Plugs for '71 Rude 40hp Ski Twin

[foxjohnc03]

I am trying to find out what kind of plugs to put in my old 40hp rude. It currently has Champion J6C plugs but I thought that it took J4C's? Which if either is correct? Thanks.

 

[rickdb1boat]

Re: Plugs for '71 Rude 40hp Ski Twin

J4C if you run normally. J6C if you troll alot. The J4C should be fine for all around use and that is what is recommended, though. Gap is .030 BTW...

 

[foxjohnc03]

Re: Plugs for '71 Rude 40hp Ski Twin

Have a pair of J8Cs on the table. Would they be able to run for the weekend? Dont want to burn anything up though. I assume that the 4,6,8 are the heat rating. Is the higher # hotter or colder? Just curious.

 

[Paul Moir]

Re: Plugs for '71 Rude 40hp Ski Twin

Hotter. J8C's are too hot and you'll risk preignition and piston damage with them.