plug gap and fouling

[rednight]

Trying to figure something out, and the archives aren't helping. <br /><br />Will a wider gap (.040 instead of .030 on my '79 115hp) prevent fouling, or just allow spark despite fouling?

 

[JB]

Re: plug gap and fouling

What engine, Rednight?<br /><br />Are you getting fouling? What plugs are you using? How do you use the engine?<br /><br />Fouling is when deposits prevent spark.<br /><br />Let us know.

 

[rednight]

Re: plug gap and fouling

The engine is a 1979 V4 115hp, fairly new to me. Last summer's plugs came out uniformly black, and new ones I just put in are showing signs of fouling to come (black specks) after one afternoon, half trolling, half planing. <br /><br />So I increased the plug gap to .040. Standard Champion l77jc4. <br /><br />The engine has been dying at idle from time to time, particularly when cold. Thermostats are new.

 

[angus63]

Re: plug gap and fouling

Opening to 0.040" gap will lengthen the number of hours you can run at low rpms before fouling affects the spark. If fouling is a regular issue, might want to use synthetic 2stroke oil and adjust carb mixtures if it's a bit rich.

 

[rednight]

Re: plug gap and fouling

Sounds like good advice about the oil. Unfortunately, I don't think the jets are adjustable on this carburetor -- so we'll hope the oil solves the problem.

 

[JB]

Re: plug gap and fouling

You might try a hotter plug. <br /><br />Oil and mix are not as much of a factor as plug temperature in allowing deposits to form. No plug is perfect at all speeds. The L77J4C is a compromise for wide range operation. The L77J6C should work better at low speeds, but not as well at high speeds. Gap it at .030". <br /><br />Good luck.