1997 Mercury Mountaineer 5.0 plug and wires choice

[allmyEXes]

After 21 years and 253K miles on the MM 5.0 it is time for new plugs and wires. I see from the parts suppliers that the Motorcraft wires have the heat shields made on them. I assume these are the best choice. What are the best choice of plugs that will hold up and not have to be changed for a while ? The "Tune up" job looks like a real "bear" and I don't want to have to do this again for a while. Thanks for any advice.

 

[koda2000]

Motorcraft wires are the best choice, though I recently installed a set from RockAuto that were very good and had the heat shields where they are needed. I don't recall the brand off hand (I'll check and edit).

As far as plugs, Motorcraft or Autolite (same manufacture). I recommend double platinum minimum and iridium is even better. You'll find the driver's side plugs will be worn out due to the "wasted spark" while your passenger side plugs will still look very good by compassion. Gap to .054.

Edit:
Denso wires. A little less expensive than the Motorcraft and that's what my daughter could afford. Good quality. Sets for cast iron or tubular headers.

FYI - Changing the plug wires and routing them like the originals (with all the wire holders) is quite the PITA. Took us about 1/2 day. Take pictures and note that all the plastic wire holders that are attached to the engine lift off, so don't try to release them before the wires are off. Going through the wheel wells makes the job somewhat easier.

 

[410Fortune]

Interesting Koda I have not had luck with the irridium plugs and went back to the Motorcaft double platinum

For wires I have had very good luck with Taylor 8.8 wires on my own trucks and these Packard wires for customers/family trucks ($35-42!!)
https://www.rockauto.com/en/moreinfo.php?pk=1133441&cc=1304435&jsn=458

https://www.rockauto.com/en/moreinfo.php?pk=1133544&cc=1304435&jsn=459
very very good wires for the $$$$

I do not run the metal heat guards, instead I use the fiberglass socks/boots

I do not route my wires up along the valve cover like ford does, instead I route them towards the fender skirts keeping them well away from the exhaust

I do not cross the wires instead they run together in a line

Ford had a TSB about 5.0L misfire due to crossing specific wires...

 

[koda2000]

@410Fortune I was amazed at how worn out my driver's side Motorcraft double platinum plugs were after only 60K. No way they would have lasted the Ford suggested 100K! There was basically no electrode left above the insulator on the driver's side plugs and the gap was too large to measure (.080?). The passenger side plugs were almost still perfect after 60K. I'm assuming iridium plugs would have lasted longer, perhaps not. For the future I plan to replace at least the driver's side plugs at around 50K, assuming my trucks live that long.

As far as the metal insulators on the plug wires, my OE plug wires did not have the insulators on every wire (cast iron headers) and the Denso wires matched the OE Motorcraft wires exactly. IIRC there were 4 metal jackets, 2 for each side.

As far as the plug wire routing I figured the original plug wires worked fine routed the way Ford did it from the factory for 235,000+ miles (and probably weren't my misfire issue) so why not route the new wires the same way. Besides, I like things tidy.

Using the wire socks is always good insurance.

 

[CDW6212R]

The plug wires to keep well apart are #'s 5&6, but also 1&3 too. The #6 and #5 cylinders fire in that order, so they need to be separated as much as possible. #'s 1&3 follow each other in the firing order, so those sometimes are prone to cross fire when the wires are very old.

The plugs should be changed way before the 100k interval, having the threads seize to the heads is a worry when they get that old. I like doing them in the 50-60k range, regardless of what the tips are made of. The more basic copper or AL tips will last 40k easily, but it is actually hard to find those plugs these days. I choose the most feasible plug that's easy to get, no rebates to mail in etc.

Be easy removing the plug wires from the plugs, don't yank too hard, it's easy to ruin the plug wires removing them. Go slow loosening each plug initially, hoping not to strip or break one.

I like Motorcraft wires, but as said there are some good alternatives. For a long term keeper, Magnecor are the best insulation quality wires. I have one set of those that are still good after 15 years and 105k miles. Those run over $140 now I think, they were about $125 when I got mine.

 

[koda2000]

As far as removing plug wires from the spark plug w/out damage, I have a tool I've had forever that works great even on the most stuck-on plug boots. It looks a ringed dip stick handle on one end and it has a loop on the business end. It's thin enough to slip into tight areas and loop around the base of the insulator just below the boot. When you pull on the ringed end it pops the boot right off w/out damage.

My trucks receive regular maintenance and GA doesn't salt its roads, so no rust/fozen spark plugs to worry about.