Spark Plugs

[jwaldrich]

What is the hottest plug I can run in my Model A?

[wmws]

What are you running now and how hard do you drive your car. W16Y is a good compromise plug. Are your present plugs fouling up?

[jwaldrich]

Originally Posted by wmws

What are you running now and how hard do you drive your car. W16Y is a good compromise plug. Are your present plugs fouling up?

No. Plugs are fine but I was looking to put a little "pep" in my car. It is a fresh rebuild but is pretty gutless. I really have no A experience as I am a Model T guy who picked up a nice 1929 Sport Coupe. Am I expecting too much?

[wmws]

Changing the heat range is not going to help with "pep". That is assuming you engine is tuned right and the plugs look right. You might check the timing and you might have someone with Model A experience take a drive and see what they think.

[Ruth]

Just out of curiosity (and to answer the Op's question) what is the hottest plug that will fit in a Model A? Not planning on changing, the W-18's I am running are just fine.

[wmws]

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W95d

[Chuck Sea/Tac]

John, do you know who built the engine, or what was done to it. What’s your rear end ratio?

[jwaldrich]

Originally Posted by Chuck Sea/Tac

John, do you know who built the engine, or what was done to it. What’s your rear end ratio?

Don't know who rebuilt it but they seem to have done a nice job. Runs well and starts easy. I assume it was done in the Olympia area as that is where I found it.

Stupid me... discovered a 9/16ths nut on one axle and 5/8ths on the other. Got a good used axle and ended up putting new bearings and races in the rear end along with the axle. Never counted the teeth so I don't know the answer to that either.

The man I bought it from told me the history. The car was purchased new by a family member and passed down a couple of times. He had stage 4 brain cancer and no one else in the family wanted the car so he put it up for sale and I bought it.

[DHZIEMAN]

Simply put, spark plugs don't add pep!

[Benson]

...

[Big hammer]

The best BANG for you bucks would be a higher compression head! More seat in the pants pep :-)

[Mike V. Florida]

Here is the list,

https://www.fordbarn.com/forum/showp...20&postcount=1

This is the updated list;

http://www.fordgarage.com/pages/brum...kplugnotes.htm

[jwaldrich]

Originally Posted by Mike V. Florida

Here is the list,

https://www.fordbarn.com/forum/showp...20&postcount=1

Thanks Mike.

[BILL WILLIAMSON]

HOTTER is NOT necessarily BETTER, in spark plugs. if the plugs you're running are a nice LIGHT TAN color, leave them alone & don't DIDDLE with them.
As long as my cars ran good, I never even took a plug out for a "LOOK SEE"!
When I sold Minerva, she was still running fine, with 12,000 Miles, on some CHEEP Autolite Plugs.
Bill Practical

[barkleydave]

If your car is only a "Parade" car then a hotter plug may reduce plug fouling.
I have been using the W18 and mostly tour, but now not available they sell the "Go Plug" which I think is basicly the same.

In my opinion the best bang for the buck is the Snyders H. Compression head. Made a huge difference on my truck and 31 Slant. Loves the Blue Ridge and Smokey Mtns. now.

[Dick Steinkamp]

If you add "Pep" to your car (high compression head, longer duration cam, etc) you are actually going to want a COLDER plug.

https://www.ngk.com/learning-center/...or---do-i-need

[Mike V. Florida]

Just wanted to add this;

A heat range test is the best way to determine the correct spark plug for a particular engine set up and a person's driving habits. When in doubt always choose a colder plug first until you determine what works best. The worst thing that can happen is the plug can foul out whereas too hot a plug can cause pre-ignition and possible piston damage, i.e., a hole melted right through the piston! Some people may think it's baloney but it's the truth.

Conduct a heat range test as follows:

Drive out someplace where you can run the car at a sustained speed for a few miles without having to slow down or stop; very important. This allows the heat to build.

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 right quickly and coast over to the side of the road. Open the hood and allow the engine to cool off a bit. 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.

Now remember this .... if you run the engine and then let it slow down or idle and then check the plugs, you will not get a true indication of the heat, at speed that is. I've seen many a person judge a spark plug after an engine has been idling and use a hotter plug to get the reading they want, only to find out that at speed, the plug was too hot!

Of course this is not all 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. Also, a fuel mixture that is too rich or too lean can confuse the readings; plus a poor ignition system, poor compression, an oil burner, etc., etc.; so the accuracy of the above depends on an engine with proper function.

In conclusion, the plugs should run hot enough to keep the deposits burned off and that's it.... This means the color should range anywhere from light brown to grayish tan. Sooty black is too cold and chalky white is too hot.

Larry Brumfield

[Bob Wright]

This is a pretty good reference along with all the other tips.
Bob