Spark Plugs

I've always run Autolite 295 plugs in my WD for years and never had a problem until this last plug change a few weeks ago.  I noticed it didn't seem to run as well as it usually did, but thought it just needed warmed up a little.  Well, this morning I started it up at -20C to plow snow and couldn't get it to run on any more than three cylinders and when opening the throttle it backfired quite a bit.
I pulled the new plugs and one was quite oily, but not black.  I checked the boxes and they are now made in China!! AW CRAP!!
 Any I had in the past were made in Mexico or USA.  I installed an old set of 295's that I had cleaned and regapped that were made in USA and the tractor ran like it used to and I pushed snow for the next 3 1/2 hours with never a miss.  Guess I have to find another type of plug or keep lots of good USA made ones on hand!

NGK in everything I own with an engine. Chainsaws, mowers, trucks, tractors. B-4 is plug # I use for CA and WD45.

I have also started using NGK plugs as well and have had good luck with them so far.

If you can find an old spark plug tester, where they put them under pressure and then run spark and you can see how it sparks, you can eliminate the bad plugs right there. Even test the new ones.
  A story my uncle told me, He had bought a 68 Chevrolet brand new and at 30,000 miles, he had a tune up on the car with new AC plugs. Again at 80,000 miles he told the Chevrolet service department that he wanted a tuneup and use AC plugs in it... picked up the car and went home... didn't run right, popped the hood and there were Champion plugs in there. He was not happy, took it back the next day and told the service dept that he specifically told them to put AC plugs in it.  And the nitwits tried to tell him the plugs were good.  That infuriated him, and he growled at them that they take the plugs out and put them in their tester and if everyone worked perfect, he would shut up and pay them for their service ... But if just one failed, they owed him free replacement with AC plugs tested and a genuine apology.  They tested the plugs with 30 miles on them and found three bad plugs... The service man went to the bins and pulled out another box of champions and started testing them and found two in that box... Then sent a fellow to the parts store to get AC spark plugs for the car... That was the reason why they had put Champions in, they had them on the shelves but were out of the AC plugs.  They checked the AC's and not one misfired at full pressure.  Plugs were put in and everything was retested on the car ran like it did, smooth. The establishment apologized and said that from then on they were going to test every plug that they put in.
 As for the car when it needed a tuneup, new points and condenser was put in, and the plugs checked and regapped. He drove it to 130,000 and then sold it to my nephew and he drove it to 180,000 when the transmission quit.

  We had one of those "Champion" experiences here too.  Back around 1975, I bought a set of Champions for the D17. Spring time and dad was plowing and had come in for dinner. I went and did a 'tuneup' on the tractor, new points, condenser, rotor and plugs. He went out to plow and about 20 minutes later he came hustling home and he was mad... He says, "What the HELL did you do to the tractor!!!?"  I told him...  He said put the old plugs back in... I regapped the old plugs and put them in. He went back out and plowed until he was done and came into the barn while I was choring... I asked how the tractor ran with the old plugs... 'Good' he said, Don't buy anymore Champions.  

Not trying to say anything against Creston, but, I heard someone say say not to use the resistor plugs in our old tractors. Something about the extra resistance was hard on the rest of the system. Would burn up the cap and rotor, or they would ruin the coil.

I'm have a new set of AC R45 plugs laying on the shelf. Haven't put them in for that reason.

Maybe someone could clue us in more on this.

Though Pertronix wants you to use resistor wires when you use the Pertronix II system. That system has a “brain” and I suspect the brain doesn’t like RFI.

I PUT r-45 AC in my wd and wc work great

Resistor plugs, and resistance-type wire is not a 'performance' choice, it is a design parameter requirement.  It's not a 'simple' electrical concept- it's high voltage/high frequency electrical discharge physics, and it's occuring inside a contained pressure environment that's heavily filled with stuff that isn't just natural every day 'air'.

Important to understand that while the hot-rod performance supply houses and their suppliers will marked products based on 'voltage', the voltage at that wire is only at very high voltage up UNTIL the time the arc is struck.  At that moment, the arc voltage drops to nothing, but the CURRENT jumps through the roof.  It's because the resistance of the spark plug gap is very high until it hits a critical point, where the gases in between the plug electrode and ground reach a high enough voltage differential to 'excite'... the gases glow, and become extremely conductive.

The presence of resistance limits current in a circuit... specifically, AFTER the arc has been initiated.  In the case of a spark plug, it determines how rapidly the coil's magnetic field is allowed to collapse once the arc is struck.

A common misnomer is that when the plug fires a coil, the arc will only strike once.  This is NOT the case, although, it's what the ignition designers would 'prefer'.  Light the mixture off properly on the first attempt, then be done with it.  Not the way physics like to play though.  Instead, the coil 'reacts' a bit... it swings like a pendulum a bit, before it finally assumes zero state.

On a magneto system, the 'magnetic field' that is being built and collapsed, is created by mechanical action of the mag armature, and the ignition points.  The field doesn't need to be rebuilt, because it's a permanet magnet.  It just needs to be properly phased to the points and rotor.

On a battery-coil system, the magnetic field is BUILT and collapses by the making-and-breaking of the coil's primary winding.

In the case of resistance in the SECONDARY (plug wires and plugs) circuit, it does not prevent VOLTAGE from going high... it simply prevents arc current from going to infinite value.

The result of running resistance wires and/or plugs-  the arc that starts, creates a 'burn'... and this arc's 'burn time' continues from the time corona appears at the gap, until the field has not only collapsed, but after it's done OSCILLATING.

If you use resistance wires and/or plugs, the burn time will be extended, but the oscillation energy will be substantially reduced.    The oscillation energy will usually re-fire the plug a bit, and if you have a condenser and three, five, or seven other cylinders, well, that may wind up interfering with the contact points' need to line up for firing off the next cylinder in line.

Always use non-resistor plugs and non resistance (solid core) wires, with a magneto.
Always use resistance plugs AND/OR resistance wire with any battery-coil ignition system.

Thanks for the info. Now I can put those plugs to use.

Up until around 1970 Champion was a good spark plug.

I don't know if it was imagination or what, but after I got the engine on my B unstuck, I couldn't get it started on new AL 295s (even after I fixed a mag problem), but after making some other changes and changing back to the 20 year old Champion J8s (cleaned), it started and ran well.  Could have been something else, but I suppose I should change back to the 295s and see if anything changes. 

Edited by HoughMade - 29 Jan 2018 at 2:27pm

Nicely explained Dave! About the only thing I really understood was the word “Corona “ and I don’t think my understanding of Corona is the same as yours .....