Which Autolite spark plugs to get

[ncyrider]

For spark plugs on the 4.0 I heard Autolite double platinum is the way to go, and after searching a Ranger 4.0 forum I found out Autolite APP5144 is the one to get. But after searching RockAuto's website, the only Autolite DP plug they have for my 2001 4.0 SOHC is APP103. I thought the Ranger 4.0 is the same as the Sport Trac's. Which Autolite plug should I get?
And for wires, I'm guessing Motorcraft (WR6120) is probably the best?

 

[briwayjones]

I didn't know they had different Autolite DPs that fit the 4.0L. I would get which ever you can get. And unless you get some performance aftermarket wires then Motorcraft are probably the best and you can't go wrong with them. You want at least 8mm wires though. I'm guessing all decent wires for the 4.0L will probably be at least 8mm.

 

[swshawaii]

Hard to fault the Motorcraft SP500 FineWire Platinum, haven't heard a single complaint or issue when used on the 4.0L SOHC. They are an upgrade and direct OEM replacement from the superseded AGSF22FM/PP plugs that came from the factory. Autolite XP103 Iridium or APP103 Double Platinum are also good alternatives. The key is using replacements that are designed for your engine and specific heat range. Check gap at .054, very thin coat of copper or nickel anti seize on the threads, and you're good for a minimum of another 70,000 miles. OEM Motorcraft wires are as good as any for stock replacements, nothing gained by expensive performance wires on stock engines.

https://www.rockauto.com/catalog/moreinfo.php?pk=949946&cc=1366680
https://www.rockauto.com/catalog/x,carcode,1366680,parttype,7212

 

[ncyrider]

Read this on a Ranger forum...

You will want to use the appropriate Autolite double platinum plug for your application. As for the "and why?", it's because Ford uses a waste spark ignition system. Unlike most four stroke engines where the plug fires once every two revs, the Ford 4.0 fires every rev. This because there are three iggy coils built into one unit (assembly); one coil serves two cylinders and those two are one rev apart as far as the four strokes goes. And on top of this, the plugs not only fire every rev, but because of how the system is wired and how it works (each side of the secondary winding in a coil goes to the center electrode of a plug; ordinary 4 stroke one side would go to the center electrode and the other would go to ground), plugs on one bank fire from the center electrode to ground and the plugs on the opposite bank fire from the ground to center electrode.

 

[briwayjones]

good information

 

[crash594]

I never have any luck but with motorcraft. That's what it was designed for and that's what I stick with never had an issue.

 

[briwayjones]

I never have any luck but with motorcraft. That's what it was designed for and that's what I stick with never had an issue.

Autolite made motorcraft plugs in the past if they don't still.