1986 Johnson 150 HP, Model J150TXCDC Spark Plugs

[Terrapin]

My OMC Service Manual recommends Champion Spark Plug QUL77V with the alternate being UL77V. What is the correct plug for this engine? I have been running the Champion UL77V surface gap plugs over the years. My use varies between trolling and running around at 3,000 to 3500 RPMs, not at high speeds of 5500 RPM. I have no running complaints, and only experience an occasional engine die at low trolling speeds. I see forum reference to a QL77JC4 Champion Plug which is a gapped plug. Given my usage, what plug should I be using? If I should run the gapped plugs what should I set the gap to?

Secondly, I have never changed out the spark plug wires since I purchased this boat/motor in 2003. I usually have other maintenance items to consume me. Should I replace the spark plug wires as a preventive maintenance item? If so, is there a source for made up wires of the correct length? The service manual implies making your own up from OMC components.

Thanks,

 

[Faztbullet]

That model uses only UL77V or QL16V which is the better plug

 

[Terrapin]

So with that said, the QL77JC4 Champion is not a gapped plug option for this model number? I'm just trying to confirm as I've seen it referenced as an option with various older Johnson outboards digging around this forum. I thought maybe the QL77JC4 may have been some sort of later modification or technical service bulletin add to the engine service information.

I have never seen the QL16V listed for this engine. Can I ask what makes it a better option than the QUL77V or UL77V ?

Any help with my question regarding the spark plug wires would be appreciated.

Many thanks !

 

[Terrapin]

Doing some further research using the Johnson model number and the marineengine parts site, I see they have the Champion QL77JC4 listed as the correct spark plug to replace the original OEM number 0502180. There is no mention of the Champion UL77V I am currently running in the engine. Any help with the above questions would be appreciated.

Thanks,