Spark plug interpretation

[bunnyc]

What do my spark plugs tell you? ChampionW16Y. I use 87 octane unleaded with 4 oz MMO per 10 gallons. Electrode is light gray, in case the photo colors don't show correctly on your screen.

[Dollar Bill]

They appear smutty but that could be due to how engine was run before pulling the plugs - Was it idled for awhile? You will get a better read by running at highway speed for 20-30 minutes then shut it down and then read the plugs.

[BILL WILLIAMSON]

The "business" end looks GOOD! Don't worry about them.
If a car runs GOOD, forget the plugs, you want to wear out the threads in the head? Some folks screw up their cars by DOODLING too much with them!
Bill W.

[colin1928]

They look pretty good

[bunnyc]

Thanks for the replies. Happy to know all is well. I'll keep adjusting the GAV as I have been doing.

[Mikeinnj]

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Evaluating plug insulator color after idling the engine or running at low speed will give an incorrect reading.

The correct way to evaluate spark plug insulator color is with the engine under load.:

Find a slight uphill stretch of road where you can safely conduct this test.

Bring your plug wrench with you and a pair of heat proof gloves.

After running the engine at full throttle for about 10 to 15 seconds in second or third gear, do the following at the same time:

Pull in the clutch and stop the engine.

DO NOT let the engine idle.

DO NOT let the clutch out until the vehicle has come to a stop.

Remove the spark plugs and examine the INSULATOR (the porcelain) color.

Best color is a tan to grayish-white.

White means the carburetor or fuel supply is lean and black means it is too running too rich.

Use common sense and don't do this if it is unsafe.

[Brian in Wheeling]

look good to me.
Brian

[hardtimes]

Originally Posted by bunnyc

Thanks for the replies. Happy to know all is well. I'll keep adjusting the GAV as I have been doing.

Hey bunnyc,
I agree that your four plugs pass muster. I'd like to ask if you are running a thermostat on this engine , and what (160, 180 )? I have a guess, but would like you to let us know.

[modelAtony]

Originally Posted by bunnyc

What do my spark plugs tell you? ChampionW16Y. I use 87 octane unleaded with 4 oz MMO per 10 gallons. Electrode is light gray, in case the photo colors don't show correctly on your screen.

You are using too much mmo. When you use 4 0z every 10-11-gallons you will get sooted and the area will also look flakey. on a good day you can take your plugs out let them set a little while , when they are dry you may be able to blow a little flake away. YOU ARE USING TO MUCH MMO , use it about every 3rd-- 4th tank full. Have fun modelAtony tony white Lafayette, LA

[tbirdtbird]

Your plugs are just fine.
The central porcelain insulator of the center electrode is the area to be 'read'
That Color should be gray-tan and yours are.
The peripheral area around the metal shell will always look dark with some carbon; just like the rest of the inside of the engine, where you cannot see it.
The carbon I see is dry. Not wet or damp. Not flaky.

An A is not gonna burn as clean as a modern engine because today we have higher compression ratios (which burn cleaner) (even higher than the Snyder heads) and fuel is metered in more precisely. If you lean out the carb enough to get rid of all the black, the engine will cough and run lean and you will burn valves.
I do not agree with the statement that there is too much MMO.
I have 8 various vintage cars and we run the same ratio MMO in all of them all the time and have for many years without problems. And my valves never stick.

I am gonna guess that the engine runs just fine.
Lately we seem to have ppl here who are trying to fix engines that have nothing wrong with them

[BILL WILLIAMSON]

Remember when we'd first hit the highway & the car would miss & skip, until we REALLY jazzed it up, to "CLEAN" the plugs?
Folks that drive with "GUSTO", rarely have poor running problems. OLD STALE fuel is also a COMMON problem. Some think that if it's WET, it's GOOD!
Bill W.

[1Tudoor]

Knowing how to read your plugs is about the most truthful way to diagnose how your motor is operating regardless of the type of gas engine .
A glance at a tail pipe can also indicate performance . Flying w/ Rotax 2 strokes creates a particular need to ck plugs even using exhaust gas & head temp gauges .

[Juggler]

I copied and kept this from an earlier FordBarn or Ahooga post by Larry Brumfield


Model A spark plug heat ranges
Champion W18 = close to original 3X
Depending on your driving habits, etc., a cooler plug may be the one for you:
Champion W-14 (cooler than W-18)
Champion W-10 (cooler than W-14)
Motorcraft TT-10 (same as W-14)
Autolite 3076 (same as W-14 and TT-10)
Also Champion W16Y which some people will argue that it's cooler than Champion W-18 but hotter than W-14 as the numbers would suggest. On the other hand, for years and listed as such on their official heat range chart, the engineers at Champion proclaimed that the Y means projected nose (which it is, you can tell by looking at it) and for this reason it is supposed to run hotter at slower speeds.

