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Spark Gap!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Heavymetal, Nov 17, 2001.

  1. Heavymetal

    Heavymetal 1/2 ton status Premium Member

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    I need a little help. Today I put a Accel super coil on my HEI. At the same time I put in a new set of AC Delco plugs, R44T. I removed a set NKG's. I had read somewhere on this board that when putting a high output coil on the HEI, you should increase the spark plug gap to .060. Thus I did this. Now I was not expecting a dramatic increase in performance, but I sure did not expect to lose any either. Well I did, now it seems a little sluggish. Did I gap it to far? By the way the cap and rotor are brand new, and it already had 8mm Accel wires on it with only a few thousand miles on them. Any suggestions?

    Thanks,
    Mike.

    77'/87' 3/4 ton Burb, 400cu, sm465, np205, 14boltff, dana44, 4.10s, 35in BFG's.
     
  2. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Accel is known to do goofy things. Never heard a single gripe or moan about MSD. Install like they say and go back to the parts store. If they don't believe you, take 'em for a ride. Then change your stock stuff back and go for another ride with them. There is no excuse for selling stuff that decreases peformance and charge big bucks for them.

    We had a post a while back about MSD. Everyone that put in the MSD box loved it. There was a dramatic performace increase. Even with just MSD wires I noticed more guts. A box, wire, and coil from MSD should make a noticible kick in the pants for ya.

    "I ain't nobody, dork."
    <a target="_blank" href=http://www.geocities.com/bigkern76>http://www.geocities.com/bigkern76</a>
     
  3. high&liftedup

    high&liftedup Registered Member

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    I believe .60 is a bit much... try going in increments of .005 starting at .40-.45.

    I had a accel super coil and worked well until I install all MSD

    HE will always get you out of the mire clay!!!
     
  4. Heavymetal

    Heavymetal 1/2 ton status Premium Member

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    Stock is .045. You say that your Accel worked fine until you installed a MSD. Does that mean that when you installed the MSD that you noticed an increase in performance over the Accel? Also do you have an HEI. Between the change over, did you use the same plugs? What was the gap you used?

    Thanks,
    Mike.

    77'/87' 3/4 ton Burb, 400cu, sm465, np205, 14boltff, dana44, 4.10s, 35in BFG's.
     
  5. high&liftedup

    high&liftedup Registered Member

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    Mike.. I used a accel (hei) for years on my 76, then I had module probs. I went to a Accel dist and decided later to install a MSD off road box... Great mod... but 3 months later I had some issues. After replacing everything electronic, including sending the box back to MSD as I had suspected, it MAY have turned out I was having secondary "cross talk" to the magnetic coil wires...The plugs I am using are autolights at .045... I need to replace them... got any suggestions???

    Thanks....

    HE will always get you out of the mire clay!!!
     
  6. Heavymetal

    Heavymetal 1/2 ton status Premium Member

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    I think tommarrow I will reduce the gap to.050, and see how that works out. I hate to do it, getting those plugs in and out is a real pain. I broke one in two today, and had to drive to two stores to get a new one. Thanks for the input.

    Mike.

    77'/87' 3/4 ton Burb, 400cu, sm465, np205, 14boltff, dana44, 4.10s, 35in BFG's.
     
  7. Thunder

    Thunder 3/4 ton status

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    Increasing the gap on the plugs wont give you all that much of a performance increase. It might increase your gas milage a bit though.
    if you want to do something to your plugs to increase performance, Side gap them.
    Side gapping is grinding off the electrode arm so the center electrode is exposed then gapping the plug from the side of the center electrode to the arm. This exposes the whole spark to the air fuel mixture. It will give a very nice increase in preformance and gas milage that is very noticible.
    The main drawback to doing this is that the plugs wear out faster because the spark is always coming off the same small area of the electrode and need to be regapped every now and then. But if your plugs are a PITA to get in and out it may not be worth it.

