I was told today in a shop that does mostly Mustang performance work that Motorcraft spark plugs for the 4.6 engine (SP547) have been redesigned and are now ONE PIECE. Is this true?
I have been using Champion one piece plugs for several years, with no issues, but if Motorcraft plugs are one piece, I would go back at next plug change. I have heard rumors for years that they were going to go to a one piece design but I want to be dam- sure before I go back to Motorcraft plugs.

 

I am totally confused. Some places I see say the SP547 are one piece, others say they are still two piece. What is the truth? I would like to go back to Motorcraft, but not to a two piece crap plug.

 

Apparently the cathode is welded to the anode so although the SP547 is technically a one-piece plug, it's actually made from two pieces welded together. Other one-piece plugs are probably made the same way so I'd have no worries about using the SP547.

 

Thanks Dino...

 

Actually the Champion are a true one piece. The long cone on the champion is all one piece with the rest of the shell. You can see it here and it’s the same as I recall when I installed them twice in my car so far. https://www.jegs.com/i/Champion+Spar...iABEgIgrfD_BwE

From what I read of the “improved” sp547 when they first came out from the truck forums is, The motorcraft SP 547 is identical to the problematic SP 514 they replace and are still two piece. The enhancement on the SP 547 is that instead of relying on just a crimp like the first gen sp 514 plug, they add a weld point or two to the shell to body seam to better secure it to the rest of the body to reduce the chance of separation. I’ll see if I can find the links to the posts. Regardless you can still see a clear separation/seam of the sp547 cone to the rest of the body. Just look up the images.

Im sticking with Champion.

 

Yea, in light of what I've read about the "improved" Motorcraft, I think I'll also be staying with Champions.
I am truly amazed that in light of all the problems with these 2 piece "Motorcrap" plugs that Motorcraft hasn't bitten the Bullitt and redesigned these plugs. I suspect that by doing this, they'd be admitting they made a bad plug and open the door to legal action. Too bad, this was a real black eye for Ford.

 

Do you have to gap SP547 plugs? Or are they gapped at the factory?

 

I've been using the Champion 7989 spark plugs in my 07 GT since 2009 and have had zero problems with them. I'd stick with a proven winner.

 

I've been using Champs for several years with no issues. I am now getting a bit of a rough idle but no codes. I have read these new Motorcraft SP547 plugs are redesigned and work well, so I'm going to try a set.

 

As I said in your other thread, I put the Motorcraft plugs on mine, had no issues getting the old ones out when I purchased the car. They do great, performance-wise, took it to the local track and had a blast.