Spark plug question

[afaust]

Hi,

Searched the forum, never really found an answer. My 87 mariner OB204751 has been bogged down.... I suspect the carbs, however one little detail bugs me and I'd like to know if it makes a difference. According to all searches I've done, the correct plug is a gapped plug, however the ones in the motor right now are gapless. could this cause a problem? I was able to run the motor on the water once at WOT for 15-20 min before it started bogging down.... Now at full throttle, I don't have any power whatsoever....

Allan

 

[Alumarine]

You don't give a HP but here's a list of plugs for the 87 model year.
http://www.iboats.com/Mariner-NGK-S...4298718--session_id.111946692--view_id.669911

 

[afaust]

For the response, it's a 45 hp 4 cylinder 1987 mariner. According to the chart, there is only the 454 that is gapless... According to the info I found, it's a standard auto plug that I need, which makes me ask what I do need, and if the gapless could cause an issue with the motor or not. I want to know if it makes a difference and why?

 

[Faztbullet]

OEM plug is a gapless NGK BUHW-2

 

[afaust]

That is what I believe is in there, thx.... I've been reading conflicting information, so I wanted to be sure that it wasn't an issue.... Eliminate the obvious, and work out the rest.

 

[Dekker500]

To eliminate conflicting information, go to the source: https://webapps.brunswick.com/literature/literatureSearch.do which is the Mercury parts catalogue. Type in your Mercury/Mariner serial number, and it'll give you specs on your engine and you can flip through the parts pages. It confirms Faztbullet's response on the plug type.

 

[afaust]

Thx, it's appreciated.

 

[60sboater]

They are usually called perma gap or surface gap instead of gapless. They shoot the spark sideways or laterally from center to the outer/ground section.