Author Topic: Not Easy to Choose Spark Plugs for Outboards These Days  (Read 446 times)

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Offline David CVX-16

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Not Easy to Choose Spark Plugs for Outboards These Days
« on: November 05, 2017, 03:00:36 PM »
I change spark plugs each year, with all due respect to Jerry G. But it is getting harder and harder to make the decisions. The owners manual recommends Champion QL77J4 or L77J4 for a 1985 115 HP Johnson. But do I need the resistant QL77J4 at $1.00 more per plug? Then there are the QL77JC4 and the L77JC4. What about gap versus the rim fire Champion QL78V? Then the recommended gap was changed from .040 to .030 years ago. Doug C uses iridium plugs, and there is a cross reference from QL77JC4 to an iridium plug. Today I when to Mills Fleet farm and bought four QL77JC4 plugs at $2.98 each. But I had to look at 20 clear plastic covered packages over the spark plugs to get four that had the gap centered over the firing point, most were off center, and maybe that does not matter. What should be simple gets to be not so simple, but I'm not complaining.   

http://www.sparkplug-crossreference.com/convert/CHAMP_PN/QL77JC4
« Last Edit: November 05, 2017, 03:09:02 PM by David CVX-16 »
David
87' CVX-16, 85' 115 HP Johnson, 58.8 MPH GPS w/ 23" SRX Prop
88' 115 HP Mercury (Backup Motor)

Offline Hyperacme

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Re: Not Easy to Choose Spark Plugs for Outboards These Days
« Reply #1 on: November 06, 2017, 07:56:01 AM »
Are the " iridium plug's" what they use in new cars that can go 100000 mile between changes ?
I've been running the NGK BUHW surface gap plugs, seem to work but were about $9 per plug ...
Gregg
'76 CV16

Offline David CVX-16

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Re: Not Easy to Choose Spark Plugs for Outboards These Days
« Reply #2 on: November 06, 2017, 12:50:57 PM »
Iridium plugs last longer than platinum plugs. The owners manual for my 2002 Toyota suggested changing plugs at 120,000 miles, but I would change them about 60,000 miles. Yes they are more expensive. Check Fleet Farm for your NGK BUHW plug price. Their price may be much less than $9.
David
87' CVX-16, 85' 115 HP Johnson, 58.8 MPH GPS w/ 23" SRX Prop
88' 115 HP Mercury (Backup Motor)

Offline Plugcheck

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Re: Not Easy to Choose Spark Plugs for Outboards These Days
« Reply #3 on: November 06, 2017, 01:18:54 PM »
I have several plug manufacturers that I like, champion is not one of them.  I prefer Bosch for street, ngk for 2 strokes.  Given lean burn and electronic controls, most street type plugs last for years, some up to 100k miles.  Carb'd engines require more frequent changes.  Overall I stick mostly with manufacturer recommend plugs, unless I've made upgrades.  Gap is critical, take the time to vary it somewhat, if performance tuning.  I always keep a spare set sealed in plastic for all my outboards.  Once a plug "glazes" it's just not going to be right again untill it's blasted, cleaned, and re gapped. 
Michael
1979 CVZ-18 388 CI Vortec Mouse
1980 CVX-16SS 140 Mercruiser
1979 CVX-16 Johnson 175
2002 Bennington 2275CC 90 Mercury
1985 Intimidator project, gps 85 mph (on trailer)
1989 Lowe 200 Redneck fishin Toon

Offline V153

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Re: Not Easy to Choose Spark Plugs for Outboards These Days
« Reply #4 on: November 06, 2017, 06:39:34 PM »
Back when I had money tried every plug on the market. Nowadays I run the factory recommended Champions. (In a V4 Crossflow.) Surface gap(s) seems to work just fine for me?
'81 Baja 15SS_140 Frankenrude_66.7 mph
'70 something SpeedCraft_(Allison 16R Clone)_Restoration In Progress


WALK TALL AND CARRY A BIG BILGE PUMP

Offline David CVX-16

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Re: Not Easy to Choose Spark Plugs for Outboards These Days
« Reply #5 on: November 07, 2017, 06:56:57 AM »
After a lot of research on sparkplugs for the V4 Crossflows, the consensus was to use the Champion plugs. I asked Jerry S whether to use the gap or the surface, and he said the gap because the fire was deeper into the combustion chamber. My owners manual says gap for lower speed use and the surface for higher speeds.
David
87' CVX-16, 85' 115 HP Johnson, 58.8 MPH GPS w/ 23" SRX Prop
88' 115 HP Mercury (Backup Motor)

