'93 300-6 auto trans. 90K mileage

I'm runnin' autolite 5125 copper plugs. I got maybe 20k miles on the last set and there real white with tips starting to melt. Would this indicate lean burning or somekind of problem or is everything normal?
bjr23

 

that is not normal. it's too hot for the plug. check the plugs heat range, overadvanced ignition timing, lean fuel fixture, insufficant engine cooling, sticking valve, ect.

by the way Welcome to FTE!

 

Not sure what you mean by tips starting to melt, but 20,000 miles seems to be a lot for copper plugs in the 300. I ran a set 22,000 miles (manual says change every 30,000) and they had seen better days. While they were operating correctly, the electrode tips were rounded off pretty hard on one side and the electrode on that side was all blackened down to the porcelain.

INLINE SIX POWER! '95 F150 XL
300 Cubic Inches of Low RPM Truck Torque! And twin-I-beams too!
"Drive a stick young man! There'll be time for automatics when you're old and unable."

 

TallPaul, were you running the recommended autolites? I ran mine from 45k (when I bought the truck) to 87k and they were still passable (89 F150). They were rounded off, but not slanted and it still ran well.

As for the suggestions on what to do, Vampiro has it covered


-=Whittey=-

 

That's pretty normal for the EFI engines. These thing run really lean. Try a full tune-up, with plugs, wires, cap, rotor, and filters. You should always change the oil when doing a tune-up too. Check them again in about 5-6k, and see if they have worn. I have an older engine, and an aftermarket ignition, so I change my plugs every other oil change. I run a .060" gap!

Jared

 

>TallPaul, were you running the recommended autolites? I ran
>mine from 45k (when I bought the truck) to 87k and they were
>still passable (89 F150). They were rounded off, but not
>slanted and it still ran well.
>
>As for the suggestions on what to do, Vampiro has it covered
>
>
>
>-=Whittey=-

Thanks Whittey. I have been running Motorcraft. When I replaced the Motorcrafts at 22,000 miles the truck seemed to perform better (that without any other changes). Not sure if my hard driving is eating them up faster or what. Just pulled the current plugs at 12,500 miles and they seem pretty good with slight rounding of the electrode, but still the black all the way down one side. A few of them had a black coating (carbon) on the metal base (but not the porclain). All in all they looked fairly good, but since I had them out I went ahead and put new ones in. Seems peppier, but that may just be a figment.

(If it appears I don't know what I am doing, it just may be because I don't, but why pay a mechanic to bollix up what I can bollix up on my own for free)