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6 Posts
Discussion Starter · #1 ·
So looking here

It shows that the correct gap for my car (completely stock) is .054

So that's what I set the gap to... BUT... then I realized the plug I was using is NOT the "ASF-42" since you pretty much can't find that plug anymore.

The one I installed was "ASF-42CA."

So I'm wondering if the gap is too large on the plug since it's not the same plug?

Or is .054 correct?

Car seems to be running correctly, but the gap on the plugs I pulled out was more like .045 or something (the dealer did the plugs last not me).

Thanks for any help!

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4,144 Posts
Ford Suggests .052--.056

autolite 24's
gap (factory setting) .054

From "The Official Ford Mustang 5.0 Technical Reference & Performance Handbook 1979-1993" Ford Racing Part No. M-1832-Z4
Page 274
"Spark Plug Applications" table
Year---------Engine--------------Motorcraft number-------Gap (inches
1979---------5.0L (49 state)-------ASF-52-------------------.050
1979---------5.0L (California)------ASF-52-6----------------.060
1980---------4.2L (all)-------------ASF-42-------------------.050
1981---------4.2L (all)-------------ASF-52-------------------.050
1982---------4.2L (all)-------------ASF-52-------------------.050
1982-1985---5.0L carbureted-----ASF-42-------------------.044
1982-1985---5.0L CFI-------------ASF-52-------------------.050
1986--------5.0L H.O.-------------ASF-34 or 44-------------.050
1987-1993---5.0L H.O.-----------ASF-42-------------------.044
1993--------5.0L GT-40 (Cobra)--AWSF-42C---------------.050

1. Factory electrode gap specifications are shown on each Mustang's VECI label that is affixed under hood. The relatively wide gaps specified created the fat, long-duration spark needed to ignite the lean mixtures prescribed for most normal operating conditions.

2. Most non-Cobra 5-liter motors typically run well with spark plugs gapped at .052 inch. For normally aspirated engines in high-performance service, a plug gap between .040-.045 inch is suggested by many tuners. Those same sources also suggest .028-.034 inch in turbocharged, supercharged, and nitrous-fed five-ohs.

3. Some 1993 GT-40 Cobra motors were factory fitted with colder, AWSF-32C spark plugs.

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2,802 Posts
E6SE heads require AWSF plugs, not ASF

W = 0.708" reach
Non-W = 0.460" reach

E6SE heads were used in all High Output and Standard Output 5.0L Ford/Lincoln/Mercury engines in model year 1986 and all S.O. 5.0L F/L/M engines in model years 1987+

1979-93 Capri and Mustang 5.0L heads...
1979-84 D8OE/D9AE heads = ASF42C or 52C (CFI)
1985 E5AE = ASF42C or 52C (CFI)
1986 E6SE = AWSF42C
1987+ E7TE = ASF42C
1993 F1ZE/F3ZE (GT-40) = AWSF32C
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