I hear you can tell a lot by looking at spark plugs. How do my plugs look?

Port side plugs from left to right 1,3,5.


Starboard side from left to right 2,4,6


Too me 1 and 6 look like there is extra carbon built up. Not sure what that might mean.

They all have carbon around the center electrode. The plugs should actually look a little wet. Low grade or too much oil, premium fuel, running a lot of low RPMs and too much pitch on prop will cause this build up. Are you pre-mixing? A good additive like Sea Foam will help.

I use Pennzoil Premium Plus Marine for my oil. I have one of the fancy measuring containers and premix my gas and oil. I use regular non ethanol gas for my motor and I have Seafoam in this current tank. Would you recommend a different brand of oil or maybe decarbing the motor?

The plugs were all wet when I pulled them but by the time I found the phone for a picture the fuel pretty much evaporated that's why they look dried out.

I would use a true decarbonizing fluid to clean the motor then replace plugs. Mercury Power Tune. Yamaha Combustion Cleaner, BRP Engine Tuner. Follow the instructions.

Are those the right plugs for that motor? I thought the OMCs of that generation ran best on 77JC4s not perma gaps.

thats what i was thinking..I know for sure my 175 would not run on anything but those Champion...

These plugs are OMC. There was an update that if you do a lot of low speed idling then switch to JC4. I don't idle very much so I use the original OMC recommendation. If I am wrong then please let me know.

I'm in the dark here, but I believe some OMC have changed to NGK, which are not Champion..is that a cross over plug to a Champion or a Champion plug...I didn't like the price of the Champion so I tried others but had to go back to Champion..maybe just me and my motor.....

Like I said I'm no expert, but I know I tried several different plugs and all ran like poop, except Champion...

Not sure what is spec'd for the OMCs. My mechanic's brother told me once to run some L77JC4s in my Merc.. He said that is what they run in the blue and the white motors. I tried one set and went back to 78Vs. The 78s are a little hotter plug versus the 76s. My motor has milled heads and seems to run better with the 78s versus the 76s. I have tried a set of NGKs too. They did nothing for me.