Stock spark plugs

[gtcobra302]

I have a 1991 auto lx 5.0 that is ALL STOCK. I bought it friday, it has Autolite ap25 platinum plugs in it. I have always heard that platinum plugs get hot and stay hot thus they should not be used. Is that true? If it is true what are some good daily driver, stock type plugs? What should they be gapped at?

 

[Mustang5L5]

Stock OEM motorcraft copper plugs gapped @ 0.052" - 0.056"

 

[gtcobra302]

Is that true about platinum though? I am really looking for the best gas milage and I figure stock plugs were the way to go. True?

 

[Mustang5L5]

Platnium has a higher resistance to electricity. The only reason to really use platnium is if you want to go 70K miles without changing your plugs. No other benefit to plats.

5.0s's tend to detonate and run "crappy" with plats. The stock ignition was designed for copper electrodes.

The only material more conductive than copper, are silver spark plugs. If you don't mind changing plugs every 15-20K, copper and/or silver is the way to go.

Now if you start getting into power adders, iridium plugs would be my recommendation.

 

[Mr. Rustypwnz]

get some autolite 25 plugs I've gotten 27mpg in a 5.0 wit these plugs. the only thing better I would say would be to get some ngk plugs they are awesome..

 

[gtcobra302]

So I pulled one plug and the porcelain looked good a touch of orange, the electrode was white, like burned white.

 

[Mustang5L5]

Without pics, tough to say. You could be running a tad lean, but that could be from other causes..not the plugs. Have you run your codes lately?

Typically spark plugs are given way too much credit when the car runs great and way too much blame when it runs poorly.

 

[Coast2CoaStang]

Motorcraft replacements, or Autolite 25's.