Spark Plug Gap

[sumodumy]

Anyone know what the correct spark plug gap is for the AC Delco 41-993 that fits a 2008 mercruiser sterndrive 5.0L? What manual might this info be in since spark plugs are not even mentioned in the operating/maintenance manual that came with the boat? Lastly is there any other plug (NGK, etc) that fits this application?

 

[Don S]

Re: Spark Plug Gap

Look on the decal on the flame arrestor cover. The gap should be .060. BUT!!!!
DO NOT try to adjust them. They are platnum plugs and you could damage them trying to adjust.

 

[sumodumy]

Re: Spark Plug Gap

You're right, it is on the flame arrestor. but now I'm a little confused. It says the plug is AC Delco MR43LTS and the gap is .045 not .060? The original plug in the boat is the 41-993 - are these one in the same?

 

[Don S]

Re: Spark Plug Gap

Sorry, but I can't tell you for sure, never seen a 2008 engine and have no way of getting any 2008 info. They may have a service bulletin out about the decal being wrong (it's happened before) or you have an older engine. SN's is what works for Mercruiser, not years.

 

[sumodumy]

Re: Spark Plug Gap

Thanks Don, I believe the difference between the plugs is one is platinum and the other is not. That plus the 41-993's (platinums) are significantly more expensive than the MR43LTS. The boat was purchased in California, so I don't know if the platinums were put in for the Cali emissons requirements or if that even makes a difference. If (plugs) are replaced annually (due to getting coated from fogging), I don't know why you would want to spend the extra for platinum - just go with the MR43LTS plugs in my opinion. BTW what does SN's stand for?

 

[Don S]

Re: Spark Plug Gap

BTW what does SN's stand for?

Serial Number