Blue07V6

Prob time to give my car a tune up, not sure what apark plugs to go with, I always used Autolite Platinums in my other Fords (1994 F150, 1969 F-100) and NGKs in my others (Toyota Corolla and Nissan D21) Not sure about my what to go with in my 4.0. id like some opinions/thoughts.

JimC

If you are naturally aspirated then the autolite 5143 is perfect. I had those when my car was N/A, and even on nitrous. No problems at all with them, inexpensive, and they were always in great shape when I pulled them at the end of racing season. You really don't need to spend a lot of money on spark plugs for the 4.0.

red07Pony

You can search the site but Autolite 5143 is the general consensus

2K6V6PONY

I know this is a super old thread but I recommend the NGK G-Power or V-Power plugs for our cars. They work fantastic and the threads, etc are made out of a composite metal that wont degrade and seize up in the cylinder head so you wont have to worry about breaking a plug which is a notorious problem with our cars.

DenIs2Fast4U

Just to add my 2 cents to this also; i would agree that just going with the autolites is perfectly fine for our n/a 4.0's, but i was able to get a set of NGK Iridiums very cheap so i decided to try them. I am very happy with them so far, the car idles very smooth and the throttle response is spot on. I can't say that they provide any benefit over the 5143's but they are definitely a good plug