mercruiser 3.0 lx spark plugs

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regal1999

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Ok i have 1996 regal with a 3.0lx engine we seem to have some issue on what is the correct spark plug it currently has champion rv12yc which is a short reach plug we looked in the owners manual and got another number cross referenced it and got some ac delco spark plugs but they are longer reach plugs i dont want to install them just yet since short reach plugs are in it now and the book is saying long reach plugs it also has a est igntion if that matters any typ of help would be much appriciated... rather find the right plug than have a damaged piston...:)
 

fat fanny

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Re: mercruiser 3.0 lx spark plugs

I run the A/C mr43lts OEM specified never had any luck with anything else and they are long reach.
 

regal1999

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Re: mercruiser 3.0 lx spark plugs

so fat fanny does your boat have the est ignition on it when you run the A/C mr43lts
cause i heard that if its a est or digital ignition and not a plain points ignition the reach of the spark plug will matter so now i am wondering if you have the est ignition ?
 

Don S

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Re: mercruiser 3.0 lx spark plugs

cause i heard that if its a est or digital ignition and not a plain points ignition the reach of the spark plug will matter

Type of distributor has nothing to do with which spark plug you use. It all depends on what the head was designed for. The 3.0LX uses the longer reach plugs, so you would use the AC MR43LTS plugs. you can also use the NGK BPR6EFS.
I wouldn't use champion plugs on any marine engine. To high of a failure rate for me.

One other note for future parts, get your engines Merc serial number and go by it, not by year. The year is of your boat and not necessarily the year of your engine. Then, with the correct part number for your serial number you can then go looking for aftermarket parts if you want them. Just make sure the aftemarket part replaces your OEM part number.
 

regal1999

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Re: mercruiser 3.0 lx spark plugs

thanks don and fat fanny cause i have been really confused since the previous owners had champion rv12yc spak plugs in it which are a shorter now i suppose i am going to have to remove carbon build up from the lower threads also the gap is .035 correct?
 

Don S

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Re: mercruiser 3.0 lx spark plugs

Have you looked at the sticker on either the valve cover or the flame arrestor? There should be one with the serial number of your engine and it also includes tuneup info, like spark plug type, gap, timing, rpm etc.
Here is a link to download the OEM service manual for your engine, free. It has all this information too.

http://www.4shared.com/document/B3wzU5Iz/Service_Manual_13.html
 

regal1999

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Re: mercruiser 3.0 lx spark plugs

yes i got the serial number off the top plate it says .035 but once again i was looking around and i found the gap had changed from .035 to a .045 but i think i figured it out the gap change was for the regular 3.0 l not the lx. thanks don you have been a big help its obvious the prvious boat boat owner who was was suppose to be a marine mechanic did not know what he was doing i want to keep proper maintence and parts on my engine cause proper maintence is key to a pro long and happy marine engine once again thanks DON S AND FAT FANNY ....
 

Don S

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Re: mercruiser 3.0 lx spark plugs

i was looking around and i found the gap had changed from .035 to a .045 but i think i figured it out the gap change was for the regular 3.0 l not the lx.

The 3.0 or the LX version have never been .045, always .035.
I might want to stop listening to everything you read or hear, there is a LOT of just plain wrong information on the internet. Especially on boats.
 

fat fanny

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Re: mercruiser 3.0 lx spark plugs

Just to add to what Don said the year of the boat does not dictate the year of the engine my Ray is a 96 and the engine is a 95 if I remember corresctly it is casted on the engine near the serial #. If you keep it to factory spec's she will serve you well along with staying on board here and educating yourself sticking with the service manual which was free (thanx again Don)
 

groovy_moon

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I know this thread is REALLY OLD but isn't the spark specified on a sticker on top of the air cleaner. I have a 1997 Sea Ray 175 with 3.0 and the it shows AC-MR42LTS with a 0.035" Gap
 
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