Very odd ignition problem and spark plug wire resistance values....

Discussion in 'Troubleshooting & Diagnosis' started by 70SSRS350, Jul 8, 2021.

  1. MChamp

    MChamp Veteran Member

    Messages:
    406
    Likes Received:
    111
    Joined:
    Jun 6, 2021
    Location:
    north carolina
    My bad, I haven't seen where he tested the actual voltage at the plug wire end. Timing light is the only way I know how.
     
  2. 8pack

    8pack Veteran Member Lifetime Gold Member

    Messages:
    2,964
    Likes Received:
    313
    Joined:
    Aug 29, 2007
    Location:
    Western, MA
    You really need to set up a checklist at this point and go back over everything in a very methodical way.
    At this point chasing different potential problems as they seem to pop up isn’t getting you anywhere. Once you are 100% sure your install is bulletproof then there aren’t too many places to go except the carb, which could definitely be the issue or something internal which sounds unlikely. But you need to rule everything else out first.

    Timing- what’s your initial timing and advance? Check it again and verify.

    Firing order- Check this first and even if you checked it before check it again. When I was setting up my engine I thought I was sure I had it right but it turned out I had 2 wires crossed even though I had checked it twice.

    Where is your vacuum advance hooked to on the carb. Is it in the correct connection.

    Are there any open vacuum ports in the carb that need to be capped

    Where are you getting your vacuum for your power brakes.

    is your carb evenly tightened Doern and not over tightened or loose.

    Is the gasket between the carb and the intake in good shape.

    Are you using a carb spacer. Is it properly installed.

    Verify your fuel filter is good. If you don’t have a clear one where you can see the filter just change the old one out. Make sure the filter is facing correctly and fuel is flowing through it in the right direction.

    Does your carb have its own fuel filter? Verify that is installed correctly and clean.

    If you have a pressure gauge verify your are getting fuel to the carb at the right pressure. If you dont, disconnect the fuel line and run it to a jar or bucket and crank the engine over with the coil disconnected so it doesn’t fire and verify your fuel pump is working. If the engine is running at all the pump is probably good but check the boxes.

    You are running a pertronix electronic ignition instead of pouts it looks like? Make sure that is installed properly. I don’t know how to test it to verify it is working but you could reinstall the points and see if that fixes it.

    Check your grounds….battery to engine, Engine to frame etc. Engine to body. A bad ground can do crazy things. Coil ground, distributor ground.

    Check positive connections as well at the starter and battery.

    Is the distributor tight.

    Check all the manifold bolts and Re-torque them in order.

    Although some of these things may not seem relevant, going back over your install in detail and verifying everything may lead you to the problem in an unexpected place.

    There is probably more to check but that will get you started.
    C183D986-8DE8-4482-A83F-A48CC9F86B5B.png
     
    70SSRS350 likes this.
  3. 70SSRS350

    70SSRS350 Veteran Member

    Messages:
    432
    Likes Received:
    3
    Joined:
    Jul 30, 2010
    Location:
    ITALY
    Sorry for confusion, but the diagram picture I posted is not firing voltage but it's compression test (with European pressure units, Bar or ATM)....
     
  4. 70SSRS350

    70SSRS350 Veteran Member

    Messages:
    432
    Likes Received:
    3
    Joined:
    Jul 30, 2010
    Location:
    ITALY
    Yes, of course, I've got a timing light and I've already checked the spark of each wire plug.
    I've already replaced distributor cap, rotor, 3 coils, wires and spark plugs: no difference.

    About the Pertronix Ignitor 2, I've already removed it and put back points (with proprer coil) but nothing changed, so now I reinstalled the Pertronix.
     
  5. 70SSRS350

    70SSRS350 Veteran Member

    Messages:
    432
    Likes Received:
    3
    Joined:
    Jul 30, 2010
    Location:
    ITALY
    End of the story.... after 2 months checking, testing and replacing ignition parts with no improvements, today I found the issue in.... the carburator.
    As I wrote yesterday, cylinders of one plenum of my dual plane intake were not working.
    And, in fact, there was a very small piece of dirt (maybe sealant?) inside one of the primary jets.
    The carburator has been already cleaned but this little bastard didn't go away....
    Once cleaned and reassembled the carb, now the engine is running like a swiss clock...
    You can only image how many Italian bad words I spoke!
     

    Attached Files:

    MChamp and cadillac_al like this.
  6. Dave Nelson

    Dave Nelson Veteran Member

    Messages:
    5,516
    Likes Received:
    5,181
    Joined:
    Dec 19, 2003
    Location:
    Vineland N.J USA
    Glad you found the problem, actually that's a fairly large piece of dirt for inside any carburetor. LOL
     
    70SSRS350 likes this.
  7. 8pack

    8pack Veteran Member Lifetime Gold Member

    Messages:
    2,964
    Likes Received:
    313
    Joined:
    Aug 29, 2007
    Location:
    Western, MA
    Congrats! Fuel……..
     
    70SSRS350 likes this.
  8. 70SSRS350

    70SSRS350 Veteran Member

    Messages:
    432
    Likes Received:
    3
    Joined:
    Jul 30, 2010
    Location:
    ITALY
    Yes, that was the real problem, the carb was very clean (beside this small debris) and looked fine. So it was impossible to think about dirt in the carb...
     
  9. Patstuff28

    Patstuff28 Veteran Member

    Messages:
    444
    Likes Received:
    855
    Joined:
    Aug 23, 2020
    It’s always a plus to be able to swear in more than one language. Good job fixing the problem!
     
    70SSRS350 likes this.
  10. mallard

    mallard Veteran Member

    Messages:
    1,464
    Likes Received:
    457
    Joined:
    Oct 3, 2013
    Location:
    SK, Canada
    What prompted you to check inside the jets? (Easy to overlook)
     

Share This Page