spark plug discussion

[WetRaider]

OK ... the thread 87 CVX16 has introduced spark plugs ...

Got me thinking, & looking things up.

Pulled the plugs (installed last summer by Water's Edge Marine in Johnston, IA) from my Merc 1150 - they are Champion L76V plugs.  

According to this cross reference chart, http://www.sparkplug-crossreference.com/convert/CHAMP_PN/L76V , the NGK equivalent is a BUHW.  I came across a Mercury reference chart that identified the BUHW for my 1150 application as well.

NGK's website identifies the BUHZW for my 1150 application.  Of course, none of these charts take into consideration the year, simply the model number of the motor.

Last year I had problems with being at WOT and quickly losing power ... the engine would cut out almost as if I were running out of fuel.  Had talked with Rich about it, too, and I remember him saying he had the same experience ... if you backed slightly off WOT, no problems.  Other times it would run WOT just fine (but still not fast, only 4800 RPM - tach wired to rectifier, not switch box)

In wondering the difference between the BUHW & BUHZW, I came across this thread.  I found it interesting.
 
http://forums.iboats.com/showthread.php?t=534601

Not sure that this would be why I had WOT issues at all.  But it seemed informative.  I messaged Rich privately & then decided I want to hear anyone else's opinion.  Was thinking it wouldn't hurt to pick up a set of plugs to have on hand, just-in-case.  If these BUHZW seem the way to go, I don't have anything to lose.  Chime in with your thoughts ...

[badgercarlson]

I've been using NGK BUHW in my 1977 1150 for many years with no problems. I actually called the Mercury Marine corporate office in April of '96 (I wrote it down in my owners manual) and was told to use the BUHW instead of the Champion L76V because it gives longer service life. I had a problem exactly like you are describing and it turned out to be the fuel pump. I have bought new BUHW's and Terry, a member of our group, gave me quite a few slightly used BUHW's at Red Wing a few years back. All have worked with no problems.

[David CVX-16]

The NKG sparkplug application book for outboards list NGK plugs that are not common. I suppose you would order that exact sparkplug online from a big distributor. When I went to get NGK surface gap plugs for the 1985 Johnson 115, the NGK application listed a BUHXW-1, which Fleet Farm did not have, but the Champion plug of L78V ( the surface plug to use from the Johhnson owners manual) crossreferenced to BUHL2, which I bought. Now I am wondering if there is a difference between the two plugs.

Here the the NGK link:

http://www.ngksparkplugs.com/part_finder/watercraft/make.asp?table=toutboard

[Retro Performance]

I have been dealing with Mercury Marine for 35 years....have never seen an inline six lose top end from using non resistor plugs. I had a long time friend and Mercury field service rep in the store today working on an Optimax......I will be hearing from him again on Monday and will try to remember to ask his opinion... I would say he is the best In Line six mechanic in the country..it seems to me the Z series plugs came out in the 90's....I seem to remember they were required by legislation in some countries (Canada the only one that we were concerned with at the time) because of the advance and use of microproccessors and electronic control systems.....the resister plugs were (are) required (by law I think) to help control Electro magnetic interference and radio frequency interference to these surrounding systems.  Again that is my memory, may be all wrong but that is what I remember and it does make for a good story right? LOL

[wexrocks]

Losing top end sounds alot more like a fuel issue as was mentioned... has your pump/lines/filters been checked and replaced/serviced lately?

Spark plugs are like oil, everybody has different opinions based on experience, and will stand by whatever they've had luck with. understandable. One thing to keep in mind is, for every application, there is a range of plugs that will fit, with different "heat" ratings. a "colder" plug will resist fouling better, while a "hotter" plug will potentially provide a little more performance (usually unnoticeable in most cases) but could foul easier and possibly not last as long. much like oil, there is alot of room for debate, and numerous points for every opinion. I'd go with whatever has worked well for other guys with the same style motor, with the same general amount of hours on the motor, and who use similar fuel/oil combinations. if you're getting different results than everybody else, may be a carb/fuel issue instead.

[Retro Performance]

David, L78v should cross to a BUHW-2 I think......L76V and BUHW'S are cooler heat range ....L78V and BUHW-2 are hotter....was BUHL2 a misprint or is there such a plug? Next time you are at the store we can look at the charts and compare the different plug numbers.

[David CVX-16]

Yes, it should have been BUHW-2.

Went back to Fleet Farm and bought a set of L78V. Now I have a set of BUHW-2 and L78V.