MERCRUISER 3.0 SPARK PLUG GAP

[RSHOOTER]

This is a new engine 135HP, 4Cyl, with Carb.
Owners Manual says spark plug gap of .045 or .9mm. Problem is .9mm is the same as a .035 Gap so one is wrong.
The Repair Manuals I have read say .035. Which is it?

 

[Don S]

Re: MERCRUISER 3.0 SPARK PLUG GAP

.035 is what is called for in the OEM manual. Also look at the flame arrestor decal on the cover. It should verify this.

 

[RSHOOTER]

Re: MERCRUISER 3.0 SPARK PLUG GAP

Thanks Don...the Merc Manual that came with the Motor has the noted discrepency that I mentioned. I will check the decal. I did e-mail Merc and they insist it is .045 but I don't think they thought about it before answering.

 

[Don S]

Re: MERCRUISER 3.0 SPARK PLUG GAP

Found a service bulletin for the plugs, the gap is now .045 (1.14mm)
The bulletin number is 2006-3

 

[RSHOOTER]

Re: MERCRUISER 3.0 SPARK PLUG GAP

I wonder why the change? Less fouling?

 

[Wetbehindears]

Re: MERCRUISER 3.0 SPARK PLUG GAP

Hello,
Sorry to jump in the thread, but do you think its the same for the 3.0 LX ? I just happen to be doing a full tune up on a 97 3.0LX and I know the heads are different, so will that make a difference?

 

[Gary H NC]

Re: MERCRUISER 3.0 SPARK PLUG GAP

Don was talking about a 2006 service bulletin.
I would bet the 97 is still .035..

 

[Don S]

Re: MERCRUISER 3.0 SPARK PLUG GAP

I have no idea WHY the change, Merc doesn't tell us why on anything, Just here are the new specs, use them.

Wet, check your serial number. The bulletin is for ALL engines starting with a SN, Merc doesn't go by Year on this kind of thing, only SN.

Here is a copy of the bulletin so you guy can read it. Now you will know as much about it as I do.

Service Bulletin 2006-03

 

[whitmorewoody]

Re: MERCRUISER 3.0 SPARK PLUG GAP

Ok -- I also have a '97 Glastron with the 3.0 -- BUT the engine number is "OK123456"; not an 'SN' number. Should I change the gap to 0.045"? The arrestor cap denotes gap as 0.035", but am wondering if I may perform better or pull more MPH/MPG with a change like this. Any recommendations on the BEST plug to use? Does it really matter? Have been using AC Delco in the past....
Thanks much!

 

[fat fanny]

Re: MERCRUISER 3.0 SPARK PLUG GAP

Don could not open service bulletin (address and or typing error) so says the puter but does it cover 0f553706 ??

 

[Don S]

Re: MERCRUISER 3.0 SPARK PLUG GAP

You guys need to start new threads with your particular engines. The service bulletin doesn't work because it's a 2007 thread, and that ISP doesn't exist any more.