Reading spark plugs and ignition timing (5 Viewers)

[MooseMarine]

I just finished the first tune up on my 40. It's a 78 with a 75 dizzy. When I pulled the plugs I noticed a ton of white buildup on them. The chart in my Haynes manual indicated it was from fuel or oil additives. I've run seafoam in the fuel before, and add the rislone ZDDP additive to the oil. The points were pretty burned up as well. Anyway, I set the timing on the BB and it runs much, much better now. Thoughts?

 

[Pin_Head]

They look pretty normal to me except that they may have a lot of miles on them.

 

[MooseMarine]

Thanks for the reply. The buildup was pretty uniform across all six plugs. It's been at least two and a half years ~ 12,000 miles since I bought it, and was curious about their condition.

 

[Pearly]

 

[Tentsontop]

I just recently replaced my plugs (Nippon Denso) that had about 20K on them and they looked just like yours. I have the NGK coppers in there now. I was running Mobile one that was a bit on the thin side. Figured that might have been one reason for the ash.

 

[Weber Sarge]

Ash deposits are usually from oil , I've also had issues with our junk modern fuel causing this as well .
Sarge

 

[PabloCruise]

Do you guys like 25k replacement interval for plugs?

 

[Weber Sarge]

I'd run NGK copper , 15-20k should be about right depending upon driving habits .
Sarge

 

[MooseMarine]

I just switched from Rotella to Castrol 20w/50. I'll pull the plugs in 1k miles and see if they are starting to ash up again.