correct plug type

[quazerboy]

Please could you confirm the correct plug type for my 1972 18hp Evinrude. I've just bought some Champion J6C's but they seem to be a shorter reach than the ones that are in it already, but that's not to say the ones that are in it already are the right ones! I don't think any damage has been done to the engine and it does run!<br />Thanks<br /><br />Lee

 

[kirkland]

Re: correct plug type

Champions site says to use<br /><br />Champion Traditional spark plug 871 RJ8C .030 "Q-Series" inductor types (used in Copper Plus & Premium Stainless) are the only OMC approved replacement plugs for engines specified. Use of other types may cause engine misfire. For Commercial service use 876/QL16V.<br /><br /> OR<br /><br />Champion Traditional spark plug 841 J8C .030 "Q-Series" inductor types (used in Copper Plus & Premium Stainless) are the only OMC approved replacement plugs for engines specified. Use of other types may cause engine misfire. For Commercial service use 876/QL16V.

 

[angus63]

Re: correct plug type

Chart calls for J4C Champion gapped at 0.030".

 

[kirkland]

Re: correct plug type

Wonder why Chapmions site differs from chart ..??

 

[Dhadley]

Re: correct plug type

Ever since Champion was taken over (by Cooper & Fedral Mogul, I believe) that has happened. Their recommendation is not necessairly what the OE recommends. Go by your engine manufacturer.

 

[CATransplant]

Re: correct plug type

If you do a lot of trolling with that 18, try J6C plugs. They're one grade hotter.

 

[kirkland]

Re: correct plug type

Live and learn...sorry for misleading you Lee ..it wan't intensional...listen to the experts...

 

[quazerboy]

Re: correct plug type

Thanks Guy's, and DEIFan there's no need to apologise, it is confusing trying to get things right, particularly in the UK, where we do not have access to the same things as you do in the states, and everything is twice as expensive! Which is what makes this site such a godsend.<br /><br />Stupid question but.. can you confirm that all J6C's have the same thread reach, I'm still a little concerned that the ones I've just bought are too short in comparison to the ones I'm taking out. These plugs cost $10 each here, so if they are not right I'd like to swap them rather than use them!<br /><br />Lee

 

[Dhadley]

Re: correct plug type

No need to apologize DEI. Trust me you arent the first person that happened to. Years ago we used to use the Champion book as much as the OE guide. I cant tell you how many times a motor has been rebuilt and then had issues from the wrong plug being used. Then the debate is on to see who stands behind it.<br /><br />Lee, what plug was in it before? I'd be more afraid of the longer reach than the shorter one. We have not heard or seen anything wrong with using the J6C's in that motor.

 

[seahorse5]

Re: correct plug type

Originally posted by Lee Harris:<br /> Stupid question but.. can you confirm that all J6C's have the same thread reach, I'm still a little concerned that the ones I've just bought are too short in comparison to the ones I'm taking out. Lee

The letter J in a Champion plug means that it is a 14mm thread with a 3/8" reach. Any other letter would be the wrong plug.

 

[quazerboy]

Re: correct plug type

Dhadley, the plugs that are in at the moment are the ngk equivalent of whatever plugs were in it when I got the engine, I just went to the Chandlers with the old plug and they gave me the same, but the thread reach is about double the J6c, hence my concern. But, fortunately, nothings hit the plug as the engine does still run and I would assume that the first thing to hit would be the electrode, which would then bend and short out. <br /><br />Seahorse, thanks for the info, it does amuse me how you guys of=ver the pond mix metric and imperial. I do the same even though I grew up in an exclusivly metric school system I still measure things about 37" and 4mm.<br /><br />Lee

 

[Dhadley]

Re: correct plug type

I'd really advise getting those NGKs out and getting the Champions in.

 

[quazerboy]

Re: correct plug type

It shall be done. Do you think that will help with my fairly rough low speed running?