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Subject: stumbling 8n

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Jakester    Posted 07-25-2018 at 11:33:16 [URL] [DELETE]        [Reply] [No Email]  
  • stumbling 8n
  • '48 8n front mount, 12 volt, 12 volt coil, original ballast resistor. Has never started good but now won't go without a lot of trying. Good spark (new Echlin points and condenser), new solid core wires. When it runs, it won't rev or take any load without backfiring and missing. No power! Had to replace the distributer a couple years ago because original was cracked. Got it started today by taking out a sparkplug and grounding it to engine. Would run on 3 cylinders. I can hold sparkplug n frame while it cranks but get lifted when it starts. What's going on?

    K.LaRue-VA    Posted 07-26-2018 at 09:43:37 [URL] [DELETE]        [Reply] [No Email]  
  • Re: stumbling 8n
  • How long has it been since wire terminals were cleaned? This is not as much of a problem with a 12 volt system, but can still eventually become a problem. This is especially true while cranking. Available battery voltage is lower while cranking. Both ends of both battery cables clean and shiny. Make all terminals in the ignition circuit clean and shiny. Replace the ignition switch.

    When replacing the distributor, was the timing set right? I've got two distributors that I had to file the screw slot in the housing longer, so the plate would move far enough to set the timing. Once the timing is right, the special brass screw that makes contact with the coiled springy terminal is now offset to one side. I have to bend the coiled springy terminal to that side.

    Slow to start may also be caused by poor compression. The older the engine gets, the longer it seems to take to get cylinders to fire. Using more choke may help with that, but a rebuild is not far off. Removing a spark plug removes the compression load of one cylinder. Faster cranking equals higher compression, making the other cylinders easier to start.

    When was the air filter last completely cleaned out? I've seen those so clogged the engine shouldn't have been able to get enough air thru them.

    Jakester    Posted 07-26-2018 at 11:29:49 [URL] [DELETE]        [Reply] [No Email]  
  • Re: stumbling 8n

  • Thanks, I did have a problem this spring with a bad ground connection. I have checked and rechecked the points gap and the timing. Both are set as to manual specs. Its not an old engine, I rebuilt about 10 yrs ago and compression is good.

    Jakester    Posted 07-26-2018 at 09:29:05 [URL] [DELETE]        [Reply] [No Email]  
  • Re: stumbling 8n
  • My question is should I be able to hold on to a grounded sparkplug with my bare hand and not get shocked while engine is cranking? I get shocked after the engine starts. Could something be grounded out causing my stumbling problems? Thanks!!

    steveVa    Posted 07-25-2018 at 13:29:58 [URL] [DELETE]        [Reply] [No Email]  
  • Re: stumbling 8n
  • I would say. Clean / adjust points. Clean/adjust carb. If that fails I would bypass resistor or replace resistor. But wait for others to chime in on bypassing the resistor. I would hate to cause you to burn something up...

    steveVa    Posted 07-26-2018 at 12:39:05 [URL] [DELETE]        [Reply] [No Email]  
  • Re: stumbling 8n
  • To me that leaves bypass the key switch, and or try another coil.

    jakester    Posted 07-25-2018 at 19:05:19 [URL] [DELETE]        [Reply] [No Email]  
  • Re: stumbling 8n
  • Thanks, have done all that. Might add that have a good stream of gas through the carb.

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