350 misfire and stalling

Discussion in 'Engine Topic' started by matt-81z28, Sep 4, 2020.

  1. matt-81z28

    matt-81z28 New Member

    Messages:
    7
    Likes Received:
    1
    Joined:
    Aug 11, 2020
    Hey guys, so I have been working on getting my 81 z28 into drive-able condition, car has been driven it seems like it’s whole life, was a daily driver from the guy I bought it from. Car has had the original 350 and quadrojet taken out and had a Chevy crate 350 HO motor put in around 2002 with a quadrojet off a 79 z. Car has been semi driveable but seems like it has gotten worse even with more parts going in. Now it will fire up and idle smooth for a few minutes and once the engine gets warm the car will stall out, even with the throttle pushed in. After it dies if you try and start it up it will start misfiring and occasionally backfire. I have put new spark plugs, accel 8.5 wires, bwd coil and cap(just to test). The car only seems to run bad with heat increasing so I’m assuming it has something to do with ignition. Any ideas would be much appreciated. Thanks guys
     
  2. biker

    biker Veteran Member

    Messages:
    2,159
    Likes Received:
    777
    Joined:
    Dec 7, 2014
    Location:
    Canada
    If the HEI distributor is original, they have issues with the pickup coil wires breaking because the move a bit every time the timing plate moves. You can replace the pickup coil, distributor has to come out, gear off, shaft out, change pickup and reassemble. Way easier to just get another good HEI. Even decent ones are not expensive now.

    If the distributor IS original, there is lots more worn out in there too. Replace it!
     
  3. matt-81z28

    matt-81z28 New Member

    Messages:
    7
    Likes Received:
    1
    Joined:
    Aug 11, 2020
    Not sure if distributor is original, cap, coil, and rotor were accel. I will look at the rest of distributor to be sure, might as well replace it anyway. Wiring does not look too good. Thanks for your help
     
  4. RS1979

    RS1979 Veteran Member Lifetime Gold Member

    Messages:
    3,970
    Likes Received:
    912
    Joined:
    Jun 18, 2013
    Location:
    Memphis, TN
    When the HEI distributor control module is going bad, it will fail when it gets hot. After sitting for awhile, it will cool off and the car will start. It's been a long time since I've had that problem so I can't remember if mine ever backfired.
     
  5. biker

    biker Veteran Member

    Messages:
    2,159
    Likes Received:
    777
    Joined:
    Dec 7, 2014
    Location:
    Canada
    I've been lucky with factory modules, but I have heard they do fail occasionally. Coil can poop the bed from heat too. Lots of reasons to pop for a whole new distributor.
    So you have eliminated any carb issues? Fuel pressure, choke, vacuum leaks? Sure sounds like ignition, but nice to narrow it down with diagnosis before throwing parts at it.
     
  6. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

    Messages:
    28,285
    Likes Received:
    1,678
    Joined:
    Feb 26, 2004
    Location:
    Bloomington, MN
    You can get a complete billet aluminum distributor on ebay for less that the cost of a module and coil at your local parts store.
    I've had one of them for several years now with no problems.

    That's probably a part worth throwing at the problem.
     
    cadillac_al likes this.
  7. biker

    biker Veteran Member

    Messages:
    2,159
    Likes Received:
    777
    Joined:
    Dec 7, 2014
    Location:
    Canada
    Agreed. Especially given all the other worn stuff that's likely in the old one.
     

Share This Page