MTFCA Forum

I had a pretty good week last week so I decided to throw a few bucks at some Champion X spark plugs.

They came and they really look great, but right now looking great is all they're doing because I don't know how to gap them.

Or how to measure the gap. Or where to measure the gap. Or how to adjust the gap.

And despite having had a really good week I'd prefer not to damage these plugs by fiddling around with them without knowing what I'm doing.

So here I am, confessing my ignorance, seeking knowledge, and resolving to amend my life.

I use one of these tools to gap my plugs, they are commonly available at most auto parts stores. I adjust the gap so that the 0.030 wire just slips through the gap with a light "snap".

Never bend the center electrode. Use the notched arms on the sides of the tool to bend the side electrode as needed to set the gap.

CudaMan wrote: ↑

Mon Jul 19, 2021 9:44 am

I use one of these tools to gap my plugs, they are commonly available at most auto parts stores. I adjust the gap so that the 0.030 wire just slips through the gap with a light "snap".

Never bend the center electrode. Use the notched arms on the sides of the tool to bend the side electrode as needed to set the gap.

Thanks for the explanation. I have the disc type gap gauge but I'll pick up one of the wire ones.

Do I bend the side electrode up to increase the gap?

Frankly, I can't remember which way does what, just use trial and error. The bend will be small, it won't hurt the electrode if you have to bend it a few times to get it right.

Best get a proper gauge & check what they came from champion set at - gap depends on stock ignition - in the neighborhood of .030 or distributor ignition at approx. .035 +/-.

Paddy....I run ignition on a 6 volt battery and the factory magneto at times.....considering you have proper ignition timing set, proper coil calibration checked,... clean spark plugs set at. 0.025" gap, the engine will run without fail. Having to set this on our '26, great trips for past miles worked very good. Moxie 26

One thin dime.

I run originals in my car and gap them at .032

Paddy.….. how did you make out setting gap on your new plugs ... Engine start easier, better performance..?

It depends on how good your coils and magneto are. .025 will give you a sure spark if your coils and magneto are weak, however a larger gap will give you a better spark if the voltage is high enough and the larger gap will also be less prone to carbon fouling.
So try the larger gap and if it runs smoothly and idles with that gap, use it. If it tends to missfire, try a smaller gap. If it still misfires, either you have bad plugs, or the coils need tuning up.
Norm

I find that after rebuilding the coils and set to factory specs, setting basic ignition timing with the commutator, and using cleaned or new spark plugs with gap at O.O25", will assure quality for engine starting and running despite a slightly poor battery..... Setting those plugs at 0.025" will fire even on a poor battery output, I found any higher Gap takes more power from a battery or magneto to fire.... Just by experience.

My recent experience with the brand new (modern) version of the Champion X spark plugs left me totally bewildered. I decided to add new Champion X spark plugs as the last parts to complete (and I do mean complete) '27 engine and transmission rebuild. Could not wait to fire it up and... it ran like CRAP at low speed, fair at normal driving speed. WTF? $$$$ invested and ran worse than my old tired engine? Begin the troubleshooting process.

Plug Wires: Brand New with soldered terminals

Plug Gap: 0.025" per Champion instructions and same as old Champion X plugs that performed very well previously

Coils: ECCT adjusted Excellent: All 4 coils >95% firing consistency at 0 deg timing error

Timer: I-Timer - Eliminates all timer variables (CAM centering, contact issues, cylinder to cylinder timing issues)

Magneto output: ECCT Magneto Field Strength: 21 (which is Excellent, well above average performance)

Carburetor: Vaporizer Professionally rebuilt by Russ Potter, installed with Glands and Rings per Russ's instructions to the letter. Mixture adjusted per guidance; ~1.5 turns out. Mixture adjustment does have defined sweet spot when driving at normal speed but slow speed and idle continued rough, surging, inconsistent. Must be a vacuum leak! Re-mounted twice with new glands/rings. No change. Re-installed the old Vaporizer carburetor that ran well but didn't look too good (rusty, pitted, etc.) No Change!

Started thinking about how to instrument the ignition to see what the heck was going on when my Son interrupted my thought with a crazy suggestion:

"Hay Dad, why don't you just install the old Champion plugs just to eliminate the spark plugs" Dah, OK, I guess that is low hanging fruit and should do just for completeness then I can get back to work designing a computerized data acquisition system. Well guess what? The engine started right up and purred like never before! Idles so slow and consistent you could count the cylinder firings! I could not believe it! Now I want to figure out what the heck is with the brand new (Expensive) Champion X spark plugs that cause the engine to run so poorly at low speeds with the same plug gap. Anyone have a vintage spark plug tester I can borrow?

One of the best tools I have purchased is this,I check all my plugs before installing and tweak the gap to get the best spark Peter

I was told once never to clean spark plugs with a wire brush, since the unglazed insulator around the center electrode can collect metal off the brush bristles, which will reduce its electrical resistance. If you brush a new spark plug tip with a new wire brush, you can see that material is transferred from the bristles to the insulator. Also, never sandblast the glazed insulator above the plug base. Doing so will destroy the glaze and reduce the plug's ability to resist the effects of dirt and moisture.

