Determining spark plug gap

[gsonnier]

I have a 93 25HP Merc. Trying to determine the measurements for gapping spark plugs. I finally broke down and bought a Seloc manual for my 1993 25 Mercury. I see a chart for "Piston to cylinder clearance" and "Piston Ring End Gap", but no dimensions for 6-25 HP's are given. It just says "N/A".<br /><br />Where else can I find this or does it matter that I gap them? Thanks.

 

[wilde1j]

Re: Determining spark plug gap

Do you have the motor torn down? If you don't, why do you care about ring gap or piston clearance?

 

[rickdb1boat]

Re: Determining spark plug gap

Look in the front of the book. Should be under "Engine Specifications" or "Tune-up Specs". But in case you can't find it: NGK Plug # BP8H-N-10 Gap.040 (The Gap will be the same, no matter what brand of Plug you use)

 

[gsonnier]

Re: Determining spark plug gap

Thanks for the info and direction Rickdb. I must have read right past the most important part.

 

[HowieDean]

Re: Determining spark plug gap

Also keep in mind that the recomended gap is in the plug number BP8-N-10 ,, that 10 is 1.0 mm or .040 inch... If you want to know what all the letters and numbers in the plug number mean click here... NKG sparkplug info

 

[gsonnier]

Re: Determining spark plug gap

Do the plugs come out of the package already gapped? In the past I usually drop my rig off twice a year for tune up. A couple of times I ignorantly replaced the plugs myself with new ones right out of the package. From what I've heard, I can burn up an engine without the proper gap. I guess I just got lucky?

 

[rickdb1boat]

Re: Determining spark plug gap

You need to Gap them, as you never know what the factory has them at.