Spark Plug Info and Dissection

[Grover]

A tutorial on comparison of ready available spark plugs. A picture is worth you know a lot of words.
DSCN4506.JPG

[BudP]

Nice and informative. I especially like the cut-aways. If you belong to a local Model A club, I'm certain the membership would find this interesting.

[BILL WILLIAMSON]

It's good info to teach them that it's the insulator configuration that determines the HEAT RANGE.
I've found that most any Spark Plug, with the RIGHT Heat Range, will run GOOD in a Model A.
Dad BrandX

[Grover]

Been a member for 41 years.

[pAAt]

Grover, the more the engine burns oil the hotter the plug should be ? Elevation ? What are the reasons for using a cold plug, as compared to a hot one ? Great display, Pat

[tbirdtbird]

you are looking for a nice even medium tan color on the insulator. Then you have the right heat range.
The perimeter of the plug shell will always be black, don't look there. Whether the engine burns oil, runs lean, is at high elevation, what CR head, etc etc factor in, but often these things can't be changed. But the plug heat range can be changed.

If the insulator is white, that is too hot. If dark tan to grey to black, it is too cold

[pAAt]

Thank you for your time "BIG Bird" and all valued VFF employees !! You guys get your weekly check yet ? Laughing and rolling on the ground, with shit piles everywhere. Pat

[Dennis]

So if my 3X insulators are white I should change to a C4? I sure hate to give up my 3X's. Maybe I need to get more than 750 miles on them...
Burns no oil, B carburetor, elevation 200 ft, 6:1 head, big intake valves, B340 touring Stipe cam, 120 lbs. compression...

[tbirdtbird]

They sure are white. Could be lean, too, try opening the GAV a tad and run it around a bit before you look again.

Supposedly you have to run the car at highway speed then pull over and shut it off and pull a plug and look, but we have never needed to do that, we just drive back to the shop and recheck in the normal way. But put 50 miles on it before you re-check.

There isn't much else you can change; plugs and GAV

Another thought, get a powerful mag. glass and examine the insulators carefully. Look for any tiny silvery specs. If you find them, that is microscopic aluminum from the pistons, and the plugs are being 'blasted' from too much advance

In see no carbon on the perimeter of the plugs, unless you cleaned it off for the pic, which also makes me wonder if they are lean

[Mitch]

I have always seen 3 X'ers run good in the A engine. I would investigate further

Timing over advanced
Lean mixture
Coolant getting into the mix

[tbirdtbird]

yes! I forgot coolant

[Dennis]

Those plugs came out from left to right in the picture 4 3 2 1. notice how white and clean #2 is. I usually run the GAV about a 1/4 turn open. I'll crack it open a little more and see what happens. I'm going to try a set of flow tested jets from Dave Renner soon. Pretty much happy with the performance with a B carburetor. When you step down on it has good power and has that secondary opening sound to it. Not loosing coolant or running hot. Only run about a notch advanced maybe 2 when on a level road.

[tbirdtbird]

stock dizzy?

a little richer i think will fix you up

if you try to really load up the motor, such as going up an incline and jump on the gas does it stumble or hesitate at all?

these old motors did not care for lean at all. They will not run anywhere near a stoichiometric mix, and you risk burning valves if even a little lean

[Dennis]

No hesitation, no stumble.

[Dennis]

Stock distributor and I retard it a notch if pulling a hill before I get to that hill because I know what it might do if I don't. I'm sitting back and reading about zippers etc. and staying away from them because of the problems with too much advance, or the curve isn't right. Aren't most of them setup for a stock cylinder head? I learned a long time ago DON'T ADVANCE IT TOO MUCH. So I use the spark lever and pay attention to where it is and how I'm driving. I don't pull it down and forget about it. I almost constantly have my finger feeling between the lever and the upper stop and make sure I'm not advanced when I see an incline coming up. Same situation when shifting into 3rd gear because you have soo much rpm drop.

[Mitch]

Don't overthink it
I pull my down about 1/2 to a little less than half and leave it for the most part

[Dennis]

Do you have a high compression head? I know what happens if I pull it down too far. I was going to check total advance but the snap-on timing light gave out on me. And now the engine is on a stand upside down. I'll check it and set it so it can't be advanced too far.

[Tom Wesenberg]

Don't overthink it
I pull my down about 1/2 to a little less than half and leave it for the most part

I agree.
With my all stock engine I pull the spark half way down as soon as the engine starts, and leave it there for much of my low speed stop and go city driving.
Out on the road I'll pull it down to about 28* advance, or about 2/3 down.
Higher compression takes less advance, but only one or two notches sounds like too little advance.
On the level road pull the advance down until you feel no increase in power or speed, then if you give it some gas and it pings, retard it just a little.

[Dennis]

Mine is not a stock engine.

[Dennis]

Ok, I took one of my other B carbs and cleaned it up. Throttle shaft feels much better and I swapped the jets from the B carb I was running, they are numbered for a Model B according to Vince Ford Garage site. I should get my flowed jets next week from Dave Renner. I also used the correct venturi for a B. I can now get it to idle down to less than 550 rpm, opened up the GAV, and am now getting tan on the insulators. Spark lever now works as it should. Have not pulled it all the way down and am now at a stopping point until I get the front pulley marked for degrees advance. I want to make sure I'm not over advancing it with the higher compression or at least be able to see where that is. How accurate are the Nu-rex timing indicators? I was thinking about using a degree wheel to find my degrees advanced. The cheap timing light doesn't work except for tdc.