I'd lean toward runnning .025 with a stock ignition system, especially if the engine had more than stock compression. Modern ignition systems will generally give better results with a wider gap. The secondary voltage in a stock T coil on a car with a good magneto and wide plug gaps could get pretty high at higher engine speeds... perhaps high enough to break down the insulation in the secondary winding.

Playswithbrass wrote: ↑

Sat Jul 24, 2021 12:11 pm

One of the best tools I have purchased is this,I check all my plugs before installing and tweak the gap to get the best spark Peter

Peter,
When I looked at the picture I need to ask , Did you buy that from Australia ?

Pat, I've heard the same precautions. The plugs I used directly from the box and found them to be gaped at the recommended 0.025" but now you have me thinking. I know the HCCT fails to operate properly (missing, intermittent/inconsistent sparks) if the spark ring or pointer becomes oxidized and is easily resolved by cleaning the electrodes with scotch bright. I'm wondering if the brand new Champion X spark plugs come from the factory with a protective coating on the electrodes that needs to be removed before use. I don't recall reading any guidance in the instructions but may have missed it so will check.

Peter no I purchased it from a retired engineer who worked for champion in Detroit and restores theses a a hobby.

Mike

I, too, am less than impressed with the new "X"s. My first set came with double-cut threads at no extra charge. They leaked like crazy. Many of them made it to eBay, and the right picture of them will reveal them. Lots of folks selling nearly new "X"s for quite a while.

Next set years later really didn't run too well either.

Elderly Champions come in a range of types, actually, from the shorties for low heads, to the long reach for the new high head that Ford came out with, as well as straight sided earlier types which had very small diameter central contacts. They all run great after rebuilding and as you may guess, it's best to have all 4 be at least the same physical type for best performance. The one big warning I'd give is that there are lots of ceramic cores floating around in very different heat ranges (colder) and sometimes a mix of parts is put together in an unhappy arranged marriage. You'll learn to spot them quickly. Electrodes that look and fit like "X"s were not intended to go in T's, and yet they show up and are sold as "X"s.

here's a really good thread about them: http://www.mtfca.com/discus/messages/33 ... 1378080482

When I looked at the picture I need to ask , Did you buy that from Australia ?

Dennis, I like how you think

Scott, Thanks for the background information on the Champion X spark plugs. Seems I have some reading to do. I know spark plugs are in the chain of variables responsible for overall engine performance but really did not think they were a major contributor. If they produce spark, they are good to go! I know plugs that spark at ambient pressure may not spark well under compression (40 - 60 PSI). Same goes for heat range. Never gave all that much thought, credit, study or testing. Gotta read up and get me one of those spark plug testers Pat posted. Is there a modern source or just keep an eye on the classifieds?

A spark plug's gap can be thought of as a variable resistor. The higher the pressure in the cylinder at the instant the plug is to fire, the higher its resistance will be, and the higher the voltage required to fire it will be. While heat doubtless increases the electrical resistance of the plug's components, it may also increase the "emissivity" of the electrodes themselves, which probably run close to a low red heat under some conditions. Heat range has nothing to do with a "hot spark". It is a measure of how the plug handles the heat it picks up from the combustion process. If the working end of the plug gets too hot, it will act like a glow plug or hot tube, and ignite the charge independently of the spark impulse. This usually happens near the end of the compression stroke with the throttle well off idle. Gap erosion also increase at high heats. A plug that runs too cold will tend to accumulate deposits that can lead to fouling.

MKossor wrote: ↑

Sat Jul 24, 2021 3:18 pm

The plugs I used directly from the box and found them to be gaped at the recommended 0.025" but now you have me thinking.

Mark, last year I put some new X's in our 21 touring and found that it did not idle well with the plug gap set to 0.025:
viewtopic.php?f=2&t=14104&p=106559#p106462
I increased the gap to 0.030 and it ran a lot better. You might try increasing the gap to see if that helps.

Moxie26 wrote: ↑

Sat Jul 24, 2021 10:29 am

Paddy.….. how did you make out setting gap on your new plugs ... Engine start easier, better performance..?

I was a little skittish about bending those electrodes. Out of the box they were gapped about .010. I didn't want to do too much bending back and forth, so anything between .025 and .030 I called good.

While I'm not disappointed, I haven't noticed any better performance over the three dollar Motorcraft's that are now in the drawer. I think.

It IS starting much easier, but I attributed that to a fully charged battery and properly adjusted generator, which I did at the same time.

And after reading one of Scott Conger's posts on another thread I figured out that I was winding it up too much in low gear, like you would a Volkswagen Beetle. Shifting to high at a lower road speed has made the car run exponentially better. At least it seems like it.

So it seems I introduced too many variables to be able to confidently state that the Champion X's are making it run better. It's not running any worse, and it looks a helluva lot better!

"To gap or not to gap" or something like that..

I have found the thickness of my thumb nail has saved a few problems with plug gapping too.

Precise is great, otherwise on the road side at night with rain blowin' in, the old thumb nail can't be beat (and it works well the next day too).

A thin dime and an old Champion X

I haven't seen or heard a real dime in over 40 years.