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Spark plugs

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Lachrosha kirk

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My 1977 850 Mercury Thunderbolt outboard needs spark plugs. I think I've been running the wrong plugs I have discovered because I have maintienced my motor and and my plugs have lasted two years or longer. Obviously I need new ones ... My manual that I found online says use NKG and they are traditional JAY PLUG. I know I have SURFACE GAP Plugs. How did wrong plug get put in or is the wrong plug.... Look on Google and says Jay plugs are for not a high quality idle or a lot of electronics but if they're not cross references then it can damage. Wth and I've had idle problems but thought it was from when it was messed with when it wasn't the problem and been a hair off since. WHAT'S THE RIGHT PLUG? What do y'all think about surface plugs V/S traditional JAY plugs.
 
Champion L76V, I don't think you can put side electrode plugs in that motor due to clearance issues. Surface plugs (Perma Gap) run cooler.
 
Quicksilver said:
Champion L76V, I don't think you can put side electrode plugs in that motor due to clearance issues. Surface plugs (Perma Gap) run cooler.
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Ok thank you that's what the guy at Napa said. I was confused because the online manual was wrong. Two years I thought was good for spark plugs. I hope this fixes my problem with loss of power. sounds like trash in gas.. Won't plane. I cleaned them at the ramp and it ran great for couple hours then it was back. I'm getting new plugs today and I'll instal. Hope to be fishing Guntersville Sunday. Ill post a update. Thanks again
 
Thank you! I see you used to boat drag. If so can you tell me why someone would tell me my engine was junk and offer a trade. After that I checked PSI which 3 were at 125 and one was 120. That's good right ? I have the Mercury Thunderbolt 1977 and she starts ever time for me.
 
Thank you! I see you used to boat drag. If so can you tell me why someone would tell me my engine was junk and offer a trade. After that I checked PSI which 3 were at 125 and one was 120. That's good right ? I have the Mercury Thunderbolt 1977 and she starts ever time for me
 
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