I have a miss

Mopar Racers Forum

  1. twayne24365

    twayne24365 Well-Known Member

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    So when driving and holding rpms at around 3000 in any gear there is a noticable miss, as if its cutting out
    .30 over 440
    10.6:1
    Cnc stealth heads
    .620 .626 258* 260* @50 hughes solid cam
    Victor with 850 holley
    1 3/4 headers
    440 source pro billit distributor
    Msd 6al and msd 8.5mm super conductor wires
    New plugs

    FUEL
    Holley blue pump up to an aeromotive regulator all -6 line and pressure at 7psi
     
  2. 68gtxman

    68gtxman I used to reMember

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    Electrical problem somewhere would my guess. A better description of the actual symptoms would help more.
     
  3. sst3193

    sst3193 Well-Known Member

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    Consider putting 2 inch headers on that beast, then figure out if it's spark or fuel. My vote is on reversion with that combo. Plugs are taking a beating, Maybe?
    Good luck, sounds like a nice engine!
     
  4. 69B-Cuda

    69B-Cuda Well-Known Member

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    try a different coil? I had one that only had a miss at a certain RPM... swapped the coil out and it went away....
     
  5. twayne24365

    twayne24365 Well-Known Member

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    To describe what it does more, is like i said when driving steady at 3000 rpm it has a miss, like it cuts out then comes back in, each time it does it it drops about 100-200 rpms, above 3000 its smooth as could be with no miss at all....
    I know the big cam and intake with a 4800 coverter and 456 gears is the cause of the raspiness and roughness from idle till about 2500, but i deffinately think the miss at 3000 is ignition related, just not sure where to start.
     
  6. twayne24365

    twayne24365 Well-Known Member

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    And here is a plug
     

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  7. twayne24365

    twayne24365 Well-Known Member

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    Could be the cause, that blaster has been in use since the 90s and was used with 3 different motors when dad had his 71 challenger
     
  8. OldmanRick

    OldmanRick Well-Known Member

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    I agree, sounds like a ignition problem? But is this something new? What I'm getting at is, did it run fine before with your current setup and then just start happening? The plug looks like it has some color from what I can see, but is there any chance the engine is going lean at 3k with a light load? I'm sure the timing is all in by then, so what "total" are you running?
     
  9. twayne24365

    twayne24365 Well-Known Member

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    Well its been pestering it the whole time, and during break in we had 5 gallons of cam 2 and 5 gallons of 93 to be safe, and it was deffinately lean, blue flame shooting out of the headers bout 3' long. So we went from 80 jets squared to 84s and that seemed to eliminate that. And timing is right at 36* total
     
  10. 340doc

    340doc Well-Known Member

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    Also check pickup to reluctor gap in dist. .008 with a brass feeler gauge. Just a thought.
     
  11. bOb shingler

    bOb shingler Well-Known Member

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    in the pic the timing looks perfect. the plug looks way over rich to me and it has a lot of oil on it. so I'd look at the intake gaskets and valve stem seals to be the oil problem first. reseal your motor then replace the coil and msd6al and install new plugs.
     
  12. twayne24365

    twayne24365 Well-Known Member

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    Intake gasket seems to be fine, and heads were redone with new springs, seals and valve job right befor i put it together, could it be a lean burn at that rpm, maybe a powervalve?, ill eliminate the possibility of the coil, a buddy of mine has a brand new one we can throw on it.
     
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