Still confused about proper spark plug type

[roswell998]

It will be appreciated if Scott Patterson also replies to this since he had given a very detailed analysis at some earlier date about the issue related to erosion of the plugs anodes and cathodes because of the reverse polarity as a result of the coil firing the plugs in pairs.

In a nutshell, he stated that it was necessary for both the anode and the cathode to be plated (it seems that the original plugs had 3 with anodes plated and 3 with cathodes plated and it was critical which cylinder each was installed in).

INFO THAT HAS BEEN RECENTLY SEARCHED:

Before replying, please follow the link below and see for yourself what I describe.

If you go to www.motorcraft.com and follow the menu choices to plugs for the '93 SHO (probably any year with Yamaha engine), clicking on the standard plug brings up the AGSP32FM as an standard service plug (which is what most people on this forum recommend).

HOWEVER, if you click on premium/platinum plug rather than standard plug it will show a chart with the AGSP32P-P (or AGSP32PPF6) as a double platinum plug and the AGSP32FM is shown as an alternative platinum plug.



BOTTOM LINE..........If the AGSP32FM is a single platinum plug with only the anode plated, do we run risk of premature failure because of excessive cathode erosion on the three which are operating in reverse polarity? If not why does motorcraft.com specifically list them as "standard" duty and then list the AGSP32P-P as "premium duty"?

Your responses will be appreciated!

 

[revhardSHO]

Click Here For Correct Spark Plug Set

You want the AGSP32FM Motorcraft Spark plug set @ $23.94

 

[Rockledge]

roswell998,

You will also find the FM's listed under the SPARK PLUG, PREMIUM/PLATINUM section when doing a search on Motorcraft website.

If you recall, before the FM's came out, the PP's were listed under BOTH Standard and Premium categories. So nothing has really changed in that regard.

Your point(s) about the FM's being constructed differently are well taken. Obviously the jury is going to be out a while until we know for sure about these FM plugs. But there is some cause for optimism, at least based on some of the feedback I have gotten from a credible source or two. The following is a post of mine a while back in response to a question asking whether the new FM plugs were the same thing as the PPs:

I’ve seen some things posted about them being the same exact plug but with a different part number. On the other hand, I’ve come across some other information that leads me to believe that it might actually be a whole different plug. It has come to my attention that, at least with respect to some of the applications usually calling for DPs, Ford is now recommending Motorcraft’s newer "fine wire" design plugs instead which are supposedly even better than the DPs, especially with respect to the Ford EDIS ignition.

This is an excerpt of an email I received from a friend of mine who is an engineer with IBM and who also drives a Ranger (among other things).

...I meant to tell you, when my wife and I were at SEMA week before last, I visited the Motorcraft booth, and had a lengthy discussion with a Motorcraft rep. with my experience with the Motorcraft double platinum plugs for my 3.0L FFV (I'm sure you have seen my posts on using AGSF12PPs, instead of the AGSF22PPs, a hotter plug that Ford is now recommending). The Motorcraft rep. recommended a new platinum plug, a "fine wire" plug (AGSF12FMF6). Sometime ago, I got the e-mail address of an engineer at Motorcraft (James Power), so I sent him a note asking him about the new Motorcraft "fine wire" platinums. He talked very positive about the new plugs (I'll forward his e-mail to you...).

Here is the email from the Motorcraft engineer that he is referring to:

...Fine wire means a .030" to .040" dia platinum nickle alloy rivet welded to the end of the center electrode. There is about three times the precious metal than what is found on a 'P' level enhancement. The P's are made by crushing and welding a small special lump of Platinum nickel so that it is a disc about .003" thick.

The effect of the point on the center electrode is reduction of required firing voltage and that aspect slows down the erosion of the sidewire. Consequently, we can use a single 'finewire' enhancement to replace the double 'p' designs for service and get the same durability.

Some auxiliary advantages of the reduced firing voltage is less stress and therefore better life of coils and wires, etc. and cold foul misfire is improved. Don't go crazy getting some because our systems are robust without it and the improvement is modest and mostly unrecognizable except for special cases. We use it in production as a durability measure for those engines that wear out plugs fastest.

So, from that it sounds to me like we have a new generation of plugs (Fine Wire) that will be replacing the Double Platinums

Scott (sdpatt) pointed out some things in response to my post quoted above:

I had previously read...the discussion about the new fine wire Motorcraft plugs, but they only mentioned a nickle platinum tip on the center electrode and the allowed "reduction of [the] required firing voltage." Since we can't dial down the firing voltage of our systems, and three of our plugs fire from the side wire to the center electrode, the high voltage ignition system on our SHO engines is going to quickly erode the unprotected side wire on three of the six plugs. I am NOT sold. Caveat emptor. Let the buyer beware.

I followed up on Scott's comments and got some more feedback from my original source(s):

Hi Scott,

I passed along the points you raised about the new Motorcraft fine wire plugs to some people who who are also interested in the issue. They are the same people who have been my sources of information on this subject. Here is a response that I got from one of them:

Hi Joe,

Your SHO forum friend brings out a point ....that has been the argument all the time for using DP plugs with EDIS!

I raised the same question with the Motorcraft engineer, and I'll try and explain his response. One thing to understand first, when a coil "discharges" (due to the induced field from the coil primary into the coil secondary), the voltage will only build up until the spark occurs, and will not increase any more. There are several parameters that effect the voltage required for the plug to spark. In addition to the gap, and pressure/composition of the cylinder charge, the physical structure of the plug electrodes also determine the spark voltage. A "blunt" electrode requires a higher voltage to spark, than a "sharp" electrode. With the "fine wire" center electrode being sharper than the platinum bead on the older DP plugs, the spark voltage is lower with the new "fine wire" platinum's. With this lower spark voltage, there is less energy, so electrode erosion is reduced. Because of this, platinum is not needed on the outer (GND) electrode. I'll keep an eye on mine to see how they do!!

I hope this answers the question on why only the center electrode is platinum on the new "fine wire" plugs. As explained by the Motorcraft engineer, there are several side benefits to the lower voltage:

1) lower misfires
2) longer coil pack life
3) longer plug wire life

These points alone are reasons NOT to increase the plug gap wider than the recommended gap. I have seen many posts about gapping plugs wider than the recommended gap!

Thought you might be interested.

So, that's the scoop (as I know it) on the new Motorcraft FM platinum plugs.