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Discussion Starter · #1 ·
I had bought stock plugs for my 5.0 before I thought I was getting gt40 heads.My question is will I have any prob using these stock non gt-40 plugs in my gt-40 heads?
 

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Stock Autolite is what I use. :eyepoppin
 

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Discussion Starter · #3 ·
Great.Thats what I bought.I wasent sure since I saw gt-40 specific plugs in a magazine.
 

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'79-'84 D8OE/D9AE = ASF42C (carb) or ASF52C (CFI)
'85 E5T/AE = ASF42C (carb) or ASF52C (CFI)
'86 E6SE = AWSF42C
'87+ E7TE = ASF42C
GT-40/P = AWSF32C (motorcraft catalog) or AGSF32C (motorcraft.com)

All have the same thread size (14mm) so they're physically interchangeable between all heads. But the reach is different.

ASF = .460" reach
AWSF = .708" reach
 

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for the gt40 y and x heads you must use #agsf-32c not sure what # this is in autolite or another manufacturer. stock plugs for a 5.0 are not the same, the number of threads and how far the electrode extend into the head is different. by experience i know because i ran stock plugs for a while not knowing, plugs fouled up very easily and car noticably ran hotter. make sure you get the correct plugs
 

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There is a lot of conflicying info going around then. I'm using the AWSF 32C as that is what Summit says I should be using.???? :?:
 

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Discussion Starter · #7 ·
Yes its confusing.I am looking at the catalog from mustangs unlimited & it lists for 5.0L with GT-40 heads the motorcraft plug #AWSF42C.No other listing for GT-40 heads.Hope this helps
 

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go to fordracing.com or open up your ford motorsport catalog and it says must use agsf-32c, i dont know what the difference is with the ones your listing just make sure they are the same, you will notice a drop off in power and how your engine runs, double check that those #'s cross reference, if "awsf" is the same as "agsf" your good, the difference with the "32c" and "42c" is the heat range. the "32c" is one range colder
 
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