SPARK PLUG QUESTION?

jasper astro · May 12, 2005

My 1990 50 hp calls for ngk2522 type plugs. These are considered marine plugs from what I am told by our mechanic here at work. Also he says that marine plugs dont do as good a job as regular plugs do. Dony know what kind of line this guy is feeding me, but I need some input on this before I go out and buy a new set of plugs tonight. Which do you recommend? and why... Maybe I am on the wrong topic page, but this is were I find the most help for my Force motor, Thanks ..... jas...petey

JB · May 12, 2005

Re: SPARK PLUG QUESTION?

Hi, Petey. Some guys just have to think up something to say that they think makes them seem knowledgable. There is nothing, NOthing correct in what he says. Use the plugs the manufacturer recommends.

jasper astro · May 12, 2005

Re: SPARK PLUG QUESTION?

I figured as much, this guy is a complete village idiot who knows everything. But I have to prove him wrong on this. He swears up and down that marine plugs are no good. I think to differ. jas....petey

Silvertip · May 12, 2005

Re: SPARK PLUG QUESTION?

Ask him to explain "why" in detail.

BrettNC · May 12, 2005

Re: SPARK PLUG QUESTION?

Unless he engineers spark plugs all day then I would ignore everything he said about them.

eurolarva · May 12, 2005

Re: SPARK PLUG QUESTION?

Mercury site calls out UL-18V plugs for that motor. Post your model number. There are about 15 model numbers for that year. If merc sells them for 3.70 a piece NAPA probably sells them for 2 bucks each. Some marine plugs have resistors built in to reduce RF noise that could effect onboard equipment such as depth finders. The NGK plug you mentioned probably cross reference to the UL-18V

peteypug · May 12, 2005

Re: SPARK PLUG QUESTION?

I looked up the plugs for the 50 hp 1990 model, and the plugs are good for 1989-1991 models with prestolite ignition. Ngk2522,ngkbuhx. This was on ebasic power marine parts website. The plugs i just pulled out were champion L76V, and they did not look to good. Not burned up, but a slight build up of goo on the ends. Model number of engine, 22530. That is the only thing I can read on the i.d tag, its unreadable. But thats whats on my paperwork. Ebasic website is pretty acurate and it gave me that plug number for that year, all models. jas....petey

eurolarva · May 13, 2005

Re: SPARK PLUG QUESTION?

Item 21 Force 50HP Power Head You want the tips to be slightly gooey. Dry tips mean you are running lean. Slightly rich is better.

peteypug · May 13, 2005

Re: SPARK PLUG QUESTION?

Strange the way these marine plugs are, iam so used to gaping a plug. My son was baffled by the looks of these plugs. Hope i have the right plug, wish there was a way to find out cross reference info. The plugs I took out were marine plugs,but the numbers dont sound correct. Going out to hook up boat....be back in a few minutes.....jas...petey

artw45 · May 15, 2005

Re: SPARK PLUG QUESTION?

A lot of times the only difference in the marine and auto plugs is that the marine plug may be stainless steel. At least that's the case with my 35hp Johnson. As for brand and type preference, I know people who hate the same brand other people swear by. So go figure. Art

rayiow · May 15, 2005

Re: SPARK PLUG QUESTION?

i have a 1989 50hp us marine force(507F9B) and when i took my plugs out i thought that they had been flattened and thought the engine was shot!!!as i had never seen plugs like these before,but all was fine i just need to try and get some new ones as spares now.what is the idea of this design? is it to get higher compression??

jasper astro · May 16, 2005

Re: SPARK PLUG QUESTION?

NGK 2522 BUHX. 1989-1991 FOR 50HP. Just put a new set in my motor. 2.69$ a piece at boat shop, 3.29$ at napa. As far as the idea of design, something to do with difference of marine and auto ignition applications. jas..."petey"

SBellew · Aug 16, 2009

Re: SPARK PLUG QUESTION?

Can anyone tell me which spark plug to use in my 1972 Chrysler 35hp (model# 357HD)? The engine came with Autolite 425 in it when I got the boat and I do not have my manual yet.

Also, it runs good, but does not sound like it is opened up and WOT and runs 7.5 MPH (GPS) on a 16 foot 1976 Chrysler Pro Bass Runner. I would think that it would run a bit faster, but this is my first boat other than an old flat bottom I used to have.

roscoe · Aug 16, 2009

Re: SPARK PLUG QUESTION?

my chart says autolite 4092

or champion 5933

or ngk br6hs

yes, boat should be faster,

is it firing on both cylinders?

SBellew · Aug 18, 2009

Re: SPARK PLUG QUESTION?

roscoe said:
my chart says autolite 4092

or champion 5933

or ngk br6hs

yes, boat should be faster,

is it firing on both cylinders?

Thank you, I pulled each wire last night and both cylinders are firing while running. When I pulled each, I could tell that the engine dropped RPM's. Sounds like it revs higher when out of gear than it does at WOT while running in gear in the water. I cleaned the carb yesterday before putting it in the water. I get a smooth idle, but it just does not seem to run at true WOT in the water to me.

Anyone near Gadsden, AL that would help a outboard newbie tackle their first outboard?

moparman · Aug 19, 2009

Re: SPARK PLUG QUESTION?

sbellew,I'm in the b,ham area, if I can help you ,pm me and I'll do what I can .MOPARMAN

Frank Acampora · Aug 19, 2009

Re: SPARK PLUG QUESTION?

Well, Jasper: Marine plugs or surface gapped plugs are dead cold. Because of that, they tend to oil foul rather quickly. In that respect, they don't do as good a job as regular plugs. HOWEVER: They also don't melt pistons. The factory engineers set plug type for a reason; don't try to second guess them.

Jeremy90bay · Aug 19, 2009

Re: SPARK PLUG QUESTION?

I dont know if this helps but I wanted to put in my 2cents. I ad bent electrode plugs in my motor when I got it. I asked on here what were the correct plugs and I was told UL18V checked it out and that was right. I replaced my origanal plugs with the correct ones and it made a huge differance in the running of the boat. I did nothing else to the motor, at this time, except change the plugs. so im a firm believer that the RIGHT plug is chosen for a reason. Thanks frank.

SwampThing · Aug 19, 2009

Re: SPARK PLUG QUESTION?

Frank Acampora said:
The factory engineers set plug type for a reason; don't try to second guess them.

I so so so #@$#! co-sign this!

I come from a huge family of automotive engineers. All components are designed the way they are for a reason. Contrary to popular opinion, most components ARE NOT engineered with a minimalist mindset or approach.

In fact it's the exact opposite. Components are designed to the best standards possible under all foreseeable conditions. Then some one else comes along and tries to design a better mouse trap.

If you can take it off, throw it away, or replace it with a modified part the engineers would have already beat you to it. With ignition components, 9 times out of 10 you're probably just compensating for an ign / fuel issue you have elsewhere. The other 1 time you bought into marketing or "advice" from the self appointed know it all.

I was told the same thing about the BUHX surface gap plugs from a boat mechanic with "20 years experience". "Those plugs are FN junk" was his exact words. Then he wanted to sell me $26 a quart final drive fluid in the same sentence.

Enough said. Dismissed.

Frank Acampora · Aug 19, 2009

Re: SPARK PLUG QUESTION?

YEP! And experience doesn't count for S**T if you have made the same misteaks (sic) for 20 years!

SPARK PLUG QUESTION?

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