496 changing sparkplugs ?
 

35 fountain twin 496's the rear two center plugs how do you people get to them?

Why are you changing plugs. these are platunum tipped plugs and if they are running ok they should just about outlast the engine and the boat?

Best Regards,
Ray @ Raylar

Thay are diffacult to get but can be done. I have seen several engines with those plugs that fail between 200 and 300 hours. The #7 plug is the hardest.

hi Ray
thank you, you stand correct I thought I had a bad plug and found out is was a wire.I changed one plug and said I have to change all what a mistake that was.I had to pull the fresh water tank on the port side and the holding tank on the starboard side.I just have a problem with the rear two in the center do to the fact I am a little portlie lol on me.So who was the brain child that said size matters not in this case.
regards Paul

A tech deep at Merc suggested they should be changed every year...

They are also in the business of selling parts, what do you think they are going to say?

I'm with Ray, why change them if there is no reason to think they are not working. How many times do they actually fire over the lifetime of a marine motor? Think of how often your car's plugs fire and you probably don't touch those for the life of the car!

I thought merc recommended changing them at like 300hrs.

I think in our area it may have something to do with the saltwater use. My shop has had three boats in six months with some bad plugs.

then there is something else wrong. modern plugs with modern ignition , in nominal circumstance should last exactly as ray says.

The only real valid reason for changing platinum plugs is that even the best quality stainless plugs will eventually corrode and then it is a real pain to get them out. For boats that sit in the saltwater or in any salt environment I recommend changing them every couple years regardless of hours. If you have to pay some one to extract one plug that snaps at the base it will cost alot more then a set of plugs.

You are correct Griff...it is either 250 or 300 hours. I have noticed one other tid bit, Merc has changed the type of plug being used. I'm going to pull out a new AC 41-983 and compare the heat range to the original Denso plug.

A direct replacement would be AC41-983. But please let me know if I'm wrong.....

That is the number that merc gives in the parts catalog and thats what we use in all of them.

and plugs werent designed to last for ever.....

I would think a max interval of 5 years/ 500 hours. I did mine and found them pretty rusty. Leave it much longer and they won't come out properly. They showed some wear on the electrode also. Plus it gives you a look at whats going on.

I couldn't find a service interval in the service manual.

I was able to find the ac delco 41-983 plug at Oreilys - $5.88, GM dealership was $12.15. Scared to check with Mercruiser.

THe ones I pulled out were gapped at 1/16", seemed to be a huge gap. So wide I could check it with a caliper!

What is the correct plug gap for these in a 496??

Good price...I bought mine from Summit Racing @ $5.95/each

i got mine from napa 6.25 ea

What is the correct gap?

and .....who know's what the gap should be???????????

.60

yep, believe it's on your cowl sticker as well

.060 not .60, big difference:drink:

And that us only .0025 shy of 1/16 so that measurement was right on the money

Yeah using the wife's keyboard and hit a dot instead of a zero. Anyone that would have interpreted the answer as "six hundred thousanths" is...... well....

But, yes I stand corrected and the correction will help your post count. Otherwise why on earth would you bother with that?

I changed out my factory 'platinum' plugs at 250hrs. Boat idled smoother and seemed more responsive afterwards. 496mag. Old plugs showed electrode wear resulting in gap way off.

Auto engines don't run at 3 and 4k all day either. ;)

mb.

You know, I used to post on this forum a lot a few years back, mostly here in the tech section. Because of d!ck bags like you I stopped. I have helped out a lot of people on here over the years, there are a wide variety of boaters on this site and some do not understand the difference in those two measurements, believe me. You would never manage to get a plug gapped to .600 but some poor fellow may try and ruin a fairly expensive plug doing it. I do this for a living day in and day out and have seen a lot of silly sh!t over the years.

And by the way, I could give a sh!t less about my post count, I didn't even pay for a membership this year. I don't spend near as much tie hanging around this place as I used to and I realize why more and more every day.

You are correct, the zero and the six where superimposed....doh

Hillbilly....let me buy you a beer....dont quit on the rest of us dummies ok!!

mike

Thanks for the info.

That's a good thing I suppose. If you spend more time banging on someone for typo's rather than using the info that they try and help provide it could prove to be frustrating. But you're still here. Bottom line is it doesn't take much to figure out that dot since it's not possible to do what you're suggesting and only the best intention was there to help the guy. I meant nothing else by it and did not intend on damaging a $9 spark plug. Heck, I'll send him a set if you want me to. I really do like to help people on here as they've help me.

You have a couple of run-on sentences above separated by commas instead of periods (.). Those are dots too...

Take care hillbilly,
Your new favorite d!ck bag
:ernaehrung004:

Round of hugs for everybody!!!!

No kidding huh? :circle:

You seem to think my post was some kind of personal insult to you, it was not nor was it intended to be. It was a clarification. I spoke nothing of your intentions and certainly did not think you were trying to get a guy to screw something up. The last thing I expected was to be basically called out as a pretentious a$$ hole for correcting a typo and yes, I know that's all it was, a typo.

I have had problems with run on sentences since third grade, I guess I will never grow out of that one.

If you happen not to get anywhere on your own, you could try Paulie Brown's Marine on Hwy 79 if he's still open. He was a good Merc guy when I was growing up there. It's a bit of a drive from Owensboro but I know he's an ethical person to deal with. Good luck!

I guess from my point of view it seemed unnecessary to pick it apart but I'd also have to agree that it would be ugly if someone actually took it literally. This mistake was on me.

Then the "d!ck bag" part came in and took a tooth off of my gear.

Either way, no hard feelings. This should be a place where guys work together; not against one another.

Cheers!
:cool:

I am a little quick with the insults a lot of times, sorry to be such a douche bag myself. I know you are not part of the issue but there has been some just plain bad tech advice around here lately and people who don't know a thing about what they are talking about seem to feel the need more then ever to jump in and give what they consider definitive answers. I am not a master of everything either but I just keep my mouth shut when I don't know the answer. Again I am not insinuating in any way that you are part of this issue, it just has me pissed off with this place lately.