Offline Diamond Chad

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Re: Not Easy to Choose Spark Plugs for Outboards These Days
« Reply #6 on: November 07, 2017, 07:37:49 AM »
explain the difference between the gap and the surface for those of us that don't know the difference.
87 CVX18 5.7
88 CVX16 115 Merc
57 Dunphy Imperial Musky - 57 Golden Javelin
01 Malibu Sunsetter 21 LSV 340 EFI

Offline Hyperacme

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Re: Not Easy to Choose Spark Plugs for Outboards These Days
« Reply #7 on: November 07, 2017, 12:33:32 PM »
NGK.com / Spark Plug Terms
https://www.ngk.com/glossary/8/spark-plug/S


Surface gap ...





Standard spark plug ...

« Last Edit: November 07, 2017, 12:41:37 PM by Hyperacme »
Gregg
'76 CV16

Offline David CVX-16

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Re: Not Easy to Choose Spark Plugs for Outboards These Days
« Reply #8 on: November 07, 2017, 01:06:34 PM »
David
87' CVX-16, 85' 115 HP Johnson, 58.8 MPH GPS w/ 23" SRX Prop
88' 115 HP Mercury (Backup Motor)

Offline Diamond Chad

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Re: Not Easy to Choose Spark Plugs for Outboards These Days
« Reply #9 on: November 07, 2017, 02:47:07 PM »
Is there a way to measure and set a surface gap plug?  Kind of looks like you just buy em and use em.
87 CVX18 5.7
88 CVX16 115 Merc
57 Dunphy Imperial Musky - 57 Golden Javelin
01 Malibu Sunsetter 21 LSV 340 EFI

Offline Rich_V174SS

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Re: Not Easy to Choose Spark Plugs for Outboards These Days
« Reply #10 on: November 07, 2017, 04:32:12 PM »
Nothing to set on a surface gap plug, they are what they are.
1967 V174 Crestflite SuperSport Modified
1987 Mercruiser 190 3.7LX/Alpha One

1970 V176 Swinger
1983 Mercury 115

Offline Hot Rod Roy

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Re: Not Easy to Choose Spark Plugs for Outboards These Days
« Reply #11 on: November 08, 2017, 01:00:44 AM »
I was warned by a very experienced 2 stroke outboard shop that if surface gap plugs are recommended for my Evinrude 115, that's what I should use for the reliability of my power pack.   I was surprised to find the correct plugs at my local O'Reilly's Auto Parts, at about half the price of a marine store.

 8)
1950 Chris Craft/Mercury
1974 CV-16/Evinrude 115

Offline Hyperacme

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Re: Not Easy to Choose Spark Plugs for Outboards These Days
« Reply #12 on: November 08, 2017, 09:14:04 AM »
My motor (1989 Mariner 115) has oil injection, which varies the amount of oil depending on throttle setting, 100/1 at idle to 50/1 at WOT, which would help plug fouling ...
But also has 2+2, which cuts out two cylinders from idle to about 2000 RPM's.
I'm thinking Merc knowns more about this motor then anyone would, and if they say "NGK BUHW" that what I'm going to use ...

From what I'm reading surface gap are recommended for higher speeds.  Guess I run higher speeds then your average fishing boat / pontoon / ski boat ... Maybe ...
Gregg
'76 CV16

Offline CVX Fever

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Re: Not Easy to Choose Spark Plugs for Outboards These Days
« Reply #13 on: November 08, 2017, 01:28:31 PM »
Quote
I'm thinking Merc knowns more about this motor then anyone would, and if they say "NGK BUHW" that what I'm going to use ...

Gregg that's the route I tend to take. Just go with what the OEM recommends then you know you got the "right stuff" in your engine. Even if someone tells me " but this is better and costs less", I still run the OEM stuff. 

