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spark plug gap

Discussion in 'The Garage' started by Chris_T, Mar 20, 2003.

  1. Chris_T

    Chris_T 1/2 ton status

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    Did a search and found some conflicting results. I want to know about increasing the spark plug gap, specific to my truck.

    I have an intermittant miss in the truck so it's time for a tune up, including changing the plugs. I'm currently running AC R45TS (I believe). I know that the recommended gap is .045, but I've heard recommendations both for and against increasing the spark plug gap. The heat range seems fine, so I'll stick with the same plug.

    The engine is a mild 350, flat tops and 882 heads. The ignition consists of a Crane Cams optical ignition points replacement, an MSD Blaster 2 coil, MSD cap and rotor and Taylor spiral-pro wires. Should I run .045" or increase the gap, and if so, how much?
     
  2. Hossbaby50

    Hossbaby50 3/4 ton status

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    With my carb dialed in and my MSD igntion I ran .057 in Phoenix. Now I am in Colorado, and my carb is running rich. So I have backed my gap off to .050. If you have a decent igntion system then I would say open it up to about .052 and see what you think.
     
  3. Lonnie

    Lonnie 1/2 ton status

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    Since you do not state having a MSD6A or equivalent ignition box, I would stay around .045. There is little power to be gained in increasing gap on a low compression street engne. A larger gap will also add stress to the rest of the ignition & increase chance of misfire. As many have experienced rotor burn through on electronic ignitions (not applicable to remote mounted coils), this can aggravate this situation due to the magnetic field produced from the coil above the rotor. The electricity is seeking a ground & will take the easiest path.... sometimes not to the plug.
     
  4. Don

    Don 1/2 ton status

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    O.E.M Chevy with an HEI ran with .065 as a gap. try that. /forums/images/graemlins/shocked.gif
     
  5. schmuck

    schmuck 1/2 ton status

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    open it a little and try it , you will not see a gain in hp or milage even though you might it will be minimal, then open it up some more,
     
  6. Chris_T

    Chris_T 1/2 ton status

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    I take it that a smaller gap is more forgiving of the air/fuel mix?
     
  7. BowtieGuy3

    BowtieGuy3 Guest

    Opening the gap on the plugs just makes the secondary ignition come to a higher voltage charge before discharging. I never really noticed any performance gains from increasing the gap, but it can help if you go through the tedious task of fine tuning everything in the ign. system to eak out some...
     

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