surface gap plug or electrode plug

[tacodads]

I have a 97 75hp 2 stroke Mercury that seems to be missing. can I trade the surface gap plugs for electrode plugs? would that make a difference in slow no wake running? It also runs very rough when I throttle up. Thanks!

 

[Texasmark]

Merc lists 2 plugs, both NGK in the serv. manual for the 3 cyl engine starting in 1996: BUHW-2 or surf gap BUZHW-2. For the gapped version, NGK pre gaps their plugs per the part number so just unpack and install.

 

[Chris1956]

Isn't BUHW-2 surface gap also?

I would recommend you find a Mercury OB approved electrode-type, before you substitute.

I also doub't the spark plug style is causing your issue.

 

[Texasmark]

Isn't BUHW-2 surface gap also?

I would recommend you find a Mercury OB approved electrode-type, before you substitute.

I also doub't the spark plug style is causing your issue.

May be. NGK online manual could answer that. My last manual, same as this one but not revised in 2015, listed 2 plugs for the 3 cyl engine which I had at the time. I ran both, one SG and the other gapped. I suspect that's the same here...but I haven't tested the water. Online data tells me that the SG is better for cool running for long periods of time....I relate that to a friend who had a hunting cabin on the Gulf Coast 40 miles from the nearest launch site. There's a sad story ending to his cabin and what he did to his boats getting there and back.

 

[Texasmark]

NGK catalog, Page 241 states that both are surface gap. Interesting in that from the original posting of the Mercury serv. manual for '96 and newer engines, a manual I had when I had a 2002 90 hp, they dropped the conventional gapped plug from the lineup and put 2 different SG plugs. The optional included the Z, for special design...who knows what triggered that addendum.

B= 14mm thread, 20.8 mm nut
U= Surface or semi-surface discharge
R= If resistor type, R would be inserted here
H or HZ, H= 12.7 mm thread reach......Z = special design
W= Tungsten electrode
-2 has to do with the actual surface gap....width not posted; both have the same gap.

 

[tacodads]

Thanks guys.