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SPARK PLUG ?

Posted: Thu Nov 15, 2012 1:14 pm
by johnny j
I see there are four different types (1) 18 Y light service Champion (2) 15 Y moderate service Champion (3) 18R52 moderate service Prestolite (4) 6 heavy service Champion
I got these from parts catalog TC-37F what would be the best choice for Old Nellie 1948 ser# 34846 J4 magneto. Thanks Johnny J

Re: SPARK PLUG ?

Posted: Thu Nov 15, 2012 1:25 pm
by cub47
In regards to Champion brand plugs, the higher the model number on the plug, the hotter the plug.

Re: SPARK PLUG ?

Posted: Thu Nov 15, 2012 1:28 pm
by Barnyard
Johnny, the following is from the Cub FAQ page located here cubfaq.php

Everybody has their favorite brand. Many lean towards Champions but that is up to your preference. For show, or light use you should go for a something in the heat range of a Champion D21. If you plan to really put your Cub to work then a Champion D15 or D16 would be better.

Re: SPARK PLUG ?

Posted: Thu Nov 15, 2012 2:49 pm
by Rudi
I use my Cub a fair amount. Tried the D-16's found them way too cold a plug. Went to Champion D-21's a number of years ago, won't use anything else. I tried the Autolite and the NGK's -- went back to the D-21's. Like oil it is personal preference, but for me summer, winter, spring and fall D-21's are the right plug.

Re: SPARK PLUG ?

Posted: Thu Nov 15, 2012 3:36 pm
by Stanton
What are the visible effects of using a spark plug that is too cool or too hot?

Re: SPARK PLUG ?

Posted: Thu Nov 15, 2012 6:15 pm
by cub47
Stanton wrote:What are the visible effects of using a spark plug that is too cool or too hot?


If the plugs run too cool, you normally see excessive carbon buildup and subpar engine performance, if too hot, the engine can run hotter, you have to find a happy medium.

I have always used AC Delco C87 plugs, just my personal preference.

Re: SPARK PLUG ?

Posted: Thu Nov 15, 2012 6:34 pm
by Eugene
Stanton wrote:What are the visible effects of using a spark plug that is too cool or too hot?

http://www.gnttype.org/techarea/engine/plugs.html

Re: SPARK PLUG ?

Posted: Thu Nov 15, 2012 10:35 pm
by ntrenn
Not a fan of Autolite, but we've had 3116's for years in the cub with never a fouled plug. Guess what I buy every 5 years or so....

Re: SPARK PLUG ?

Posted: Fri Nov 16, 2012 1:11 pm
by johnny j
Pulled plugs on old Nellie 18 Y champion's . Black carbon,cleaned reset gap. Running great .
Ordered new points & con,D21 Champion plugs,Dist. Cap, Thinking of doing a Sea Foam treatment.
Johnny J

Re: SPARK PLUG ?

Posted: Fri Nov 16, 2012 2:25 pm
by Rudi
Johnny:

The Sea Foam is going to help with the valves and the carbon buildup. The D-21's are a good idea. :)