94-95 COBRA Spark Plug Scandal

[302 COBRA]

I'll put on my flame suit for this one. I'm confused. I want Motorcraft plugs in my car. Car is 94 Cobra with GT-40 Iron heads.

The plugs I pulled out were Motorcraft plugs. They were half thread.
The car ran like a beast for many miles with the original plugs. No issues.

The equiv. plug is AGSF-32C. This is a Motorcraft FULL THREAD plug. There is no half threaded plug.

I bought a set, and the plugs will not thread all the way down into the head. I cannot see how this makes any sense. The sealing surface of the plug is nowhere near the plug hole when plugs are torqued down.

I called Ford, and got some "don't worry about it" type response. If my heads are not full thread, and I opt to use OE stuff, Ford says to use a fully threaded plug, and the threads will function as a seal?

I've been running Autolite 764, which is a half thread plug ( like OE plug without Motorcraft stamp )... but I'm a little cheesed off about the Ford thing.

My question is, can someone with FIRST HAND knowledge let me in on the secret? Have I been living under a rock? Just need to hear someone else say, "hey, that dosen't make sense from a design standpoint."

I'd appreciate answers to my question, not suggestions to keep running the Autolites and forget it. :lol1:Thanks

 

[stangbanger856]

Wrong section, should be in the SN95 tech section. But ill.attempt to answer anyway. The full plug wont go all the way in because thebother half of the threads that are normally not used ( with half threads) is packed with carbon and grime that has accumulated over time. So when you install the full thread plug it hits this buildup and wont go any farther. Take the plugs out and spray some carb cleaner to break it up and let sit for a few mins so the cleaner can dry out. Then run a thread chaser to finish it off.

Ford GT40 heads spark plugs are taped all the way threw and only reason it would bottom out is because the spark plug has hit the piston wich is HIGHLY unlikely.

 

[bdcardinal]

According to my lookup that is the correct number, although most dealers use the short numbers now, not the AGSF numbering system.

 

[kevinatfms]

"i did not have sexual relations with that woman"

 

[Filthy1]

Don't know if this will help any...its worth a shot though.

nitrous plugs quick reference guide - Ford Mustang Forums : Corral.net Mustang Forum

 

[Boomer182]

Autolites are fine plugs IMO, as stock replacements. I have used them in many of my vehicles over the years.

 

[302 COBRA]

Wrong section, should be in the SN95 tech section. But ill.attempt to answer anyway. The full plug wont go all the way in because thebother half of the threads that are normally not used ( with half threads) is packed with carbon and grime that has accumulated over time. So when you install the full thread plug it hits this buildup and wont go any farther. Take the plugs out and spray some carb cleaner to break it up and let sit for a few mins so the cleaner can dry out. Then run a thread chaser to finish it off.

Ford GT40 heads spark plugs are taped all the way threw and only reason it would bottom out is because the spark plug has hit the piston wich is HIGHLY unlikely.

The reason I'm so freaked out is that the OEM was half thread. The full thread "superceeded" the half thread as per Ford. I was given a link that explained the reasoning behind it.

I see your logic about the carbon build up, I'll take another look, but again, your logic doesn't make sense to me.
Car ran very well for 60k with plugs that were backed halfway out of the cubustion chamber?

Thanks for your time, stangbanger, and thanks to everyone else who answered. I'll be sure to take another look.

 

[302 COBRA]

According to my lookup that is the correct number, although most dealers use the short numbers now, not the AGSF numbering system.

Thanks for taking the time to look it up. Interesting about the numbering system. Dealing with Ford counters to get parts for a bastard 5 liter Cobra that I'm trying to keep mostly stock has been an adventure.

:bash:

 

[bdcardinal]

Thanks for taking the time to look it up. Interesting about the numbering system. Dealing with Ford counters to get parts for a bastard 5 liter Cobra that I'm trying to keep mostly stock has been an adventure.

:bash:

Believe me, I just picked up a 95 GT a month ago and I have been exhausting my resources trying to find parts for it.

 

[me32]

Are you having problems with the new plug? The added threads should actually give a better combustion.