So after 100k miles i've gotten around to changing my plugs. NAPA sold me Bosch 7580 (HR 9 DCY) which is also what Bosch plugs website calls for and a few other sources on the net. The plugs that came out of the motor were Motorcraft AGSF 34EG which look a lot longer and have a gap of around 4mm. I did a quick search of this plug application and it lookes like it fits some Ford cars. What is correct? Both have the same thread pitch and use 5/8" socket. I bought the truck with almost 50k on it from a dealer used so who knows if they are original.

Any thoughts?

 

Hate to say it but it doesn't look like anyone changed the plugs, unless they replaced them with the exact same type. Were they in good shape still?

Don't know anything about those Bosch, I just use Platinum 4+, no gapping.

 

Bosch is a good plug. I have used them and had no problems.

Make sure the thread depth is the same.

 

They look like they could be 100k old. The ground electrode is worn as well as the electrode itself. http://www.motorcraft.com/default.asp?menuIndex=1 calls for AGSF42FM as stock and the owners manual calls for AWSF42EE which is neither that i have. Any idea what the letters and numbers stand for?
Thanks
Dean

 

See that's the problem i face. The new plugs are a bit shorter by a few threads but everything i read for this motor calls for them. I mean, how many styles of 4.2 V6 do ford make? Maybe i have the wrong engine, after all it's never leaked coolant!
Dean

 

Do yourself a favor and go back with the factory recommended Motorcraft plugs. You'll be glad you did!

 

I agree woth blue oval. Just replaced the ones on my 99 taurus. The plugs I picked up at auto zone had more threads than the origional ones but the distance from where the plugs contacted the cylinder head to the end of the plug was the same. They are the Motocraft plugs the book called for. I installed them and the car runs great...Kevin

 

Who makes the Motorcraft plugs?

 

I believe Motorcraft is a Ford brand. As to who actually manufactures it, nowadays w/ brand stamped products coming from anywhere but the US, who knows.

 

Allied-Signal makes Motorcraft plugs to Fords specifications.And yes,they make Autolite plugs too.But,they are not the same plug as Motorcraft plugs are.How do I know this? I contacted Autolite and they gave me this information.
www.autolite.com