spark plug gap

Discussion in '1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-' started by ryan218, Apr 28, 2007.

  1. quick question...what should the spark plug gap be set at for a 5.0?
  2. 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 underhood. 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.
    Illuminator likes this.
  3. I have never gapped a plug. Every one I have bought and checked was close enough for me. So I buy them and toss them in!
  4. Why does my book say 054?
    Shakerhood likes this.
  5. Yup, rite here. 87-93 = .054
    Shakerhood likes this.
  6. i gaped them at .050...runs a little better but when i go to give it gas it bogs backfires ever once in a stating to wonder if the timing is off will idle perfect for about 2 seconds then the revs will start going down and down then will either stall if you let it....or rev it and it will come back up if it dont bog...

    what should i try next to get this thing to run better?
  7. Whats your fuel pressure? Ever change your fuel filter? It could be, whats your timing at? Are the wires in order?(Firing order)
  8. Anyone else gap at 054?
  9. Didnt you say there was 7 year old gas in it? That may be the culprate
  10. LOL,, 7 year old gas? The filter is clogged!

  11. fuel pressure......hell if i know....

    fuel filter...i have a new one sitting on the work bench..where is the filter located at? is it in the tank or? idea...

  12. Its not in the tank. Its on the outside of the tank rite against the outside of it at the front part of the tank. You have to take off the cover then take off the crazy clamps. At least thats where it is in my 93.
  13. Do ALL the tune up stuff, easily knock that off the list. If the problem persists then you have a few things checked off the list. Id say new pump, filter, maybe even injectors, AFPR, new coil, wires, plugs, rotar, cap, to start. Might cost a little but a car thats been sitting NEEDS this stuff to be done! Get her running right before you ever throw a mod at it. If you start modding (Im talking any mods) before it runs right, you might never find the issue!

  14. .054 is the Gap I use as my Owners Manual says .052-.056 plus my Service Manual says the same thing and it says it again under the Hood.

  15. it wont be getting modded for a while...just the exhasut...

    so far i have done...


    what i have to install is a new fuel filter...

    btw..whats a AFPR

    Yeah...7 year old gas...i think it is...going to drop the tank sunday...

    yeah i got a new filter....just havent put it in yet!
  16. Adjustable fuel pressure regulator

    Why not pump the fuel out with a 5 dollar hand pump instead of dropping the tank?
  17. definitely start with all the tune up things first. get rid of that old gas because I assure you there is water in it. You may need a new fuel pump which in case go with a bigger puinp if you inted to mod in the future, dump some injector cleaner in the new gas, check the iac, it probably needs a cleaning at minimum and worst case scenario put a new one on. Then check the timing and set it at around 14 degrees initial. Adjust the tps to .98, and your fuel with an afpr to 39. work from there. add more fuel pressure or subtract based on how the engine runs. start wit that
  18. .054 here too.
  19. Mine are usually .054 as well but i'm gonna try a smaller gap this year.