I have AC. R42TS spark plugs in my 1991 ford f150 truck with the 5.8l I heard that they were not recommended to use is this true or not.

 

a/c delcos in a ford is not a good idea, i'd recommend using motorcrafts or autolites, and whatever you do, do not use champions or boschs either.

 

I might be wrong but i got the spark plug #ASF- 32Cfrom under neath the hood and type it in onrockauto.com the websitessaid there werediscountined. Does this meanI can't get the original plugs for the truck anymore. If not what would be the best kind to get.

 

This is no help, just an observation that that is aggravating as all hell. That sort of thing has happened to me a lot over the past 30 years. Oh yeah, make sure you check the center electrodes on -any- plugs you buy. Two years agoone dropped out on mecausing a hot-spot that burned thru a piston.

 

If the AC plug # crosses to a Motorcraft or Autolite equivalent the don't worry bout it. Kinda make me winder why people think plugs are smart enough to know what kinda car they are going in. If the heat range is the same what else changes. Plugs work on simplee technology the spark travels from wire to elecrode and completes the arch through a ground that is calibrated for the gap. Anyone that can help me answer the other question. How does ones car identify what manufacture of spark plug is being used.