Changed spark plugs, your analysis please

[madurodave]

I run a 5.0, V8. Boat runs great so I had little reason to change the plugs, right? I now understand that that statement is false. As a matter of fact, had I known then what I know now, I may own a different boat.

Anyway, what's done is done. I change the plugs today and this is what I found. First observation is the 2 plugs closest to stern have a trace of oil on the top 2 or 3 threads. This indicated wet fouling occured. The engine was rebuilt last summer but I would be naive to think that is the reason why. The others look okay, other that they care cold fouled. Only 3 of the 8 look acceptable to me. Thanks again for the manual, Don.

Please offer your analysis and tell me what I may be in store for, based on this picture. Thanks in advance.

EDITED TO NOTE: None of the gaps are correct on the old plugs, measuring closer to .035 than .045 (spec).

 

[rbh]

Re: Changed spark plugs, your analysis please

yes sir
tan insulators good, black not so good, still white with aluminum spects lean I believe?
and if thats the first set of plugs since a rebuild, things could still be trying to seat, how many hrs?
rob

 

[FreeBeeTony]

Re: Changed spark plugs, your analysis please

Are the electrodes deformed? They look pointy to me............

 

[madurodave]

Re: Changed spark plugs, your analysis please

yes sir
tan insulators good, black not so good, still white with aluminum spects lean I believe?
and if thats the first set of plugs since a rebuild, things could still be trying to seat, how many hrs?
rob

10 tops?

 

[madurodave]

Re: Changed spark plugs, your analysis please

Are the electrodes deformed? They look pointy to me............

no, they are flat at tips.

Strange all the gaps where .010 shy

 

[Bifflefan]

Re: Changed spark plugs, your analysis please

Are the electrodes deformed? They look pointy to me............

are those platinum or urideum plugs.
are they a little to long of reach? looks like they have some build up on the threads.
They dont look too bad besides the one on the right.
How long have they been in?

 

[madurodave]

Re: Changed spark plugs, your analysis please

are those platinum or urideum plugs.
are they a little to long of reach? looks like they have some build up on the threads.
They dont look too bad besides the one on the right.
How long have they been in?

I am now paranoid, as they are not to spec. PN is ACDelco 41-993. Might explain why the gap not to spec.....

Platinum

10 hours, maybe? not positive as I don't believe a word this clown told me.

 

[bruceb58]

Re: Changed spark plugs, your analysis please

Taking a plug read totally depends on what was happening right before you took them out. If you were idling for any length of time before you stopped your engine, reading these are meaningless pretty much. You need to a high speed run stop the engine and pull the plugs.

Curious why you are using those plugs. You have Vortec heads? What ignition system are you using? Never understood buying platinum plugs for a marine engine.

 

[madurodave]

Re: Changed spark plugs, your analysis please

Taking a plug read totally depends on what was happening right before you took them out. If you were idling for any length of time before you stopped your engine, reading these are meaningless pretty much. You need to a high speed run stop the engine and pull the plugs.

Curious why you are using those plugs. You have Vortec heads? What ignition system are you using? Never understood buying platinum plugs for a marine engine.

yes. good question. I replaced per the manual. We shall see....

 

[madurodave]

Re: Changed spark plugs, your analysis please

On a freshly built engine I don't think they are too bad. I would toss a new set in, run a few hours and then re-inspect.

As you have the plugs out, a quick compression check wouldn't hurt anything. Record your findings for future comparisson.

will do bubba. thanks!

 

[jstutz101]

Re: Changed spark plugs, your analysis please

I run a 5.0, V8. Boat runs great so I had little reason to change the plugs, right? I now understand that that statement is false. As a matter of fact, had I known then what I know now, I may own a different boat.

I would think if it's running good you might just want to try and enjoy it.

"If it aint broke don't fix it!"

 

[madurodave]

Re: Changed spark plugs, your analysis please

I would think if it's running good you might just want to try and enjoy it.

"If it aint broke don't fix it!"

Your right, J! and I think I am hitting the lake tomorrow. Thanks for your thoughts, guys!

 

[abj87]

Re: Changed spark plugs, your analysis please

regap them and throw them back in plugs last hundreds of hours.

 

[user64]

Re: Changed spark plugs, your analysis please

yep..agree with abj...had a similar issue..plugs were gapped to .35 when specs called for .45 and resembled your picture..boat ran fine.. Regapped them and they look great..remember wider gap= fatter spark

 

[bruceb58]

Re: Changed spark plugs, your analysis please

I will repeat my question from before. Do you have Vortec heads?

 

[sickwilly]

Re: Changed spark plugs, your analysis please

Is your v-8 fuel injected or carb? There is a mercruiser technical service bulletin on spark plugs (search for it) that specifies that the platinum plugs can be used in the carb engine if gapped differently. Maybe that is why all yours are gapped differently than spec.


http://74.125.93.132/search?q=cache...iser+spark+plugs+service+bulletin&hl=en&gl=us

 

[madurodave]

Re: Changed spark plugs, your analysis please

I will repeat my question from before. Do you have Vortec heads?

I am embarrased to say that I don't know.....

and thanks willy. carbed. I installed the ones from the manual though. may have to put these back in

 

[madurodave]

Re: Changed spark plugs, your analysis please

I wanted to follow up to this. I put the new plugs in and the motor didn't start as well. I also smelled the exhaust more than before.

Make sure you use the plugs noted on the service bulletin!!

Remember this guys, Don't fix it if it's NOT broke! I now have to get the right plugs installed!

 

[bruceb58]

Re: Changed spark plugs, your analysis please

If you have a Vortec head you use completely different spark plugs than a non Vortec head.

 

[dr_bowtie]

Re: Changed spark plugs, your analysis please

depending on ignition used to depends on the plug you should use...Platinum plugs take more engery to fire than regular plugs...so the coil has to work harder...

also the gap on the plug also has to do with how hard the coil works...less gap means less of a spark and easier on the coil...

wider gap means fatter sparker but harder on the coil and can contribute to a mis-fire...