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1987 - 1996 F150 & Larger F-Series Trucks 1987 - 1996 Ford F-150, F-250, F-350 and larger pickups - including the 1997 heavy-duty F250/F350+ trucks

Spark Plug Gap

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Old Mar 7, 2012 | 07:29 AM
  #1  
Kaizer88's Avatar
Kaizer88
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From: Lake Butler Fl
Spark Plug Gap

Got another one for yall. I changed my spark plugs not to long ago and gapped them at .044 and yesterday i changed them to .054 and now it seems like i dont have the power i did at .044. I have a 1989 302 is there anything bad that could happen with running the plugs at .044. This weekend I also plan on bumping the timing up to 14 BTDC as well
 
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Old Mar 7, 2012 | 08:21 AM
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It takes more "punch" from the coil to jump the extra gap. If your coil is weak due to age or other factors then increasing the plug gap may not work to the desired result. What you are trying to accomplish is referred to as the "sixlitre tuneup". Increased gap, bumped up timing and the last part is good quality plug wires/cap/rotor and a hotter coil.

If you want to run with the increased plug gap you may as well pony up for a new coil, wires, cap&rotor.
 
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Old Mar 7, 2012 | 09:17 AM
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^+1 what he said!
just did the new cap & rotor, wires, plugs, and coil (all MSD except Motorcraft plugs gapped to .055) and bumped timing 13.5* and my butt dyno felt the positive results! spend the extra money and make it truly worth the time and effort
 
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Old Mar 7, 2012 | 10:13 AM
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how can i tell if my coil is weak? will this increase MPG by doing a 6 litre tuneup? man rla you are on top of your game you have answers to all questions...
 

Last edited by Kaizer88; Mar 7, 2012 at 10:15 AM. Reason: needed to add something
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Old Mar 7, 2012 | 01:53 PM
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Originally Posted by Kaizer88
how can i tell if my coil is weak? will this increase MPG by doing a 6 litre tuneup? man rla you are on top of your game you have answers to all questions...
You may have already answered that question. You opened up the plug gap and now you state you felt like the performance decreased. This could also be caused by cheap or faulty plug wires as well. By opening up the gap it is taking more "oomph" to jump the gap.

You could pull a plug, ground the electrode, crank the engine over then observe the spark. It should be a nice "fat" bluish-white color. If not start suspecting a less than stellar coil, but also keep in mind the plug wires can also be at fault.

It's matter of process of elimination unless you have a high voltage probe and oscilloscope to measure the voltage.

Many on this forum, and Fullsize Bronco where sixlitre haunts, have benefited from the timing/plug gap bump in power and some MPGs.
 
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Old Mar 7, 2012 | 02:11 PM
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i know it aint the plug wires. i have msd plug wires
 
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