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440 six pack-hesitation/popping under hard acceleration

Engine Issues

  1. 440-6pack

    440-6pack Member

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    Hi dadeo,

    Yes, I’ve looked at the wiring routing at least 6 times and swapped the wires between my old ones and the new ones. I could buy another new set to be sure. Cheap assurance...

    Thank you
     
  2. Daves69

    Daves69 Well-Known Member

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    upload_2018-8-13_10-5-12.png

    The center brass float is easy. Shake it. If you hear fuel sloshing around you'll know. The nitrophyl is a bit harder. Try lowering the bowl level below the sight plug and see if stops dribbling out or it continues.
    They don't break the bank to replace...……...
    1969-71 16R-451A NITROPHYL HOLLEY 2300 FLOAT SET MOPAR SIX PACK END CARBS 2PC | eBay

    A post from a "different" car site.....
    "I worked at Holley for 4-1/2 years in the Pro-Stock carb department.
    Holley has all 3 float materials you describe, brass, which I always use, Nitryphyl, which will eventually staurate and sink, and plastic. The differences are always described as bouyancy issues for different specific grabities of street fuels, but I have never had a bad brass float in a Holley, have had issues with saturation/sinking with the Nitrophyl, and just plain uncontrollable float valve problems with the plastic ones.
    I use the brass ones, exclusively. I even change the ones in my Q-jets to brass every time I get a new one to rebuild/modify/use. "

    But to be fair, others say they never had an issue.
     
  3. dadeo1852

    dadeo1852 Well-Known Member

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    When you play with those carbs swap the rear with the front and see if the front plugs foul. You rebuilt the center, did you rebuild the end carbs too?
    The dribbling I said to look for is not from the nozzle (that's only for the accelerator pump system) but from the boosters on all 3 carbs.
    Have you tried removing all 3 sight plugs and start the car and watch the fuel level? Don't do this without rags under each.
     
  4. halifaxhop

    halifaxhop Well-Known Member

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    When checking the reluctor gap also see if the mechanical advance is free. Just see if the rotor will turn a bit almost sounds like it s frozen due to lack of maintenance (oiling during tune up).
     
  5. 440-6pack

    440-6pack Member

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    Hi Halifaxshop,

    Thank you for the tip. It is a brand new distributor. However, I did double check the mechanism functionality with a vacuum pump. Seems smooth.
     
  6. 440-6pack

    440-6pack Member

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    I just picked up a 1969 date coded six pack set up, all refurbished. This should eleiminate any fuel related concerns. I’ll be selling my 340 six pack set up if anyone is interested, i have the aluminum intake and full air filter assembly. $2750CAD obo
     
  7. halifaxhop

    halifaxhop Well-Known Member

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    Thats the vacuum advance there is also a mechanical advance easy check. The rotor should turn a few degrees in one direction only, if not the mechanical advance is not working. 99% of the time I get them in they are stuck because no one ever lubes the shaft during tune ups. That felt pad under the rotor should get a couple of drops of oil once in a while.
     
  8. Mickie Lulu

    Mickie Lulu New Member

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    STOP
    replace the the o ring on the rear carb needle and seat
    clean plugs
    set float level
    set timing 15 degrees btdc
     
  9. 440-6pack

    440-6pack Member

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    Hi Mickie,

    Thanks for the advice. Since my last post I have installed a new (used) six pack set up that I rebuilt, which included Jolley renew kits, new needles with O rings, 10.5 power valve, filters, 63 main jets. Also, new valley pan gasket. Float levels were triple checked. Spark plugs were replaced.timing was set at 5, 10, 15 and 20.

    The car runs much stronger and I left the timing at 15 and no more fouling but the engine has a pretty rough idle when it is warmed up. However, on hard acceleration it is still doing the SAME thing, it cuts out hard like as if someone was turning the key off or the coil was grounding out... i’ve Done everything as recommended from all the posts above. I’m convinced that it is now electrical wiring even though it is a completely new harness. Any additional suggestions would be very much appreciated.
     
  10. aussiemark

    aussiemark Well-Known Member

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    I was talking to a friend on the weekend and he said the repop harnesses sold by Year one are not crimped properly as in the crimp is on the insulation not the wire strands or half and half. I bought a few harnesses from Year one and will be checking them closely before fitting them. Can't remember the brand but Year one is their distributor.
     
  11. Daves69

    Daves69 Well-Known Member

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    You say "on hard acceleration" this happens. Is it possible under hard acceleration, the engine torques up and causes wiring to rub, short, or pull from?
     
  12. 440-6pack

    440-6pack Member

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    Hi AussieMark and Dave, so...I actually did come across a wire in the harness (coil) that had that exact problem. It was crimped over the wire plastic and not the copper. I fixed that issue. My next step was exactly what Dave mentioned, explore a loose connection or ground when the engine torques as it accelerates nicely when you bring the RPM’s up gradually. Thank you for you suggestions. If you think of anything else, I would appreciate any advice.