Best spark plugs for 4.0l

[black_demon69]

Just looking for opinions

 

[adsm08]

Motorcraft double platinums.

 

[Big Josh]

I second the Motorcraft recommendation, and most will agree; this is an easy choice for me. Same goes for the wires.

 

[black_demon69]

Motorcraft is my first choice as well but my second choice is autolite as far as brand for anything Ford and as far as copper platinum or what have depends upon the application.

 

[black_demon69]

What do you think about iridium plugs in the 4.0l?

 

[adsm08]

The iridium plugs don't offer huge benefits for the 4.0. It just doesn't run hard enough to get any real gains.

The biggest thing with a 4.0, or any engine with a waste-spark system, is to make sure you get double platinum, so you are wearing your plugs evenly. If you don't use doubles one side of the engine will wear out twice as fast.

 

[JohnnyO]

What do you think about iridium plugs in the 4.0l?

The last two sets of plugs i put in my 4.0 SOHC were NGK Iridiums. I change plugs every 50k regardless. My observation was that they hold their gaps better than conventional double platinums. I'm happy with them. Main thing on Fords is don't buy multiple electrode plugs like Bosch +2 or +4 that Auto Zone will try to sell you for the reasons adsm08 mentioned.