Question: Spark Plugs

[petey305]

Hi Everyone,<br /><br />I starting the rebuild of my 1960 Evinrude Lightwin 3hp. <br /><br />I noticed something strange about the spark plugs. The plug for the first (top) cylinder has a thicker threaded portion then the second (lower) cylinder. I looked through the manual and it said nothing. As this is my first Outboard rebuild...I am puzzled since the spark plugs are both Champion Spark plugs with the same number (J4J I belive?)<br /><br />Is this normal...do they sell them in pairs or something. If it is normal...why would they do this?<br /><br />Thank,<br /><br />Petey

 

[petey305]

Re: Question: Spark Plugs

^bump

 

[grandx]

Re: Question: Spark Plugs

Are you saying that the top and bottom plugs are not interchangeable on your engine? Both plugs have the same model #? Never heard of anything like this. Possibly the largeer hole was stripped at one time and an oversized hole was threaded to accept an insert/helicoil, can you tell if the larger one indeed has an insert around the original plug?

 

[petey305]

Re: Question: Spark Plugs

Right...the top and the bottom are not interchangeable. I don't believe there was any insert or anything around the plug...but I will check later tonight.<br /><br />I am as confused as anyone.<br /><br />JP

 

[wilde1j]

Re: Question: Spark Plugs

Top cylinder probably had a Helicoil installed improperly. Champion doesn't make different J4J's. The Helicoil came out with the plug.

 

[seahorse5]

Re: Question: Spark Plugs

Years back there was a thread repair kit called a Keen-sert (sp). It was a threaded tube with a flanged end by the plug gasket, that needed a lot bigger hole than the diamond shaped Heli-Coil threads. It was not recommended by OMC at that time since it could come out of the aluminum head.<br /><br />To get by, see if you can remove it from the plug and install it on a new plug. The best bet, though, is to find a good used head.