Spark Plug Question

FinallyABoat

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May 8, 2008
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5
We just purchased our first boat, and it has a 1989 Johnson J40ELC outboard. At my father's advice, I was told to change the plugs, so I went by the local dealer and purchased new ones. I was given L77 JC4, but when I removed the old ones, they were QL 78YC. Which ones should I be using?

Thanks
 

FinallyABoat

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May 8, 2008
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Re: Spark Plug Question

Thank you Seahorse 5. However, it shows a completely different plug. Which one of the two I listed should I use? Is there any difference?
 

rickdb1boat

Supreme Mariner
Joined
Jan 23, 2002
Messages
11,195
Re: Spark Plug Question

The correct plug for your engine is the QL78YC..
 

FinallyABoat

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May 8, 2008
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Re: Spark Plug Question

Is there a reason why the boat shop would say to use the other plug?

While I have the experts online, what brand/type of oil would you recommend for me to use when mixing the fuel. What is the best ratio?
 

seahorse5

Rear Admiral
Joined
Jan 24, 2002
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4,698
Re: Spark Plug Question

Thank you Seahorse 5. However, it shows a completely different plug. Which one of the two I listed should I use? Is there any difference?

Did you read the chart wrong? It says QL78YC as long as you are sure it is an '89 40hp.
 

FinallyABoat

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Re: Spark Plug Question

Absolutely read the wrong 40 hp. Any suggestions/knowledge to share on the oil?
 

tashasdaddy

Honorary Moderator Emeritus
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Nov 11, 2005
Messages
51,019
Re: Spark Plug Question

oil is oil, as long as it is certified to be TC W3, outboard motor oil. it is fine. a lot of us use, walmarts Super Tech products, and Pennzoil products. high price does not mean it is better oil.
 

FinallyABoat

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May 8, 2008
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Re: Spark Plug Question

I just wanted to say thank you for all of the help with the plugs. I picked them up Friday afternoon and the engine started on the first few turns of the starter. I let it idle for about 5 minutes and it ran well. Now, we can't wait to go fishing next weekend...the weather prevented it this last weekend.

Any suggestions on a battery for the trolling motor and live well?
 
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