Spark Plug Fun/Query
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Laughing Gas
Joined: May 2004
Posts: 1,062
Likes: 6
From: Dallas, TX, USA
Spark Plug Fun/Query
As a refresher, this is on my 1986 F-150 4x4 w/302 and an AOD.
I decided to change the plugs on my truck, so I looked at the sticker on the radiator support. It said that I needed Motorcraft ASF-32C plugs, so I purchased a set of eight and set to work. I soon discovered that the plug does not fit the engine. I read the manual and discovered that there is also an ASF-42C plug that is recommended. It doesn't fit, either; it is merely a different heat range. There's also a couple of other part numbers for the 86 mentioned in the documentation I've been able to find. None of them will fit in the head.
http://www.dallasdrivers.org/albums/...0530.sized.jpg
On the bottom is the ASF-32C. On top is what actually fits this engine.
The old plugs had a thick, hardened crust of black oil and crud covering their maker and model markings. I finally just worked at them for a while with a knife and got a usable Autolite number, which crossed to a Motorcraft AWSF-44C; this is displayed on top. This plug is NOT supposed to fit the '86 302 or a 351 that I can tell.
Yes, the engine appears to be original to the truck - at least the numbers match the build sheet I recently obtained. I don't know what quality was job 1 at Ford when this truck was built, but it sure wasn't documentation quality.
Does anyone have any idea why the spark plug design doesn't even remotely resemble the ones supposed to go into the truck? Or perhaps what heads were installed at some point?
I decided to change the plugs on my truck, so I looked at the sticker on the radiator support. It said that I needed Motorcraft ASF-32C plugs, so I purchased a set of eight and set to work. I soon discovered that the plug does not fit the engine. I read the manual and discovered that there is also an ASF-42C plug that is recommended. It doesn't fit, either; it is merely a different heat range. There's also a couple of other part numbers for the 86 mentioned in the documentation I've been able to find. None of them will fit in the head.
http://www.dallasdrivers.org/albums/...0530.sized.jpg
On the bottom is the ASF-32C. On top is what actually fits this engine.
The old plugs had a thick, hardened crust of black oil and crud covering their maker and model markings. I finally just worked at them for a while with a knife and got a usable Autolite number, which crossed to a Motorcraft AWSF-44C; this is displayed on top. This plug is NOT supposed to fit the '86 302 or a 351 that I can tell.
Yes, the engine appears to be original to the truck - at least the numbers match the build sheet I recently obtained. I don't know what quality was job 1 at Ford when this truck was built, but it sure wasn't documentation quality.
Does anyone have any idea why the spark plug design doesn't even remotely resemble the ones supposed to go into the truck? Or perhaps what heads were installed at some point?
Senior User
Joined: Sep 2004
Posts: 176
Likes: 0
From: Waynesboro, PA
Well, it sounds to me like there might be a difference in the heads that could possibly be on your truck. Personally I run autolite Platinums and even though my truck is the 1983 with the 302, I found that my engine takes the Autolite 46, which is a larger plug unlike the narrow AP25 that you have pictured in the link. You may want to find the motocraft equivalent to the AP46 and try that.
Thread Starter
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Laughing Gas
Joined: May 2004
Posts: 1,062
Likes: 6
From: Dallas, TX, USA
The Autolites I took out were (I think) 2425's. Anyway, the top ones fit and work just fine (the AWSF-44C's). The ones you mentioned are too large to fit.
Last edited by Spktyr; Sep 28, 2004 at 07:24 PM.
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