Advice about plug gap
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Joined: Nov 2010
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Advice about plug gap
I want to change the plugs in my F150 (2003) 4.2L V-6. I bought replacement Motocraft SP-504 plugs from a parts store. They and their website recommended a gap of.044 for the plugs. The owner's manual and vehicle emission sticker under the hood recommend .052 - .056. The Haynes manual recommends .054.
Who's right? I'm leaning with the .054 since I have the Haynes manual, the owner's manual and vehicle emission sticker all appearing to be in agreement.
Also, I see varying opinions about anti seize compound on the plug threads and whether to torque or not. Haynes says to torque to 15 ft/lb if I remember correctly (will have to check again).
Any advice is appreciated. The work I can do. That's why I don't want to pay someone to do this. I just need to get to the right answers before I do it.
Thanks
Who's right? I'm leaning with the .054 since I have the Haynes manual, the owner's manual and vehicle emission sticker all appearing to be in agreement.
Also, I see varying opinions about anti seize compound on the plug threads and whether to torque or not. Haynes says to torque to 15 ft/lb if I remember correctly (will have to check again).
Any advice is appreciated. The work I can do. That's why I don't want to pay someone to do this. I just need to get to the right answers before I do it.
Thanks
Thread Starter
Junior Member
Joined: Nov 2010
Posts: 2
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Better late than never but "Thanks". Been a long time since I messed with any of this and wanted to make sure I did it right. .054 works just great. (Even the box for the plugs stated that they needed to be gapped according to manufacturer standards so I have no idea why the .044 gap was even mentioned by the website or the parts house.)
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Joined: Feb 2010
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From: Grand Forks, ND for college; Langdon, ND is home
lol plug gap. if its not a race car don't worry about it, just make sure its not way to big and its good. The only thing a .44 gap would have done compared to a .54 is maybe a lil easier cold starts. Only time you need to worry about gap is if you are running a high horsepower, high compression motor where spark blowout is a problem.
Senior Member
Joined: Oct 2010
Posts: 859
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From: Wyoming
lol plug gap. if its not a race car don't worry about it, just make sure its not way to big and its good. The only thing a .44 gap would have done compared to a .54 is maybe a lil easier cold starts. Only time you need to worry about gap is if you are running a high horsepower, high compression motor where spark blowout is a problem.
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Joined: Jul 2023
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Plug gap n torque
I want to change the plugs in my F150 (2003) 4.2L V-6. I bought replacement Motocraft SP-504 plugs from a parts store. They and their website recommended a gap of.044 for the plugs. The owner's manual and vehicle emission sticker under the hood recommend .052 - .056. The Haynes manual recommends .054.
Who's right? I'm leaning with the .054 since I have the Haynes manual, the owner's manual and vehicle emission sticker all appearing to be in agreement.
Also, I see varying opinions about anti seize compound on the plug threads and whether to torque or not. Haynes says to torque to 15 ft/lb if I remember correctly (will have to check again).
Any advice is appreciated. The work I can do. That's why I don't want to pay someone to do this. I just need to get to the right answers before I do it.
Thanks
Who's right? I'm leaning with the .054 since I have the Haynes manual, the owner's manual and vehicle emission sticker all appearing to be in agreement.
Also, I see varying opinions about anti seize compound on the plug threads and whether to torque or not. Haynes says to torque to 15 ft/lb if I remember correctly (will have to check again).
Any advice is appreciated. The work I can do. That's why I don't want to pay someone to do this. I just need to get to the right answers before I do it.
Thanks
Last edited by Ladytech; Aug 2, 2023 at 01:32 AM. Reason: Dont need the bs
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98 F150 5.4L E40D/4R100
Joined: Nov 2006
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From: MI
First off- ive been a smog tech since 1991 and have never torqued a spark plug. Run em in and tighten with your ratchet 1/4 turn past seated should do. As far as gap is concerned i go by the age of the vehicle.. if your talking a range gap of 0.52- 0.56- and the truck is new you stick to the 0.52 end of the range but as the truck gets older they usually need a bit of a bigger gap so i go more towards the 0.56 end of the range.l, so it doesnt ping on acceleration.
As far as antisieze compound is concerned- if you drive in a wet environment sometimes plugs or the threads on the head can get a lil crusty or rusty, antisieze is great for that to keep them from getting sticky and sometimes welding themselves to the hhead. i rarely use it myself on plugs because if you get that stuff on the business end of the plug it can foul out easier at least thats what i was told in auto tech training school back in 91. .
As far as antisieze compound is concerned- if you drive in a wet environment sometimes plugs or the threads on the head can get a lil crusty or rusty, antisieze is great for that to keep them from getting sticky and sometimes welding themselves to the hhead. i rarely use it myself on plugs because if you get that stuff on the business end of the plug it can foul out easier at least thats what i was told in auto tech training school back in 91. .
