Spark Plug Question

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Apr 29, 2008 | 08:04 PM

Spotty

Thread Starter

Laughing Gas

Joined: Jan 2006

Posts: 1,098

Likes: 11

From: Minnesota

Spark Plug Question

Most of us know about the 4-5 threads in most of these heads for the plugs. When I did my 98 F-150...4.6 at 100,000 miles I used Autolite PP plugs. They had the typical 5 threads. I have a 97 Mustang GT that I rarely drive, but thought I would do plugs, since it had the originals. I bought Motorcraft PP plugs, got home, went to put the first one in, noticed it had a least 10 threads. I looked at the old plugs and notice that the new plug and the old plug is the same distance from the seat to the electrode. Hence, same depth, no problem. But... I called the auto parts store and the guy insists this is to prevent blowout because now it grips all the threads. I have never seen one of these heads, but I assume there are only 5 threads down at the bottom, then a blank area, then the seat. He insists I am using more head threads... I just don't buy it. Anyone know for sure what's going on here?

Spotty

Apr 30, 2008 | 06:22 AM

Ron W.

Elder User

Joined: Jan 2008

Posts: 589

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From: Stockton Ca.

Ford superceded the AWSF prefix to the AGSF prefix on their Motorcraft plugs, and I always reccomend Motorcraft for Fords. The Autolite name was sold to Fram/Bendix/P&D corp. way back in the 70's.

This will explain better, has pictures...

https://www.ford-trucks.com/forums/5...rt-change.html

Apr 30, 2008 | 07:11 AM

Spotty

Thread Starter

Laughing Gas

Joined: Jan 2006

Posts: 1,098

Likes: 11

From: Minnesota

Thanks Ron... Just what I thought, the head only has 4 or 5 threads regardless of the number of threads on the plug. Thanks for the linky.

Spotty

Apr 30, 2008 | 08:41 AM

galaxie641

Postmaster

Joined: Nov 2006

Posts: 4,517

Likes: 3

From: SE Wyoming

I believe the reason they added the threads to the plug is for the newer 8 thread heads, obviously they do nothing for the old 4 thread heads, but the can still use 1 plug for both heads.