Spark plug reach

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mogman
Posts: 103
Joined: Sun Oct 01, 2006 4:29 pm

Spark plug reach

#1

Post by mogman » Thu Mar 13, 2008 3:59 am

I did a search and did not see this...
The stock factory HD plugs for my 58 pan look like they are just too short, there are several threads left exposed in the head???
Craig



fourthgear
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Location: north florida
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#2

Post by fourthgear » Thu Mar 13, 2008 10:45 pm

Ya got a photo , some thing does not sound right . Are you saying they are not going in all the way and there are threads showing on the out side of the head?( not seating flush with the head )Or do you have the heads off and they are threads showing inside of the head ?

mogman
Posts: 103
Joined: Sun Oct 01, 2006 4:29 pm

#3

Post by mogman » Fri Mar 14, 2008 12:21 am

I have the heads on now so I can't take a picture, I thought I was pretty clear the plugs seem to be too short this means there are aluminium threads showing INSIDE the head.

Guest

#4

Post by Guest » Fri Mar 14, 2008 12:41 am

Sorry it does have steel inserts, I count 8 threads in the head but the #3s are fully seated with only 5 turns, the #3s have a 7/16 reach and the recomended champion RJ12YCs only have a 3/8 reach!

108
Posts: 180
Joined: Sun Aug 06, 2006 8:12 pm
Bikes: 1948 FL 74in Panhead Chopper , 1958 Zundapp Citation 500
Location: Indianapolis

spark plug reach

#5

Post by 108 » Fri Mar 14, 2008 2:12 am

I've always used 1/2" reach plugs in my '48FL for the same reason. They fit perfect.

mogman
Posts: 103
Joined: Sun Oct 01, 2006 4:29 pm

#6

Post by mogman » Fri Mar 14, 2008 3:24 am

Thanks 108, do you have any part #s
Craig

108
Posts: 180
Joined: Sun Aug 06, 2006 8:12 pm
Bikes: 1948 FL 74in Panhead Chopper , 1958 Zundapp Citation 500
Location: Indianapolis

spark plug reach

#7

Post by 108 » Sun Mar 16, 2008 11:03 pm

Sorry the reply took so long. I have Champion L92YC in the front cylinder and a L95YC in the rear. I'm sure the parts store can cross these numbers to other brands if you want.

mogman
Posts: 103
Joined: Sun Oct 01, 2006 4:29 pm

#8

Post by mogman » Mon Mar 17, 2008 11:11 pm

Thanks 108 that was a good starting place, I looked at the books and think the 95s might be a little hot for my area(not sure where your from it's already been in the mid 90s here) and the 92s are NLA so I poored over the books and found the QL77JC4. it has about the same heat range as the RJ12YC and the 1/2" reach(non projected). It's a marine plug. It may be a little cold but I would rather start cold than hot. I will keep a set of #3s in the spare plug holder just in case.
Thanks again for the help!!
Craig

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