Conduct a proper heat range test as follows to see what is needed for your car and how you drive:
Drive around for at least 30 minutes to allow engine heat to build and then drive out someplace where you can run the car at a sustained speed on a straight road for a few miles without having to slow down or stop, very important.
Run the car up to the maximum speed in high gear that you would typically drive if you decided to drive fast and I don't mean dangerously high speed.
Hold the car at that sustained speed and without letting off the throttle, reach over and turn off the ignition. Let off the throttle, push in the clutch quickly and coast over to the side of the road. Open the hood and allow the engine to cool off a bit (allow to cool off completely if running an aluminum head).
Remove the spark plugs and examine the color and condition of the electrodes and insulators. The color will be a true indication of how hot or cold the plugs are running. But remember ... during the test if you let the engine slow down or let it idle and then check the plugs you will have changed the effects and not get a true indication. I've seen many a person let an engine idle, check the plugs and then claim they were just right only to discover later that the plug heat range was too hot.
It they are white, the plug is too hot. Go to a colder plug.
If they are black, they are too cold. Go to a hotter plug.
If they are a shade of tan, they are just about right.

Also understand that all this is not set in stone. A person who putts around at say, 35 or 40 MPH and never faster may need a hotter plug. The lower the combustion chamber temperature the hotter the plug should be. On the other hand, as conditions cause the combustion chamber temperature to rise, a colder plug may be necessary. You just don't want the plugs to be sooty black and foul out which means they're too cold or chalky white which means they're too hot. You want the plugs to be somewhere in between like light brown to grayish tan. However, slightly white may not be too bad unless it is "chalky white."

Keep in mind that the plug descriptions are for engines in good condition, correct carb mixture, good hot ignition, etc., etc.. One with bad rings for example can cause oil to get on a correct heat range plug and foul it out (short to ground down the side of the center electrode) where it won't fire. It will be black and oily.
On the other hand, a plug that is running too hot will turn chalky white or bright white. This can reduce the life of the plug or even cause the electrode to burn up. A plug can also get hot enough to glow which can ignite the mixture before the spark occurs (pre-ignition). This can be bad news... During pre-ignition the temperature inside the combustion chambers can reach WELDING temperatures in just a few seconds. The result is a hole can melt right in the middle of an aluminum piston! ... and to make matters worse it can be completely silent .. you won't hear it until it's too late .. no detonation sounds, knocks or pings.

The condition just described is for a plug with the wrong heat range (too hot) run in an engine in good condition, correct carb etc.. the same as described above. If it is known that the correct heat range plug was used then other causes such as too lean a fuel mixture, timing advanced too far, etc., etc., are overheating the plug.
This is where "reading the plugs" can be used to determine all sorts of engine problems. But as mentioned it must be known that the correct plug was used to start with.
The heat range test is used to make this determination. At the outset always choose a colder plug first if you are not familiar with the nature of the plugs said to be hotter. That way the worst thing that can happen is the plug can foul out whereas too hot a plug can cause the problems above.

This information is from Larry Brumfield the creator of the Brumfield High compression head.

[Tom Wesenberg]

And if you are going to drive the engine hard to burn out the carbon...........do it BEFORE the tune up.

If you do it after the new plugs are installed, you can foul the new plugs.
I read this in a book many years ago........plus I have first hand experience to verify that it's true.

[bunnyc]

Originally Posted by hardtimes

Hey bunnyc,
I agree that your four plugs pass muster. I'd like to ask if you are running a thermostat on this engine , and what (160, 180 )? I have a guess, but would like you to let us know.

No thermostat. My cooling system is efficient. Every now and then I measure the coolant temp with an infrared thermometer. It runs about 170 +/-.

[hardtimes]

Originally Posted by bunnyc

No thermostat. My cooling system is efficient. Every now and then I measure the coolant temp with an infrared thermometer. It runs about 170 +/-.

Hey bunnyc,
Yeah, I suspected ...no thermostat.
IMO, the best situation for an engine's happy life, is to heat it up asap to operating temp and it will then do its job most efficiently..i.e.- burn fuel mixture, according to how you have it tuned.
As said, your plugs pass muster....however, some guys comment about seeing 'sooty' appearance. This would be cleared up to a nice beige/brown color , if engine gets up to proper operating heat quickly (function of a thermostat). This is even more important, if you run your engine for many SHORT periods.
It is great to have a clean proper acting cooling system, but that same 'cool' system will cause what you are seeing on your plugs. One possible remedy , otherwise, is to experiment with hotter/hotter plugs , until you see the beige color...on /around the center electrode. Good luck

[ModAfan]

I took this picture of my four plugs after about 1,200 miles. I think they look pretty similar. I use 1 oz. of MMO to 5 gallons:

[tbirdtbird]

" that same 'cool' system will cause what you are seeing on your plugs."
what exactly are you seeing on her plugs?

the rest of us see a proper burn

[BILL WILLIAMSON]

If the insulator is APPLIANCE WHITE, they're too HOT. If they're a light TAN, they're JUST RIGHT. Disregard the BLACK, around the plug rim.
Bill Normal

[1Tudoor]

Originally Posted by ModAfan

I took this picture of my four plugs after about 1,200 miles. I think they look pretty similar. I use 1 oz. of MMO to 5 gallons:

Yes , they can be the poster perfect plugs .

No MMO here but my 1 oz treatments make me happy