[Mitch]

buy a better light,, they are cheap and very handy

[Mitch]

Good news on figuring out your problem

[Dennis]

I agree Mitch... you get what you pay for. I used to buy years ago only from the Snap-on truck.

[Mitch]

CHAMPION 3X SPARK PLUG Dissection

A special thanks to Paul Modlin

http://modelabasics.com/3xplug.htm

Click here for a printable .pdf of the above drawing.


3Xparts.gifrecreation11-14-27dwg.gif3XcompareFade.gif3XEarlyAni.gifAutoTradeJournal.gifmadeInUSAearly.gifmadeInUSAlaterII.gifmadeInUSArepro.gifsectioned.gifPLUGgAP.gifexplodeEarlyRepro.gif3xEarlyFrnt.gif3xLaterFrnt.gif3xReproFrnt.gif

Note:

• All spark plugs that are considered "Original" had a rounded 3
• Champion 429 Spark Plugs can still be purchased. O'Reilly Auto Parts

Original			Reproduction
Used Up To Early 1930	Used After Early 1930		Champion 429

All had a "3" with a rounded top. The lettering on the porcelain varied from thick to thin and from light orange to dark red

The original plug gasket was a copper wrapped asbestos washer. The copper was rolled over the edge and the asbestos was not visible.


Notes for creating web page.

Interesting Facts

All materials conduct electricity, some just oppose it better than others; hence an insulator.

The Albert Champion Company introduced the “X” spark plug in 1909


“The Champion “X” insulator is what is known as the petticoat type. This insulator is generally conceded to be less liable to foul than insulators of other types, due to the fact that the surface over which the current must travel is greater. Furthermore, these insulators are able to resist fouling, as they are made of material which will not absorb oil: the glaze on the surface is smooth and hard so as to keep the oil from adhering to it.”
Ford Service Bulletin No. 11 Monday, September 1, 1919 Page 81


“Insulators must be strong electrically. Every porcelain insulator is called a di-electric. The material is an insulator at certain temperature, while at others, it becomes a conductor.”
Ford Service Bulletin No. 11 Monday, September 1, 1919 Page 81


If the porcelain is fouled, it should be cleaned with a cloth dipped in gasoline.
Ford Service Bulletin No. 11 Monday, September 1, 1919 Page 81

[Flathead]

Thanks Mitch!

[Mitch]

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[1930 Closed Cab PU]

Another reference for choosing spark plugs

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[JDupuis]

Good article
Thanks for sharing.

[aford193031]

Very good article. Thanks for sharing.

[N97323]

Digging through this post and there is an entry that the Champion C-4 plug was not recommend for the Model A, however almost all of the engines I recently tore apart had C-4 plugs in them. Were they used in an application where the engine would be running at a constant speed?

[Mitch]

Digging through this post and there is an entry that the Champion C-4 plug was not recommend for the Model A, however almost all of the engines I recently tore apart had C-4 plugs in them. Were they used in an application where the engine would be running at a constant speed?

The C-4 was recommended for the new 1932 V-8. The Model B 4cyl continued to use the 3X. I don't have that SB in front of me but it does explain things better. As time past the C-4 was pushed more for use in the A, by suppliers but it is a cold running plug. Maybe because of the cost factor??

[Mike Peters]

3X Spark Plug Question

Original Thread

I just discovered that all 3x porcelains are NOT created equal. The example on the right just came out of a 28-29 base. As you can see, it is cracked from stem to stern. The porcelain to the left is a spare I've had for years and I thought I would replace the cracked one and end up with a working original 3X sparkplug. Wrong! The good porcelain on the left would not fit into the original 28-9 base that the porcelain to the right came out of. If you compare the tapered bases of the two porcelains, you can see that the good porcelain on the left has a fatter taper on the electrode end than the cracked one on the right. That's why it won't fit the 28-9 base. I don't know if the good one on the left came out of a 28-9 base or a 30-31 base. Are the early 3X plugs different internally than the later ones from 30-1? Has anyone run into this before? Thanks.

[CarlR82A]

Your correct, early 3X with large hex will not inter change with later small hex base.

[Mike Peters]

Thanks Carl. So the early and late 3X components don't interchange. That means that my spare porcelains are 30-31 only. JDupius, if you shoot me an email, I can send you back the photos. [email protected]

[JDupuis]

Thanks Mike
Email on its way.

[Marco Tahtaras]

They also made one between them where the early base was machined for the new core. They are very uncommon.

Champion_3X-02.jpg

3x-01a.jpg

[Jeff/Illinois]

Something I never understood and I haven't located the 'why'.

Why did they go to the bother of knurling a spark plug?

[Brad in Maryland]

Speaking of "not all 3X porcelains being created equal", how about this French Champion 3X:

fullsizeoutput_33c8.jpeg fullsizeoutput_33ca.jpeg

If you happen to have three more of these laying around that you don't need anymore, I sure could use them for my French assembled Model A. 🇫🇷

Brad in Maryland

[JDupuis]

image.jpg image.jpg image.jpg image.jpg

[alexiskai]

This table was printed in the Aug. 1932 service bulletins. Notice the correlation of recommended plug gap to compression test results. Good baseline for those running HC heads.

[ndnchf]

I stumbled onto this old thread and it got me wondering how my Champion W18 plugs were doing. So I pulled them out and the insulators are white, not tan. So they seem to be too hot. The motor has a 6.1 head, Marvel carb with GAV set about 1/3 open. It runs just fine, but now I'm thinking I should spring for a set of 3X plugs. What do you guys think?


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