Stock spark plugs

gtcobra302

Member

Sep 6, 2005

118

1

16

Centra Florida

Sep 30, 2009

#1

• Sep 30, 2009

• #1

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

That is…until I whipped out my Bissell

Mod Dude

Feb 18, 2001

43,216

17,899

224

Massachusetts

Sep 30, 2009

#2

• Sep 30, 2009

• #2

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

 

gtcobra302

Member

Sep 6, 2005

118

1

16

Centra Florida

Sep 30, 2009

#3

• Sep 30, 2009

• #3

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

That is…until I whipped out my Bissell

Mod Dude

Feb 18, 2001

43,216

17,899

224

Massachusetts

Sep 30, 2009

#4

• Sep 30, 2009

• #4

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

Advanced Member

Jun 1, 2005

1,761

63

69

indianapolis/ valdosta ga

Sep 30, 2009

#5

• Sep 30, 2009

• #5

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

Member

Sep 6, 2005

118

1

16

Centra Florida

Sep 30, 2009

#6

• Sep 30, 2009

• #6

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

 

Mustang5L5

That is…until I whipped out my Bissell

Mod Dude

Feb 18, 2001

43,216

17,899

224

Massachusetts

Sep 30, 2009

#7

• Sep 30, 2009

• #7

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

Member

Aug 11, 2008

254

4

19

Sep 30, 2009

#8

• Sep 30, 2009

• #8

Motorcraft replacements, or Autolite 25's.