Section : Engine

Engine miss/back firing

Posted By : Gwyneth Catterall, 23-Apr-2006, 08:37pm

• Engine miss/back firing

  Posted By : Brendon Elton, 24-Apr-2006, 08:33am

  You can test your vacum advance by sucking on the pipe and using your tounge to seal the vacum, if it does not hold the vacum then the rubber inside the unit has perrished rendering the unit useless.
  
  If you have a misfire I would suggest testing and or cleaning all the following
  
  Points/Plugs/HT Leads/Ignition Timing/Coil/Rotor Arm/Distributor Cap
  
  If your engine sounds rather clicky from the top end I would suggest getting the tappets adjusted.
  
  
  Hope this helps
  Brendon

  • Engine miss/back firing

    Posted By : Steve Cureton, 24-Apr-2006, 09:04am

    If all the above are okay then your ignition timing is probably in need of adjustment.

    • Engine miss/back firing

      Posted By : Brendon Elton, 24-Apr-2006, 09:33am

      I was just wondering, Has your vehicle been converted to unleaded?
      
      
      
      Brendon

  • Engine miss/back firing

    Posted By : Gwyneth Catterall, 24-Apr-2006, 09:39am

    Thanks to Brendan for that. When I suck on the vacum pipe should I see the rod and plate inside the distributer move to advance the spark? at the moment this is not happening. I guess that if the rubber Diaphragm inside the vacum thingy is perished then I have to get a whole new unit.
    Thanks again Brendan.
    PS I had real problems with bad running some months ago, tried all the usual ignition suspects except the roter arm which looked good, no improvement till I tried a new roter arm and ...bingo ..everything was fine.
    

    • Engine miss/back firing

      Posted By : Brendon Elton, 24-Apr-2006, 10:03am

      As far as I am aware, vacum units are sealed and no moveable components are visible, try my test in the 2nd post, if it suck on the pipe and use your tounge to seal the end and it holds vacum pressure, its working. if all vacum escapes and there is no suction on your tounge the unit is faulty.
      
      
      be sure that all pipes connected to the vacum unit are flawless. no cracks splits etc. it is known that Fuel can travel down these pipes and errode the rubber diaphram inside the vacum unit, Caution, be sure not to inhale or swallow any fuel... could be dangerous to your health.
      
      
      Rgdz
      Brendon

      • Engine miss/back firing

        Posted By : Gwyneth Catterall, 24-Apr-2006, 01:32pm

        Thanks Brendon I will suck it and see!! I had thought that one would be able to observe the little rod thing in the distributor move when suction was applied? and that this rod then pulls the point plate round to advance it.
        I have ingested a fair amount of petrol over the years, usually trying to syphon the stuff, I am still here but, as you can probably tell, the brain is somewhat addled!!
        Regards

        • Engine miss/back firing

          Posted By : Gwyneth Catterall, 24-Apr-2006, 06:05pm

          Thanks all for the recent help with my missfiring triumph (dolly engine) All is now well after 'tuning' the carbs (too weak) thanks to forumite help. Then setting the ignition timing then renewing the vacum pipe (again thanks to forumite help!!.
          The vacum pipe was a bit of a puzzle... the little plastic tube was pushed so hard into the rubber 90 degree elbow that it was restricting the air flow.
          Thanks guys for the advice

      • Engine miss/back firing

        Posted By : Chris Taylor, 24-Apr-2006, 08:03pm

        Gwyneth has solved her problem, but just for the record there are TWO tests you need to do with a vacuum advance unit:
        suck on the pipe and see that there IS movement of the distributor base plate. If not, you are not getting any change in timing with vacuum changes. WHile you cannot see the diaphragm, you CAN see the movement it achieves.
        Second, suck and seal as you suggest. That will check if there is some form of leak in the system. The constant vacuum with engine running will overcome a small leak, but not a big one, but neither is of any consequence of the base plate is seized or obstructed, or the vacuum unot not actually connected!