would wear proportionatly more with a "hot" coil. The electronic ignition is designed to do it. Power improvement, yes on a dyno it might show a few % change, it is usually not seat of the pants unless the original ignition was toast. reliability hot spark for cold starts, and better consistant charge ignition all make them run better. JimN

Thanks Jim. I'm toying with the idea. I figure I'll tackle it in stages, until the "finance manager" tightens the strings I'll keep tweaking for more power and reliability as I restore it.

Chad, Its hard to give a guaranteed "perfect" answer to your questions, but I will give you my best electrical engineers opinion:

QUESTION:

Would I see a performance improvement? Assuming a 3/916 bore with Firecrater pistons and 130# compression?

ANSWER: The firing voltage is a function of 1) The medium (fuel and compression) in which it fires and 2) the plug gap. Therefore, an elec ignition with a high voltage coil will still fire AT THE SAME VOLTAGE the stock ignition would fire. The coils voltage rises ONLY high enough to arc current across the gap AND NO MORE. ALL subject to the stock ignition (say with a 20K max voltage capability) having the ability to fire the plug. Even if a coil is rated at say 40,000 volts, that dont mean it fires the plug gap at that voltage, only high enough to fire the plug, the same as the stock coil would do which (depending on compression) is in the neighborhood of maybe 5,000 to 10,000 volts or so. Its just that the HV coil has the CAPABILITY to rise to 40,000 if necessary versus maybe half that for a stock coil......

SOOOOOOOO will you see any improvement, my best guess is given that compression if the tractor was on a dyno YES there may be some slight HP improvement but I wouldnt expect much UNLESS the compression was wayyyyyyyy higher to the place the stock wouldnt fire at all. Even if theres little HP gain, however, you may still see an improvement in idling and start up (see below for reasaons)

QUESTION

If I was to go this route with the ign and coil, what should I set the plug gap to?

Iffffffff you have BOTH an elec ignition switch PLUS a HV coil I would widen the plug gap to the 0.040 to 0.050 or so range to get a wider fatter hotter higher energy (volts x amps x time) spark discharge. The elec switch gives a faster more positive current switching (no points bounce and ringing) that can handle more coil current (then points can handle) and the HV coil has the ability to rise to a higher voltage necessary to fire across that wider plug gap THEREFORE WITH A elec switch coupled with a HV coil you can discharge more energy (volts x amps x time) across a wider plug gap to initiate combustion. Thats where you may get a better star and idle even though not all that much HP gain butttttt as compression rises remember the HV ignition imrpoves performance muchhhhhhhh more


QUESTION

What about if I just change th ign first, should I open th plug gap?

ANSWER

YES Id widen the plug gap to take advanatge of the extra energy and wider fatter hotter spark if you have BOTH an elec switch and HV coil. Even at the same gap theres still an advantage due to the faster more efficient positive switching versus points switching, but to get all the advantage of an elec switch if you couple it with a high energy HV coil and widen the gap you stand to gain more in improvement.

QUESTION

Also, if I replaced the coil should I change the gap, if keeping the points?

ANSWER

If you replace a stock coil with a HV coil but keep points and widen the gap, she will fire at a higher voltage buttttttttttt you dont gain much. So if you keep the points I wouldnt see much advantage in a wider gap. Again its the combination of a wider gap (need HV coil) PLUS the elec switch (faster more current capable positive switching) that gives you the improvement. If you widen the gap with a stock coil you may be pushing the coils limits a tad versus the higher energy rated HV coil thats designed to work at higher voltages and currents then the4 stock coil....

BOTTOM LINE if you use an elec switch PLUS a HV coil and run a wider gap you gain the advantage the elec switch hss to offer and as compression rises you stand to gain more in HP plus better idle and start up

GO FOR IT

John T retired electrical engineer

Hey Jimbo, rememeber Im an attorney also and long winded by necessity cuz words are all we have to sell lol

John T

wow john, long but well worth the reading.

John,
You gave a good answer. But there is one more aspect of the question that should be added. As stated, the HV coil plus electronic switching allows you to open the plug gap for a fatter spark at higher voltage. However, an additional point is that the higher voltage is pushing the limits of the rest of the secondary system. The distributor and plug wires may cause problems when exposed to higher voltage. The probability of misfire or crossfire increase. If the higher operating voltage causes misfiring, you may loose power. Bottom line, the cap, rotor and wires need to be in top condition. Any dirt or oil inside the distributor will cause more trouble than at lower voltages.

Light a teaspoon of gasoline with a butane lighter and another with a match; then see which burns hotter.

The ignition source doesn't make a heck of a lot of difference, do it.

Allan

I pretty much agree with JimN. A few comments however based on my experiences:

1 – If you open the plug gap make sure the plug wires, distributor cap and rotor are all in excellent (eg. “new”) condition and are scrupulously clean. Otherwise moisture, dust, etc. may cause arcing somewhere you don’t want and you'll get misfiring. (Keep in mind the stock cap, wires, etc are designed for only 15,000 – 20,000 volts max.)

2 – Don’t expect any noticable power improvement from the flamethrower coil. You MIGHT see a % or two on a dyno. But you’ll never feel it in use.

3 - At the RPMs and compression that your modified H engine will see, the stock 6 volt ignition system - IN GOOD SHAPE AND PROPERLY MAINTAINED - will be entirely adequate.

4 - The real advantage of electronic ignition is it is essentially maintenance-free. You'll no longer have to deal with weak spark, timing drift, etc. caused by point and rubbing block wear.

Professors must profess! Jim

Yep you are long winded . Myself i stay out of the battle on these new fangeled contraptions . As we did some playing with then when they first came out. They did not light my fire. Played with them on a couple stockers and a couple of built engines . The best we got on a built engine was with a MSD system and believe it or not we had better luck with the old points , but the dist. was not stock as i had done my thing to it and even though the engine would not run at 8 grand the dist and points would with no break up or bounce . The electronic one was a PTIA as it just up and quite not once but twice during a pull and we went back to the tryed a true old points . But i let people do there own thing and if it works for ya go for it. Myself i have never seen any real improvement from points to electronic on the dyno . And with old points if it quites on ya ya can file them set them with match book or even the eyeball and get it back up and running where as if that electronic thing takes a dump on ya you are SOL till ya get a NEW ONE .

I went that route on 2 IH 140's and a cub, (elec ignition + 40k V coil + 0.040 plug gap) 2 yrs ago. Can't verify there is more power but ignition maintenance is now zilch, they crank 1st time everytime, and run smoother. I just got tired of messing with points/cond/etc. I would do it again just for the reliability and lower maint.

Hey John T. My wife is long-winded too. But she never charges me for her words. (At least not directly!) ...Bob M

I only have one 140, but I have the same experience as NGator with only the electronic ignition and NAPA coil with resistor. (Don't ask why there is a resistor, I was out of the country for that one.) Still .023 gap, of course. Cap and rotor seem to last longer now and I cannot figure why. Maybe NAPA/Echlin is making them better than they used to. NAPA is only 4 miles away and I have used them for everything they carry for the 140 for 30 years. I will probably upgrade coil if this one ever dies, but I honestly don't think it can run or start better than it does now.

Just wondering what the cost is for an elec ign and hv coil?

Also poses another question. Would I see much of an improvement with an engine that has a fair amount of blowby and thus probably has lower compression and burns a little oil, maybe making the oil burn up better? On the other hand I can see where it only helps the mix in the cylinder on the compression stroke so it wouldn't do anything for blowby in the crankcase.

Thanks.