spark plug gap on merc 90

[lincolnnellie]

I have a merc 90, I believe it is somewhere around 1982 - 1984. I don't have a manual for it and need to know the proper spark plug gap. Thanks!

 

[Barnacle_Bill]

Re: spark plug gap on merc 90

Use NGK BU8H. They are gapless and much better for a Merc.

 

[Texasmark]

Re: spark plug gap on merc 90

Not sure surface gaps will work for that vintage of engine. Is it magneto powered?

Surface gaps carbon track across the insulator. Ignition systems that use them have to deliver high voltage very rapidly (like 10's of microseconds) so as to get the "shot" before it bleeds off across the track on the insulator.

I had an '89 tower with solid state ignition and it had them. I had the boat 7 years. Changed them out after 1st year and never again....didn't seem to have to.

Mark

 

[Barnacle_Bill]

Re: spark plug gap on merc 90

I used them on a 83 150 and they worked fine. Dealer said thats what his book said to use.