Would anyone happen to know if the design of the SP-514 spark plugs are a one piece design, or are they the same two piece plug with an updated part number ? I tried doing a google search and could not find any comparisons between the SP-514 over the previous SP-462 that Ford replaced it with

 

It is a one piece design that replaces the problematic design of the first factory plug.

 

When did this plug come out?

JR

 

From my understanding, it's been out awhile now as the previous SP-462 part number is no longer available.. However I did look at the SP-514 plug at my local dealership today and it seems to look as though it's still a 2 piece design plug

 

The design still looks the same but its the internal that is supposed to be different.

 

Hey Trent ! by any chance would you happen to know which part of the internal design is different.. Thanks much, Rocky

 

I'm not sure because I haven't had one break on me yet lol. I'll see if we have an old one lying around in the shop and ill bust it open and take a look ill take pics so you can see too

 

Hopefully your comparision pics will confirm they're a one piece designed plug and if they are ? Ill be having the old SP-462 plugs replaced soon enough

 

How many miles are on your car?

 

20,848 miles

 

Anyone know if the newest SP547 plugs are any good for a 2005 GT? I can find SP514 which I believe replaced the SP462, but SP547 shows as a replacement for both. SP514 are listed as nickel while SP547 are listed as platinum.

 

After doing a google search, the SP547 spark plugs are Ford/Motorcrafts improved design over the previous SP514 which supposedly are less prone to breakage. However, they remain unchanged as a 2-piece design and are made in Mexico. Therefore I would stay as far away from these plugs as possible. IMHO this is just another fine example of Ford's marketing hype at work lol.

 

Thanks for the additional info. I thought the electrode was different in them, but I've seen boxes of SP514s marked with 'finewire platinum' so who knows. I'll pick up a set of 514s.

 

Personally, I'm not fond with any of Ford/Motorcraft's 2-piece design spark plugs. If my car didn't require one degree colder spark plugs, I would've made the switch over to MSD's 1-piece design plugs. However, being that my car is FI and requires a one degree colder spark plug, I use nothing but Autolite HT0 spark plugs, despite being a 2-piece design.

 

My car has a JLT intake and tune, but no FI. I've been leary of using any plugs other than the motorcraft ones - do the MSD's run well in NA'd 2005's?

 

Just knowing their a one-piece design plug and having piece of mind that they won't separate/break when it comes time to change them, would be more than reason enough for making the switch. Also, MSD has been in the performance industry for many years and has an excellent reputation for producing top quality products. The bad news however is, the MSD spark plugs are only available in Iridium and not platinum. Therefore if that happens to be a deal breaker for you? Then you might want to consider sticking with OEM Motorcraft

 

I went through this with my '07 FX4 with 5.4 - 3valve which came with SP507s, which I had bought SP515s for, but then bought SP546s last year, it had 67,xxx miles.
The 515s had more bluing at the weld, the 546s looked different in the way the ground electrode was made / attached, but I measured the barrels of all 3 and they all three are 10.0 mm. which is 0.393701" which is pretty close to the 0.393 - 0.394 range I interpolated it to on the SP515 and SP546 plugs new in box. So "diameter" looks unchanged.

I did note that the sealing taper or step down on the SP-546 plugs is somehow "more pronounced" but not sure what it means. No bluing. I hope that it means the lower shield is better attached … or maybe one with upper plug body.

I did find that the top of the plug where the coil spring rested was longer at it's seat for the coil so it applied more pressure against the coil. I put the SP546s in my '07 FX4. I had two plugs screw up upon removal in my truck, the #8 all the way under the firewall pulled the outer shell and left all the porcelain & center stuck and it was the hardest to get to. I used a Lisle tool set & Porcelain Puller for an easy fix. In the '08 Mustang GT, #8 will be easy to get to.

I suspect the same changes were made with the plugs in the 4.6 - 3 valve, just in a different heat range. Truck's been perfect ever since. The Mustang has much easier access. I had a really long 6 point 9/16" plug socket a couple years and I bought a Carbyne 9/16" magnetic Spark Plug Swivel Socket as I didn't yet have one. …....and it was great, I used it mostly. Strong magnet too.

 

Old thread but useful information.

 

IT'S ZOMB...

*...looks at dates closer...*

...oh, it's only a yearish old resurrect. Eh.

/But yes, indeed, good info. May I also point out that using nickel anti-seize regardless of plug is probably a good move given how that shroud works in the head?

 

Yeah, I knew the thread was initiated a lot longer than a year ago, I knew that there was some activity last year too, I know too that my '07 FX4 5.4-3v takes different plug numbers than the 4.6-3v in our '08 GT, but the plugs look to be made the same and have gone through similar updates. Thought a look at the changes would maybe help someone. I know the Lisle tools work for either as well. If a plug breaks, follow the Lisle Tool directions, it's engineered to do exactly the job.

Yes, my new plugs in the 5.4-3v got a thin smearing of nickel anti seize on the barrels & threads.