NGK Spark plugs

james.heider

james.heider

Senior Member
I went to my local NAPA store and ordered NGK A-6 spark plugs for my 36 21 stud motor. That NGK number was given to me here on Fordbarn.
The plugs they sold me are stock number 2120 and say D8EA.

This is what they cross referenced. The plugs don't fit, they fall into the spa
spark plug holes. Is there another number for this A-6 plug? NGK stock number?

Thanks
 
I believe you need to ask for an AB-6 or AB-7. I'm pretty sure the standard A series has been discontinued. You need an 18mm thread, they gave you 14mm.
 
I tried a set of NGK and threw them in the trash can after nothing but fouling. Went back to what ive been using for 20 yrs, Champ D-21 never no troubles with them. Their an 18 mm plug. And i have the small knerled brass nuts that fit them with the correct wire ends [curved wire ends] ken ct.
 
ken ct said:
I tried a set of NGK and threw them in the trash can after nothing but fouling. Went back to what ive been using for 20 yrs, Champ D-21 never no troubles with them. Their an 18 mm plug. And i have the small knerled brass nuts that fit them with the correct wire ends [curved wire ends] ken ct.
Click to expand...

It's a strange world.... I had the exact reverse situation.... Champions were crap and NGKs ran much better. :confused:
 
I wonder if that issue is hemisphere related. LOL. Just kidding, I couldn't resist the comment.
 
James, That A-6 number I gave you is correct and is what I am currently running in my 35. They have been troublefree, but so have the Champion D16's that I have previously run. There are differences; the D16's have a 7/8" hex, the A-6 have a 1" hex, [as do the original equipment Champion 7 com's], so a different socket will be required, other than that, I have been unable to ascertain any difference in performance of either brand. Brian
 
I agree the brand of plug should not cause a problem. The heat range of the plug will have more effect on fouling and life span.
 
SigmaRho1416 said:
I believe you need to ask for an AB-6 or AB-7. I'm pretty sure the standard A series has been discontinued. You need an 18mm thread, they gave you 14mm.
Click to expand...

The AB-6 spark plug is a NAPA # 2910 and matches with specs of :
Attributes :
Spark Plug Hex Size : 1"
Spark Plug Reach : 3/8"
Spark Plug Seat Type : Gasket
Spark Plug Thread Size : 18 mm

The #2120 or D8EA is actually a 12mm thread and is an incorrect inerchange. The A6, as Brian suggested is the old number and has been replaced by the AB6 / 2910
 
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Thanks Uncle Buck,

I called NAPA this afternoon and they ordered 8 AB-6 plugs for me. Will pick up in the morning and return the 2120.

Thanks Again for the help
 
34 Then why did the fouling go away when i reinstalled the Champs.And this was on 1 plug only.I also put in 2 new plugs in that cyl and the second one did the same thing. Why did it not foul with the Champs after i put them in ?? ken ct.
 
Ken: It is possible the fire voltage on the Champ and the NGK are different. Could be the NGK was telling you the voltage was too low on the one plug to fire correctly. I would look over this one plug wire to see if it doesn't have a problem.
 
There has to be a reason why Ken had the fouling experiance with the KGKs. I think heat range is the most likely cause. Attached is an article and diagrams I lifted from a spark plug site. Differences in the manufacturing process can have an effect on the actual heat disipation of a plug.
 

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  • Spark plug heat disipation.jpg
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They were supposed to be a direct cross for the D-21 champ. Maby wasn't ?? ken ct. But im back useing Champs. Have never had any troubles with them. ken ct. 21 is a hot plug.
 
Spark plugs are like politics. I've had problems with all the brands at one time or another. If you find a brand that works for you, use it till it doesn't work anymore then try another and see what happens.
 
Brands that worked great for people the last 30 years may not work as good today since many named brand mfg. are buying from china. At least the NGK's are made in the USA.
 
Over 18 sets of Champ over the past 20 yrs and never any trouble. I change once a yr,i will keep using them till i have troubles with them. They work for me. ken ct.
 
All of the blower motors I have built have gone out of the door with NKGs in them. never had a come back because of the plugs. Some have gone with weber carbs some have gone with 97s and some have gone 94s. A few have be fuel injected. The NKGs will get the job done, for me.
 
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