Alternate for a surface gap spark plug???

[MikDee]

Is there an alternate standard gap spark plug of the proper heat range, that can be used in place of the surface gap plugs as found as standard orig. equipment in the Force outboard's?

These surface gap spark plugs have a large fixed .050" gap, and I see that a lot of the Force motors are having problems with losing spark on one, or more cylinders, usually due to a portion of the stator burning up, is it because of this large spark plug gap? It's beginning to become a theory of mine after recently having, & learning about the workings of Force motors.

surface gap spark plug info: http://www.championsparkplugs.com/more_info.asp?otherMotiveID=12338&pid=4430

 

[CharlieB]

Re: Alternate for a surface gap spark plug???

'Standard' electrode plugs have/are being used in place of surface gaps plugs but only in SOME ENGINES, not all.

Adequate piston clearance is MANDATORY to collision prevent damage from/with the spark plug electrode.

Also, some engines require the timing to be retarded to compensate for the accellerated burning speed caused by the relocated ignition point within the combustion area.

DO NOT make the switch without very careful consideration, dire consequences are possible.

Surface gap plugs are and have been used for a very long time.

 

[MikDee]

Re: Alternate for a surface gap spark plug???

'Standard' electrode plugs have/are being used in place of surface gaps plugs but only in SOME ENGINES, not all.

Adequate piston clearance is MANDATORY to collision prevent damage from/with the spark plug electrode.

Also, some engines require the timing to be retarded to compensate for the accellerated burning speed caused by the relocated ignition point within the combustion area.

DO NOT make the switch without very careful consideration, dire consequences are possible.

Surface gap plugs are and have been used for a very long time.

1) I've never heard of an engine made that doesn't have piston room for conventional spark plugs? as long as they are the correct heat range, thread type, thread length, and the right seat type.

2) I don't think this is the case on a stock motor, maybe so on racing engines?

3) I had a 1969' Evinrude V4 115hp that gave you an option of conventional spark plugs, or an equivalent surface gap plug number, I used both in that motor, and found no advantage with the surface gap plugs, so I know they've been around a long time.

IMO surface gap plugs with their large fixed gap put alot of stress on any ignition system, I was only looking for a conventional spark plug replacement in the correct heat range that will not do this.

 

[CharlieB]

Re: Alternate for a surface gap spark plug???

I've made the change in a LOT of engines but I maintain an absolute minimum of .o5o piston to ground electrode clearance.

There are a number of Merc, Mariner and Force's with high dome pistons that do not have enough clearance and I am forced to remain with the surface gap plugs.

Not all have the .050 surface gap. Get your hands on an NGK plug book and look at all of the surface gaps made, different gaps, and different heat ranges.

I vary plug style (surface gap, conventional, protruded tip) and heat range to match declining compression and/or the individual owners operating habits, I may vary timing 2 degrees depending upon the engine and individual. I may tweak carb float levels, again depending upon the engine and individual.

 

[MikDee]

Re: Alternate for a surface gap spark plug???

I've made the change in a LOT of engines but I maintain an absolute minimum of .o5o piston to ground electrode clearance.

There are a number of Merc, Mariner and Force's with high dome pistons that do not have enough clearance and I am forced to remain with the surface gap plugs.

Not all have the .050 surface gap. Get your hands on an NGK plug book and look at all of the surface gaps made, different gaps, and different heat ranges.

I vary plug style (surface gap, conventional, protruded tip) and heat range to match declining compression and/or the individual owners operating habits, I may vary timing 2 degrees depending upon the engine and individual. I may tweak carb float levels, again depending upon the engine and individual.

Wow, ok thanks for the info, I was referring to an 89' Force 125hp outboard, would you know if I could put conventional plugs in this motor? otherwise I'll take all that into consideration if I decide to change from a surface gap.