Spark Plug Condition
 

I recently started having a little bit of a lope in the engine at slow idle. I’ve put 2000 miles on the car since I bought it last August. I don’t know how many miles were on the plugs prior to that. Cleaning and re-gapping the plugs to .035 seemed to fix the issue.

The plugs had some carbon on them, but the insulator and electrode seemed fairly clean. All four plugs were the same.

I’m still pretty new to Model As. Is this what you would expect with plugs in a Model A?

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Re: Spark Plug Condition
 

Might be a little too much carbon on tbe plugs but the insulator in the middle is the correct tannish color you want to see. If the car works okay now, I would stick with it. Or you could get new plugs if it would comfort you.

Re: Spark Plug Condition
 

Probably running a little rich, which you have to do in cold weather to get it to run until it warms up. See how they do, a lot of carburetors run 1/4 turn mixture but it really depends on the condition of the gav needle valve. An air filter may act like having the choke on slightly depending on the filter, since original A's didn't have any filters.

Re: Spark Plug Condition
 

I do have an air filter. The previous owner told me not to adjust the GAV, just leave it alone.

If I want to run a little leaner, which direction should I turn the GAV?


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Re: Spark Plug Condition
 

The car starts easily. I don’t want to risk messing that up.


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Re: Spark Plug Condition
 

To check plugs on an A - run the car for a while at med to cruising speeds/rpms. While at higher speeds turn off the ignition, gas lever up immediately, cost to somewhere to park, and check the plugs.


A lot of the black, slightly sooty condition is caused by the idle jets, and possible the jets running rich at around town. Lower RPM (below about 700 rpm also runs off the GAV, and that can tend to be rich. This is normal.




Usually I pull & clean up the plugs with Carb Cleaner and a lint free cloth, reinstall them and go for a ride of an hour or more in teh country.


Since this is very old tech, they do not run clean like a modern car with electronic ignition and fuel injection.

Re: Spark Plug Condition
 

clockwise leans mix.

Re: Spark Plug Condition
 

Here is a short video on how to clean them.
Yours look black and fuzzy. Time to clean them. Keep them clean and those plugs will last a very long time. Our plugs do foul and it is easy to clean them.
https://www.youtube.com/watch?v=4hHT...cz4R0&index=35

Re: Spark Plug Condition
 

How far should I turn it to make a difference? 1/2 turn?


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Re: Spark Plug Condition
 

Thanks for sharing the video. I did clean the bottoms with a wire brush, but I didn’t think of cleaning the electrode area of the plug. Do you have any idea where to find a skinny file like that?


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Re: Spark Plug Condition
 

Typically, to start a Model A, you open the GAV a turn or so counterclockwise from completely closed. After warm up, turn it down clockwise to a quarter turn or so to run. I don't know why your previous owner told you not to touch the GAV. It's there for a purpose for fine tuning.

Re: Spark Plug Condition
 

Harbor freight.
https://www.harborfreight.com/12-pie...-set-4614.html


Most hardware stores and big box home improvement stores may have them. Sometimes also called jewelers files.

Re: Spark Plug Condition
 

Mikes info is good.


Also check the Model A Instruction Manual for basic info. Lots of good stuff.

Re: Spark Plug Condition
 

Will not attach, most likely too large of a file to attach.
here is a link, Click on "Click to download model a manual".




http://www.motormayhem.net/model-a-f...owners-manual/

Re: Spark Plug Condition
 

Experiment with the GAV. While the engine is running, turn it clockwise until it stops, thats full lean, then open just enough for smooth idle, for most engines 1/4 turn. When cruising down the highway, I usually lean the engine out, to maybe an eighth turn, then when slowing down open it back to a quarter, or even a bit more. Driving a model A takes both hands, both feet, ears, and brain. If your new to an A, you really should get a copy of the original owners manual and read it well. It will dispell a lot of the bad advice that you will undoubtedly get.

Re: Spark Plug Condition
 

When slowing down if taking your foot completely off the gas a cough/popping sound is heard, means things are on the lean side. Could just need a little more GAV counter clockwise, or could be your carb idle mixture screw needs tweaking. This most likely will not cause damage/issues. Just one of the fine points in running an A. I agree with eagle above, this is the fun/enjoyment of driving an A, being involved and tuned into maximizing the operation of an A.

Re: Spark Plug Condition
 

I turn my GAV several times, it really makes a difference. If your car starts and runs fine then it may be open too far once the engine is warm. Just turn it clockwise and keep track of how far it turns until it stops so you can put it back there when starting. It really depends on the individual carb as to where it should be run going down the road, assuming your carb matches a stock one, it is about 1/4 turn counter clockwise from stop. When you get to stop on turning it, don't force it as it will cut a groove in the brass. I have one all apart if you want to look at what is going on inside the carburetor.

Re: Spark Plug Condition
 

You plugs don't look too bad, I run w-18 champions a little hotter plug but still have black soot. A lot of stop, go and idle driving here...

Re: Spark Plug Condition
 

Forget the file. Find a old time gas station that performed tune-ups and ask to have them clean your plugs on their plug cleaner. Carry a spare set.

Re: Spark Plug Condition
 

I found when I ran motorcraft plugs they were a tad on the cold side. When I switched to the 'original' style plugs the car started running much much better. So may try a hotter plug from Champion.


Mike