Champion plugs for 70 25hp, J8C is called for

[fishonboat]

I am reading a lot of these posts about what plugs are used in these older motors. Both of my service manuals say J4J is the plug to use. We all know that that they no longer make the J4J. I see post saying to use the J6C but if you look in the Champion Spark plug books or there web site http://www.championsparkplugs.com/results_appOther.asp?otherMotiveID=12442&mfid=2 It tells you to use the J8C or RJ8C. So who is right, Champion or the posts? <br /><br />P.S. if you are looking for a Champion plug go to the link above you can find any plug for most any motor you have.

 

[BoatBuoy]

Re: Champion plugs for 70 25hp, J8C is called for

The site to which you refer is actually sparkplugs.com<br /><br />sparkplugs.com<br />P.O. Box 772<br />Sun City, CA 92586<br /><br />This is NOT the actual Champion factory website. I've seen errors on this site. For the most accurate info check here boatsetup.com

 

[R.Johnson]

Re: Champion plugs for 70 25hp, J8C is called for

The plug you want is now called a J4C.

 

[fishonboat]

Re: Champion plugs for 70 25hp, J8C is called for

I went to BoatUS to pick up the J4C and they didn't have them nor did the Champion book list them. Any thoughts?

 

[CATransplant]

Re: Champion plugs for 70 25hp, J8C is called for

Go to an auto parts store. I got mine at a Mills Fleet Farm in MN. They're pretty common plugs. Your local NAPA auto parts store will have them.

 

[fishonboat]

Re: Champion plugs for 70 25hp, J8C is called for

I called Napa but they don't have them in stock. I did call the Johnson dealer and they do have the J4C's in stock. I will take the J8C's back to BoutUS. I'm a little surprised that the only thing I could find in the Champion Catalog at BoatUS stated J8C was the plug to use for this motor. J8C is a hotter plug the J4C. Correct me if I'm wrong. I want to make sure I get the right plug and not get strained out on the Chesapeake Bay while Crabbing. Also I will be doing a lot of slow Trolling. Should I still use the J4C's or should I go a little hotter, maybe the J6C's? Thanks for everyone’s help.

 

[CATransplant]

Re: Champion plugs for 70 25hp, J8C is called for

The catalog is wrong. J8Cs are too hot for your little motor. Not good. The J4Cs are fine. If you're going to be doing a lot of trolling, gap them at .040" instead of .030", or at .035" if you want to compromise.<br /><br />If you're going to be trolling mostly, then J6Cs are a good choice, but if you're going to be mixing it up, I'd use the J4Cs.<br /><br />Also, buy two sets. Put the second set in the toolbox you carry on the boat, along with a spark plug socket and rachet. You should always carry a spare set of spark plugs.

 

[Joe Reeves]

Re: Champion plugs for 70 25hp, J8C is called for

You can use either the J4C or the J6C Champion spark plug. The J6C may provide a slight increase in performance. Do not use ths J8C as that plug is too hot for that engine and will result in piston damage.

 

[fishonboat]

Re: Champion plugs for 70 25hp, J8C is called for

Thanks for the Reply’s. I actually have another problem. I did find the J4C's at BoatUS yesterday. Anyway I took it out yesterday Evening for a trial run and this is the first time out with a new head gasket and a thread insert to replace one of the striped spark plug holes. After returning home and giving the motor time to cool I started to remove the spark plugs to check for any signs of water to make sure I had a good seal with my new head gasket and when I removed the Spark plug the Thread insert came out with it. I have started the motor in the drive way on the garden hose and pulled the plugs and had no problems with the insert then but this is the first time driving it hard after the insert was installed. This is the type that uses a substance similar to Locktight. Any thoughts as to how I can keep this thing in. Also the insert is still stuck to the plug. So what I have done is applied more of the substance that the insert kit came with and I screwed the plug back in the hole with the insert still attached. I’m hoping to give it a couple of days to dry and I will try to unscrew the plug and see if it will come out and the insert stay in. If this doesn’t work what are your thoughts on applying some JB weld around the threads on the insert and screw it back in.? Thanks for the help.