Mariner Sparkplugs Again

[dish]

Has any one used the NGK BUHW-2 sparkplugs on an early 80s inline 115hp mariner????? I just want to try a hotter plug for idling.

 

[dish]

Re: Mariner Sparkplugs Again

Any one?????

 

[Mi duckdown]

Re: Mariner Sparkplugs Again

It will also be hotter at full throtle. Be careful.

 

[dish]

Re: Mariner Sparkplugs Again

Hot enough to do any damage at wot????

 

[Bondo]

Re: Mariner Sparkplugs Again

Ayuh,... Are they fouling out at idle,..??

Sounds like yer trying to fix a Carb issue by changing the sparkplugs....

 

[redjmp]

Re: Mariner Sparkplugs Again

If you are fouling plugs at idle, it might be due to the seals around the spark plugs on the cover plate are leaking a little and dripping down on the plugs thereby cooling them off a little.
Run the motor in the water under load with the cowling off to check.
You'd probably have some whiteish deposits on that cover plate if that was the case.

 

[dish]

Re: Mariner Sparkplugs Again

No,the plugs arnt fouling and the carbs are perfect.I do alot of idling and i get an oil line on the transom.The buhw plugs from what i understand are designed for high speed operation,correct me if im wrong.So i was thinking maybe a slightly hotter plug might fix the oil mark.At 3000rpm i get 25knots and at 5500 i get 48 knots so i cruise at 3000rpm and rarely go any faster so the hotter plug i think shouldnt affect wot because i never hit it.Whats do you think???????

 

[redjmp]

Re: Mariner Sparkplugs Again

Remember that these inlines 6's really are race motors that don't like being idled too long.
There is no thermostat for starters so combustion cylinder temps can vary quite a bit especially at idle and in colder water...
The oil line is from running premix. At idle speed you only need about 100 to 1 gas to oil ratio but are feeding it 50 to 1 ( assuming you did the smart thing and turfed the autoblender) so there will be some unburnt oil.
Better safe than sorry.
I have run buhw2's before with no problems but I don't run at wot for very long.
Those surface gap plugs will never get so hot as to cause detonation imho but I don' think that they will clear up your unburnt oil situation especially if they are not fouling...

 

[dish]

Re: Mariner Sparkplugs Again

Your probably right,its running fine so i think i might just put up with a bit of an oily mark at idle.I was wondering if this motor used to have the auto blend.Were they abit of a problem back then?

 

[redjmp]

Re: Mariner Sparkplugs Again

Yup those old autoblenders were bad on 2 accounts.
First off they were slow to respond. When you hammer down from idle is when you need the 50 to 1 ratio the most due to the extra load of getting out of the hole but it takes around 15 seconds for the extra oil to make its way into the cylinders.
I actually did the math on another thread to highlight my point that it does take that long.You can search for it if you like.
Secondly is the fact that they will eventually fail and when they do, they will starve your engine for oil and will ruin your powerhead in the process.

 

[dish]

Re: Mariner Sparkplugs Again

Sounds like they were as reliable as the old vro pumps.Although i am really confident in the oms pumps as long as your alarms are good.Another question i have is i am getting 15.2 volt out of the rectifier at high rpm.The po put i new stator on and im not sure if its the old 9amp or 16amp.Should i replace the rectifier with a regulator???Is 15.2volts enough to boil the battery?

 

[redjmp]

Re: Mariner Sparkplugs Again

That is a sign your battery is on the way out.
They didn't bother putting in regulators because a good battery will act like one and soak up any excess voltage.
15.2 is just barely good still but when it gets to 16 or 17.....

 

[dish]

Re: Mariner Sparkplugs Again

The battery is a deep cylcle and looks pretty old.So you think a new battery will bring the volts down to around 14 even with the output not being regulated.

 

[jeffersondodson561]

Re: Mariner Sparkplugs Again

FYI you should not use Deep Cycle batteries with an unregulated charging system, infact deep cycle batts are not good for starting batteries.

 

[dish]

Re: Mariner Sparkplugs Again

Yeah i know mate.The boats only new to me so im in the process of customizing it to suit my own needs.Im adding a twin battery setup so i will keep the deep cycle for accessories.I didnt think an unregulated system would put out that much voltage.