Spark Plug Gapping on High mileage Engine

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THRobinson

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I read this in passing years ago, and of course now can't find it.

When gapping plugs, there was some sorta rule about adjusting the gaps size every XX number of miles/km. I can't remember if was a bigger gap? smaller gap? or by how much.

Anyone know?

My engine (2003 Ram 1500 - 5.7l Hemi 4x4) is a few weeks from hitting 400,000km which is about 250,000 miles. What gap space would I be looking at? Good chance my plugs are all originals, was looking at kits (NGK) online to replace the wire/plugs/coils.
 

Oliver Closehauf

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I think that was relevant when ignitions used points. Probably should stick with the recommended gap.

Now if you are burning oil you might want to go with a hotter range plug to help keep it from getting fouled, but that's all I'd do.
 

Oliver Closehauf

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A hotter plug will have less insulation on the center electrode which allows it to get and stay hotter. That helps burn off the goo when you have worn valve seals and rings.
 

turkeybird56

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To add a visual to what Oliver explained above.

View attachment 499899
@chopperman1: He not driving an M-60, LOL. but yeah, on extremely high mileage motors, U can go hotter. With 250K miles on the motor, I sure hope those are not original plugs. Gonna need a blow torch to get em out (lol).

OP: U may need to spray alike WD40 thread areas of plugs and when U pull them, go easy and slow, If they original and that many miles, well U know, heated in there, brittle, etc.,. Just go Real Slow and Easy.. All above IMHO .....
 
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THRobinson

THRobinson

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They don't look too bad to do myself, except that one set at the back near the driver side... seen a few vids and looks like gonna need a flex joint and low profile socket for those.
 

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