Evinrude Motor help Spark plug 15 horse outboard motor 1990?

Question

What size gap on the spark plug is it suposto be?

Answer 1

Not critical. 25-30thou.

Answer 2

I would call your local boat dealer to be sure. It may depend on the type plug you using. For example; Champion QL77JC4 or L77JC4 gapped at .040

Champion QL78C gapped at .030

This "May" be the settings for sustained low speed operation. Also, these numbers may be old and need cross referenced.

For sustained high speed operation you may use the non-adjustable gap. which may be Champion QL78V, QL16V or L78V.

So, the best way to be sure and know what plug you need to use, gap or non-gap, I would call my local dealer. Usually the parts department can help.

Answer 3

snaggels is right, unless you have the exact make and model manual, which may suggest a certain plug and gap