76 mercury inline plugs

[fishdog4449]

Hey guys
I'm looking for cooler-running plugs for the Merc..I think I ran champion 76's last year per the owners manual. Does anyone have suggestions as far as brand (ngk/champion or other) or type?
Thanks
MJK

 

[Yepblaze]

Re: 76 mercury inline plugs

I think it called for L74V's which may be a bit colder. (?)

Surface gap plugs are available from AC Autolite NGK Champion, and probably others.

I do not think you are going to find much heat range involved in surface gap plugs period.

Is there some issue you are trying to address?


personally I've never removed a surface gap plug that had anything built up on it hotter or drier that a carbonized goo around the edge. So I don't see much of any way to apply heat range to the equation.

 

[fishdog4449]

Re: 76 mercury inline plugs

Thanks ill try the 74s.
No issues persay, but she runs hotter than I would like. There's nothing wrong, it's propped @ 5600 spinning a 17P aluminum when I'm towing, 19P for cruising (on the boat in my sig), new water pump every year water pressure is great, and linked/synched properly. The fact that the lake where I boat averages 85 degrees in the summer doesn't help either.

 

[Laddies]

Re: 76 mercury inline plugs

The L76V are as cold as it gets you are either running to mach spark advance or the w/pump or system is obstructed, probably the spark advance is the problem.

 

[fishdog4449]

Re: 76 mercury inline plugs

I going to re-tune the engine prior to this season, but I had it set @ 19 degrees max timing. I also ran midgrade fuel an premium quicksilver 2 cycle oil. When I had this problem last year I cleaned the whole cooling system and block and it's perfectly clear.

 

[Chris1956]

Re: 76 mercury inline plugs

Fishdog, If you leave the motor down in salt water, barnacles will get into the space behind the water intakes and restrict water flow. Also, after many years in salt water, the salt can crush the water tube in the top of the midsection and restrict water flow. Both would show on a water gauge.

Other than that, if the impeller is good, the the WOT RPM is good, they run dead cold at idle and warmer at cruise.

 

[Laddies]

Re: 76 mercury inline plugs

There were some 115s back years ago and I can't remember if 76 was the year or not that had the timing decals improperly placed. I would use something down the bore to justify that timing mark on the flywheel and the placement of the decal.

 

[Chris1956]

Re: 76 mercury inline plugs

The 1976 motor should have the plastic timing pointer, and the timing decal should have a punched hole that matches the punch mark on the outer flywheel. As Laddies said, you should make sure the timing pointer lines up with the TDC mark, when the top (no 1) cylinder is at TDC.

 

[fishdog4449]

Re: 76 mercury inline plugs

Thanks for all the help guys! I'll check on that timing.
Chris, it's been run in freshwater only.