Surface gap spark plugs

[Wilson]

Changing the plugs on my older mercs.
Got a email that said to use a surface gap?
Any help on what that is . Is that basicaly useing them right out of the box or?
if I do gap them what is the gap?
Motors are 2 stroke around 1993.


Thanks for any help.


Wilson

[fishkisser]

Surface gap plugs, which provide a solid-state medium for the electrons to migrate across, generally allow electron flow, regardless of spark voltage...
However, they do not allow the air/fuel ratio 360 degrees of contact area with the migrating electron as is accomplished with an open gap type spark plug, but rather only 180 degrees...
This is because 50 percent of the electron path is shrouded in the solid state medium...
Like platinum and split electrode ignition plugs, they mask a problem inherent in weak ignitions...
Some have 2 electrodes , some have 4 ...Here a picture to illustrate how they look ...
http://www.powersparks.co.uk/images/plugs/closeplug.jpg

[baitsauce]

fishkisser you are smart. Glad someone knows about this 'cause I ain't no dummy about engines but I have never heard of "surface gap spark plugs". But I have seen spark plugs like the one in your attatchement. Good plugs if you want to spend the extra cash.

However, your discription sounds a lot like an igniter for a jet (aircraft) engine.

[fishkisser]

fishkisser you are smart. Glad someone knows about this 'cause I ain't no dummy about engines but I have never heard of "surface gap spark plugs". But I have seen spark plugs like the one in your attatchement. Good plugs if you want to spend the extra cash.

However, your discription sounds a lot like an igniter for a jet (aircraft) engine.

Yea ... I use a lot of big words sometimes to describe something simple ...:hoboy:
Its hard to be a black hole of semi useless facts and trivia ...
Besides being a wizard at Googling information on the world wide web ...:D
I try in the future to keep it simpler but no guarantees ...:laugh::laugh::laugh:
Surface gap plugs are the bomb for ignitions that drop voltage in higher rpm's such as conventional inductive ignition systems ...

[KingSalmonBoy]

Wilson, after reading this post, I have learned something new thanks to Fishkisser. I wonder if the email you were referred to was referring to a NGK BUHW-2 or a Champion L76v. I have the L76v's on my 1997 75HP Mercury Force (possible variant of surface gap plug). No gap adjustment on these plugs.

[Seahare]

While it's true that there's not an adjustment on the gap of surface gap plugs, they do have different gaps as manufactured.

An BUHW has a .050 gap while a BUHW-2 has a .071 gap., for instance.

What model/serial no. are your mercs. Many Mercs use conventional electrode style plugs and if surface gap are used they'll run poorly because they don't have the ignition system needed to support them.

You should refer to the spark plug manufacturers catalogue or Merc. for the proper plug. Substitution can ruin an engine.

[Wilson]

Turns out my info I recieved was wrong.
My mercs take ngk bp8h-n 10, with a gap of .040. I have no idea how surface gap came into play, but I did learn a few things from you guys!


Thanks for all the help.

Wilson

[huntinwithlabs]

2 years ago I purchased a used 50hp force. I picked up some extra plugs at the same time. I hadnt seen surface gaps before and when I opened the box I thought I had defective plugs. Luckily someone educated me before I tried to return them.:D