    <a target="_blank" href=http://coloradok5.com/gallery/Thunders-Blaze>http://coloradok5.com/gallery/Thunders-Blaze</a>
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  8. Heavymetal

    Heavymetal 1/2 ton status Premium Member

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    Side gapping is a very interesting idea. I may give that a try. The reason it's so hard is because of my headers. I'm also considering putting my NKG's back in gapped at .050. Anybody else have any thoughts on this?

    Thanks,
    Mike.

    77'/87' 3/4 ton Burb, 400cu, sm465, np205, 14boltff, dana44, 4.10s, 35in BFG's.
     
  9. 76chevy

    76chevy 1/2 ton status

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    Did you accidently move your timing? I'd double check it.

    Are you sure you got the right plugs? You can also run a R45T plug based upon your emmisons designation.

    I think the .060 gap is only if you install the MSD ingintion box, not just the Coil or module.

    <font color=red>Spirit of 76</font color=red>
     
  10. Heavymetal

    Heavymetal 1/2 ton status Premium Member

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    No, I didn't accidently move the timing. I did, however, adjust it after the fact. That helped a little, but still not as good as before adding the new plugs and coil. I agree, I think that the problem is just the gap.

    Mike.

    77'/87' 3/4 ton Burb, 400cu, sm465, np205, 14boltff, dana44, 4.10s, 35in BFG's.
     
  11. 502Burban

    502Burban 1/2 ton status

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    I have to agree with 76Chevy; going to a .060 gap should only be done with a high energy box like MSD (or others). I don't think that adding the hotter coil by itself would allow you to run that large a gap.

    You are probably on the right track with re-gapping to .045 - .050 range. Or, you could save the knuckle-busting and leave the gap and add a MSD box. [​IMG]

    Robb
    '73 GMC Suburban - 502DFI
    <a target="_blank" href=http://community.webshots.com/user/robbrj>community.webshots.com/user/robbrj</a>
     
  12. sosamantx

    sosamantx 1/2 ton status

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    I'd go back to .045 gap!! I have the MSD 6A on my Nova and they suggested that I might open up the gap to .060, but I still gap it at .045. you can try experimenting with the gap(s) and all, but i'ts just another something you'll have to remember.

    <font color=blue>Steve Sosa a.k.a. "sosaman"</font color=blue>
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  13. shawnboy

    shawnboy 1/2 ton status

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    Hey Mike, gap your plugs at 45 thou and since you have headers make sure the plug boots click into place and check to see if you've got any spark leakage cause wire life can be shortened due to contact with the headers. If all else fails switch to MSD and gap to 55 thou.and stick with AC Delco plugs.
    Shawnboy.

    <font color=red>If you are having too much fun it's probably illegal.</font color=red>
     
  14. JunkYardCrawler

    JunkYardCrawler 1/2 ton status

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    i had an msd 6a box and a msd coil on my old step side. untill my distributor blew up.
     
  15. Heavymetal

    Heavymetal 1/2 ton status Premium Member

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    Well I re-gapped my plugs to .050 and my truck seems be be running about the same as before I started all this. It's times like these that make me want to go out and buy a newer turbo-diesel burb. All that time and money wasted. Oh well, live and learn I guess. Thanks for all the input.

    Mike.

    77'/87' 3/4 ton Burb, 400cu, sm465, np205, 14boltff, dana44, 4.10s, 35in BFG's.
     
  16. Hossbaby50

    Hossbaby50 3/4 ton status

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    .060 is recommended when you have an MSD box, coil, and wires. I run .057 with this setup. .060 is too high for just a coil without a box.

    My Chevy isn't broken, its just out of gas.
     
  17. dyeager535

    dyeager535 1 ton status Premium Member

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    GM ran .060 in Oldsmobiles for a long darn time. Same system. You can run .060 gap with HEI, it will jump near a 1/2" gap anyways. Of course varaibles such as compression and chamber design are going to make a difference, but HEI has NO problem jumping a .060 gap in good conditions.

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     

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