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Technical 1970 GMC 292 no spark

Discussion in 'The Hokey Ass Message Board' started by Zackalackin, May 9, 2019.

  1. Zackalackin
    Joined: May 9, 2019
    Posts: 10

    Zackalackin

    hello all,

    I have an old K10 with a 292 inline-6 that has been dead reliable every time I start it- until last weekend. I drove it up to the mountains (6500ft) and back down to the town I live in (5300ft). The truck was running for about two hours non stop.

    On the very last leg of the trip, I was coasting down hill in 4th gear, and noticed the exhaust “burbles” getting a little louder, I pressed in the clutch, and a huge explosion sounded, later found out to be my muffler exploding. After this, the truck stumbled pretty heavily, and would die out if I touched the gas pedal. Spark finally gave out and died and I restarted it, but then the power would get weaker and weaker, as I stumbled down the road, then finally died for good and wouldn’t restart, battery was holding good voltage and turning her over just fine.

    On the side of the road, I replaced the points, gapped to .018” replaced the rotor, cap, plugs, wires and coil all to no avail. Towed her home and replaced the starter, starter solenoid, and tried three more coils, and replaced the all wiring from the ignition to the starter and battery etc. truck just isn’t putting spark to the coil, not even if I jump power straight the coil from the battery.

    I’m at my wits end and need some help getting this old girl running again!!
     

    Attached Files:

  2. Doublepumper
    Joined: Jun 26, 2016
    Posts: 1,534

    Doublepumper
    Member
    from WA-OR, USA

    Condenser replaced?
     
  3. is the rotor turning when it is cranking? did you check the little wire inside the distributor?
     
    squirrel likes this.
  4. Zackalackin
    Joined: May 9, 2019
    Posts: 10

    Zackalackin

    I replaced the condenser attached to the coil, as well as the condenser inside the distributor. @tb33anda3rd, The rotor is spinning when cranking, and points seem to be opening and closing as they should. I haven’t messed with the timing, because it was running when it died.
     

  5. Doublepumper
    Joined: Jun 26, 2016
    Posts: 1,534

    Doublepumper
    Member
    from WA-OR, USA

    Grab the rotor and see if it will turn. Pin may have sheared on the dist. drive gear.
     
  6. sdluck
    Joined: Sep 19, 2006
    Posts: 3,185

    sdluck
    Member

    the condenser on the coil is a radio suppressor not a condenser and has a different MF rating
     
  7. squirrel
    Joined: Sep 23, 2004
    Posts: 55,931

    squirrel
    Member

    check timing. If it has a fiber cam gear, that could have stripped, too.
     
  8. sdluck
    Joined: Sep 19, 2006
    Posts: 3,185

    sdluck
    Member

    do you have a volt meter
     
  9. Zackalackin
    Joined: May 9, 2019
    Posts: 10

    Zackalackin

    The rotor has a little bit of play in it and is sparking when I wiggle it.
     
  10. Zackalackin
    Joined: May 9, 2019
    Posts: 10

    Zackalackin

    I haven’t pulled the distributor but I checked via the spark plug hole that I am timed at 0BTDC
     
  11. Zackalackin
    Joined: May 9, 2019
    Posts: 10

    Zackalackin

    I don’t have one but I’m thinking I need to get one
     
  12. Doublepumper
    Joined: Jun 26, 2016
    Posts: 1,534

    Doublepumper
    Member
    from WA-OR, USA

    Pull #1 plug and bump starter to get it up on comp. stroke, align timing marks on damper and check to see if the rotor is pointing at #1 post on dist. cap.
     
    Zackalackin likes this.
  13. Zackalackin
    Joined: May 9, 2019
    Posts: 10

    Zackalackin

    image.jpg image.jpg Ok I think the timing marks are aligned. Dist is definitely not pointing to number 1.
     
  14. Doublepumper
    Joined: Jun 26, 2016
    Posts: 1,534

    Doublepumper
    Member
    from WA-OR, USA

    Pull the dist. and see whats up. Fairly common to have them shear the drive pin.
     
    XXL__ likes this.
  15. Zackalackin
    Joined: May 9, 2019
    Posts: 10

    Zackalackin

    When the rotor is pointed at cylinder #1 the timing mark on the tamper centered inline with the motor/valve cover, well above that “A” mark on the timing tag
     
  16. Zackalackin
    Joined: May 9, 2019
    Posts: 10

    Zackalackin

    I’ve never re-timed an engine from scratch so I’ll need a little handholding from that end. Pulled the dist, what exactly am I looking for here? Thanks
     

    Attached Files:

  17. Zackalackin
    Joined: May 9, 2019
    Posts: 10

    Zackalackin

    If the drive pin is sheared can that be replaced or do I need a new distributor? I’ve never had an issue with points, would it be worth looking at the conversion to HEI at this point?
     
  18. you can put a new pin in and there is no reason to change to HEI.
     
  19. Sounds like condenser isnt holding the charge. Replace condenser, should be good to go.
     
  20. Doublepumper
    Joined: Jun 26, 2016
    Posts: 1,534

    Doublepumper
    Member
    from WA-OR, USA

    Clean it up, verify the condition of the pin and that the gear is firmly attached to the shaft and hasn't slipped. The pin can be replaced. Points are fine...no need for HEI.
     
  21. Zackalackin
    Joined: May 9, 2019
    Posts: 10

    Zackalackin

    I’m not sure what the pin is supposed to feel/look like but the gear at the end of the dist has about 1/4 of slop up and down
     
  22. Doublepumper
    Joined: Jun 26, 2016
    Posts: 1,534

    Doublepumper
    Member
    from WA-OR, USA

    It's just a roll pin. Sounds like you found the problem. The gear should not move on the shaft.
     
    Zackalackin and XXL__ like this.

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