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Offline V153

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Re: Not Easy to Choose Spark Plugs for Outboards These Days
« Reply #14 on: November 08, 2017, 08:11:58 PM »
Well that and ya won't void the warranty ...
'81 Baja 15SS_140 Frankenrude_66.7 mph
'70 something SpeedCraft_(Allison 16R Clone)_Restoration In Progress


WALK TALL AND CARRY A BIG BILGE PUMP

Offline Diamond Chad

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Re: Not Easy to Choose Spark Plugs for Outboards These Days
« Reply #15 on: November 08, 2017, 08:46:11 PM »
What's that?  started with "w".  War_rent_tee.  Don't seem to have one of those, keep losing the darn things.
87 CVX18 5.7
88 CVX16 115 Merc
57 Dunphy Imperial Musky - 57 Golden Javelin
01 Malibu Sunsetter 21 LSV 340 EFI

Offline Plugcheck

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Re: Not Easy to Choose Spark Plugs for Outboards These Days
« Reply #16 on: November 08, 2017, 11:08:05 PM »
Just some fuel for the discussion, and your welcome to research on your own but in a nutshell, here is my $0.02 on  plugs.  Surface gap plugs vrs point gap plugs will fire at a lower voltage.  Fouling is also less prevalent given the area the spark can jump.  Generally, the surface gap plugs are colder than point gap.  The effect of allowing a lower arc voltage prevents the coils output energy from seeking an alternate path.  Coil insulation and plug wires will break down over time.  So there is some validity to the argument of preventing other ignition faults by using OEM recommended plugs. 
Michael
1979 CVZ-18 388 CI Vortec Mouse
1980 CVX-16SS 140 Mercruiser
1979 CVX-16 Johnson 175
2002 Bennington 2275CC 90 Mercury
1985 Intimidator project, gps 85 mph (on trailer)
1989 Lowe 200 Redneck fishin Toon

Offline Hot Rod Roy

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Re: Not Easy to Choose Spark Plugs for Outboards These Days
« Reply #17 on: November 09, 2017, 01:16:55 AM »
Surface gap plugs vs. point gap plugs will fire at a lower voltage.  Fouling is also less prevalent given the area the spark can jump.  Generally, the surface gap plugs are colder than point gap.  The effect of allowing a lower arc voltage prevents the coils output energy from seeking an alternate path.  Coil insulation and plug wires will break down over time.  So there is some validity to the argument of preventing other ignition faults by using OEM recommended plugs.

Why aren't surface gap plugs used in 4 stroke engines?   You must be the man!   You have the right name for this discussion.   Where'd that come from?

 8)
1950 Chris Craft/Mercury
1974 CV-16/Evinrude 115

Offline Hyperacme

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Re: Not Easy to Choose Spark Plugs for Outboards These Days
« Reply #18 on: November 09, 2017, 07:45:48 AM »
" Why aren't surface gap plugs used in 4 stroke engines? "

I read that standard plugs get the spark deeper into the combustion chamber.

Also read where J/E fuel injected (Ficht & ETEC) models need there plugs "Indexed" ...  so the electrode of the spark plug is away from the fuel injector nozzle.

Gregg
'76 CV16

Offline Plugcheck

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Re: Not Easy to Choose Spark Plugs for Outboards These Days
« Reply #19 on: November 09, 2017, 08:31:17 AM »

Why aren't surface gap plugs used in 4 stroke engines?   You must be the man!   You have the right name for this discussion.   Where'd that come from?

Surface gap plugs are used in some competition engines, such as F-1, mainly due to combustion chamber design.  There just isn't room for the ground electrode in those engines.  As for clocking the electrodes, or making sure the gap points towards the cylinder has long been a trick of racers.  We set  when the heads are off, and sometimes just by marking the plug with a sharpie and checking before we put the coilpak or wire back on.     As for my moniker, in my early days of boating, really not too long ago, I would spend a lot of time checking stuff and getting ready for getting on the water, but in my haste and excitement, I would forget to put the bilge plug in.  So similiar to the old biplanes, they would yell "Contact" to tell the pilot to energize the ignition, my friend Tim and I would yell "Plugcheck" before heading to the truck to back in.  So it kinda seemed fitting, since I've done this several times now. 
[/quote]
Michael
1979 CVZ-18 388 CI Vortec Mouse
1980 CVX-16SS 140 Mercruiser
1979 CVX-16 Johnson 175
2002 Bennington 2275CC 90 Mercury
1985 Intimidator project, gps 85 mph (on trailer)
1989 Lowe 200 Redneck fishin Toon