Spark plug help needed asap

gsp393

Registered User
I've got some new plugs Motorcraft #SP-504 AGSF34FM34 and the threads are longer than the old Motorcraft platnums. Maybe 1/4" longer. I've looked at O'rielly and evey other parts house. Finally I ordered some from Bill at SuperCoupePerformace and they're no dirrerant. Question is, have any of you used them and are there any issues as far as them going deeper into the head?

Thank you very much.
 
Are you saying there are more threads away from the electrode? I think thats what you are getting at. As long as the end of the plug where the electrode is is the same distance to the tappered seat, you are good. In other words your old plugs have a shoulder before the tapered seat and the new ones have threads all the way to the tapered seat.
 
Are you saying there are more threads away from the electrode? I think thats what you are getting at. As long as the end of the plug where the electrode is is the same distance to the tappered seat, you are good. In other words your old plugs have a shoulder before the tapered seat and the new ones have threads all the way to the tapered seat.

The proportions of the plugs are the same but the new ones have about
3/8 more thread than the old ones making them go that much deeper into the heads which I don't want to find out is too much the hard way.
 
They won't go deeper. The tapered part where the plug gets bigger is what stops it from going deeper into the head.
 

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They won't go deeper. The tapered part where the plug gets bigger is what stops it from going deeper into the head.

Thanks for the drawing and advice. That's also what the guy at O'rielly said, so this weekend I'll measure the older plug next to the new ones.
 
Ford redid all their spark plug part numbers about 6 years ago, consolidated them. The old plugs you have AWSF are black and the new ones AGSF are silver. I found an old AWSF 44 C in my tool box, which is the same as a stock SC plug but just copper. It has the short threads you are talking about. I'll post some pics of them later.
 
Ford redid all their spark plug part numbers about 6 years ago, consolidated them. The old plugs you have AWSF are black and the new ones AGSF are silver. I found an old AWSF 44 C in my tool box, which is the same as a stock SC plug but just copper. It has the short threads you are talking about. I'll post some pics of them later.

I checked them side by side today. You're right.

Thanks
 
Good deal. Here's those pics I promised.
 

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