Minnesota Classic Glastron Forum

General Category => General Discussion => Topic started by: David CVX-16 on November 05, 2017, 03:00:36 PM

Title: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: David CVX-16 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 (http://www.sparkplug-crossreference.com/convert/CHAMP_PN/QL77JC4)
Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: Hyperacme 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 ...
Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: David CVX-16 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.
Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: Plugcheck 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. 
Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: V153 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?
Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: David CVX-16 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.
Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: Diamond Chad 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.
Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: Hyperacme on November 07, 2017, 12:33:32 PM
NGK.com / Spark Plug Terms
https://www.ngk.com/glossary/8/spark-plug/S (https://www.ngk.com/glossary/8/spark-plug/S)


Surface gap ...

(https://i.ebayimg.com/images/g/re4AAOSwBahVFj1C/s-l500.jpg)

(https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQD8erXnNmCB2dE9WKB0WkhdHdUS1A8f5M_3JUCkRRLy5LPXpvH)

Standard spark plug ...

(https://images-na.ssl-images-amazon.com/images/I/51sXDI2oqkL.jpg)
Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: David CVX-16 on November 07, 2017, 01:06:34 PM
Why one should change spark plugs often: easier on the power pack. Spark plugs are cheaper than power packs.

http://www.marineengine.com/boat-forum/showthread.php?396023-Surface-Gap-Plugs-are-they-good-or-better-or-necessary-if-that-s-what-your-motor-calls-for (http://www.marineengine.com/boat-forum/showthread.php?396023-Surface-Gap-Plugs-are-they-good-or-better-or-necessary-if-that-s-what-your-motor-calls-for)

Types of spark plugs:

http://www.autolite.com/media/11850/sparkplugtypes_0.pdf (http://www.autolite.com/media/11850/sparkplugtypes_0.pdf)
Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: Diamond Chad 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.
Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: Rich_V174SS on November 07, 2017, 04:32:12 PM
Nothing to set on a surface gap plug, they are what they are.
Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: Hot Rod Roy 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)
Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: Hyperacme 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 ...
Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: CVX Fever 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. 

Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: V153 on November 08, 2017, 08:11:58 PM
Well that and ya won't void the warranty ...
Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: Diamond Chad 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.
Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: Plugcheck 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. 
Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: Hot Rod Roy 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)
Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: Hyperacme 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.

Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: Plugcheck 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. 
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Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: David CVX-16 on November 09, 2017, 05:46:57 PM
Look at the condition of the plug when you take it out.  Plugs running too hot and there can be pre ignition or detonation. Plugs running too cold and the engine will miss/foul and the idle will be poor. 
Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: V153 on November 09, 2017, 06:36:47 PM
Bingo Mike. Surface gaps are used when there's no room left to have an electrode pokin into the combustion chamber. And or no way to index a conventional plug.
Title: Re: Not Easy to Choose Spark Plugs for Outboards These Days
Post by: Hot Rod Roy on November 15, 2017, 07:46:42 PM
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.

Oh!   That kind of "Plug Check"!

 8)