spark plugs

[exeric]

I've just made a fruitless trip to NAPA auto parts for spark plugs for my 20 J. The plug is 7/8" plug. I have been getting them at tractor meets and old car meets but they are most often used. I would like to have the luxury of putting a new plug in this thing. The only good thing about going to auto parts stores for this plug is I know more about the part than they do. Whenever I go there for a car part they treat me like a two headed idiot. With motorcycle stuff, they are clueless. They love to tell you what they think it is, or what it goes to and only as a last resort will they ask you what it's for.

Perhaps someone out there can suggest a good source for the big J plug. I'm comming up empty.

[VPH-D]

Does your 20J uses the same plug as an early Flathead, or Knucklehead? If so, use a Champion D-16.
VPH-D

[exeric]

I believe it's a 7/8" x 20 t.p.i. plug. They are bigger than all of the later plugs for H-D's. Like I said, someone told me that you could get them at NAPA but I think I'll need a part # to convince them that they have them.

My last resort is to make an adapter so I can use a modern plug, and that might be the most practical solution, but not the best.

[VPH-D]

The Champion D 16 plug is 18 mm thread. Panheads and 45 models since 56? use a more modern 14 mm thread. I think H-D only had the two plug threads, but I am not familiar with anything
older than a Knucklehead. Perhaps someone who knows the really old stuff would chime in.
VPH-D

[jww]

I run Champion D16's in my '29 JD. Should do the job in your '20.
johnny

[exeric]

A Champion D-16 plug has an 18 mm thread which converts to approximately .708" on the outside of the threads. I think H-D started using the 18 mm plug in 1927. The plugs I need are big mothers that measure 7/8" or .875" on the outside of the threads, and I was wrong before, the plugs are 7/8" x 18 t.p.i. I've heard that Ford model T's and possibly model A's used this big plug which is why they are suppose to be available at NAPA. I certainly appreciate the intrest and everyones suggestions.

[Paps]

Try a tractor supply outlet. You will be surprized what you will find in those that fit early HD. Paps

[Rod K]

I have a 1921 Indian Power Plus that uses a 7/8 x 18 plug
Auto Lite # 3076 Got it at NAPA If they don't have it, tell them
to order it . They had it in one day $4.00ea.
My understanding is that this a Model A plug.

[exeric]

Rod K, Thanks a million, I knew there had to still be a source for that plug. Like I said, it will be great to put new plugs in the J and eliminate that performance aspect.

[partshunt]

Eric, if its helpfull to ya, I'm running Champion W16Y plugs with a spare set on hand. They have been in the bike for ten years and run fine for me. I also picked up a set of Champion C-4. {comercial}? but havent needed to use em yet. You will need to check with a Champion supplier in your area, they may be special order or at least old stock in another branch outlet that may show up in thier system...I have noticed tho that replacement plugs sometimes come with the terminal unthreaded and layed out for snap on connectors rather than terminal nuts like us restores of old iron prefer.. ..Joe

[partshunt]

Eric, further to you question on 7/8 plugs, you got me diggin in my stash for more 7/8" plugs. I found another set, AC 77. However as mentioned earlier, I only run those Champ W16Y so havent tried these AC 77 plugs but you could check if they are still available. I think they are in the cooler range than the W16Y I am using very succesfully. Just plug numbers for you to try.....

[exeric]

Partshunt, thanks, I'll give those a try also. Again, I have to praise our club forum and Adminguy for making this possible. This kind of shared knowledge brings our old bikes back from the dead.

[marcina1974]

I see these plugs in competition dist catalog!
regards
Marcin

[partshunt]

Yes, I have been using a set of the plugs from Competition Dist. in my 23JD. Working very well, they look good too, apear to be nickle plated. Price was decent a few years back and probably still is... I also am using a set of NOS Firestone Spark Plugs in the 17F. No fauling yet. Need to run that 17 on a longer trip someday...then see how they be. Firestone was kinda different in color, PINK, ha ha. Good eyeball stoppers anyway...