Knock Knock... Who's there? Cylinder #3!

Discussion in 'Ranchero Tech Help' started by FordR500GT, May 29, 2018.

  1. FordR500GT

    FordR500GT In Maximum Overdrive BRONZE MEMBER

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    As I mentioned before, my '72 500 wa running like crap. Found problem #1... There was a vacuum leak behind the carb, so it now runs without mixture screws backed out all the way. After I fixed the loud hissing(vacuum leak), I could hear a ridiculously loud lifter tap. (technically not a knock, but you get the point).
    Yesterday, I decided to investigate the issue. When I pulled off the valve cover, it was quite apparent which rocker was making the noise. I pulled off the rocker, amd removed the pushrod. The pushrod was bent to hell.
    Luckily, Roy had given me some spare ones.. Go figure. After buttoning everything up, it runs a helluva lot better, but I'm still having an issue. It now has an actual throttle response, but still coughs under acceleration. If you step on it, it stumbles very violently, but after a second, it picks itself up and spins the tires. Timing is set, no vacuum leaks, carb is rebuilt, nd fuel lines are clear... Confused :confused:
     
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  2. ForistellFord

    ForistellFord In Maximum Overdrive GOLD MEMBER

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    Good old Roy!!!!!!! He should post more.
     
  3. Jeff B

    Jeff B In Maximum Overdrive BRONZE MEMBER

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    Are you getting a good shot from the accelerator pump? With the engine off, remove the air cleaner lid and with the choke open, look into the carby and work the throttle linkage. You should see a solid squirt of fuel going down the
    primary barrels.
     
  4. CJ Guy

    CJ Guy In Maximum Overdrive

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    Very busy, bought a house back in Ar and moving a shit load of stuff and cars, maybe when I can actually retire.
     
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  5. ForistellFord

    ForistellFord In Maximum Overdrive GOLD MEMBER

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    Well, it's great to hear from you. Ar, as in Arkansas??
     
  6. Steve 74gtQ

    Steve 74gtQ In Overdrive

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    Check your vac advance and your accelerater pump.
     
  7. ribald1

    ribald1 Banned PLATINUM MEMBER

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    Just checking, but you did have the vacuum advance disconnected when you set the timing?
     
  8. andrewok1

    andrewok1 In Maximum Overdrive GOLD MEMBER SILVER MEMBER

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    M aybe it needs the little blue pill -HAHAHa what Jeff B asked
     
  9. FordR500GT

    FordR500GT In Maximum Overdrive BRONZE MEMBER

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    Yep. Working great!
     
  10. FordR500GT

    FordR500GT In Maximum Overdrive BRONZE MEMBER

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    Nope.
     
  11. Steve 74gtQ

    Steve 74gtQ In Overdrive

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    Check your groand wire inside distributor also you could have a bad pick up coil if you have electronic ignition the movement of the vacum plate causes the wire to make and break a conection.
    Have had that problem with a Chevy that way.
     
  12. FordR500GT

    FordR500GT In Maximum Overdrive BRONZE MEMBER

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    It's a points ignition
     
  13. FordR500GT

    FordR500GT In Maximum Overdrive BRONZE MEMBER

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    You can kinda hear the issue. It even died on me this time.
     
  14. ribald1

    ribald1 Banned PLATINUM MEMBER

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    You have identified part of your problem.
    The vacuum advance has to be disconnected when timing is set. You are lucky is stays running when you step on the gas.
     
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  15. FordR500GT

    FordR500GT In Maximum Overdrive BRONZE MEMBER

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    Reset timing. Same issue
     
  16. FordR500GT

    FordR500GT In Maximum Overdrive BRONZE MEMBER

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    Ok. No idea what I did, but now it runs pretty OK. However, ANOTHER vacuum leak has developed at the back of the carb, and it ran outta gas... Vacuum advance is working g perfect, idle is set at 750
     
  17. ribald1

    ribald1 Banned PLATINUM MEMBER

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    Now that that is out of the way.
    Did you also tune the carb, setting idle and air/fuel with the advance disconnected?
    If not, you can guess the next step.
    When you step on the gas, the engine is in exactly the condition it is in when the v advance is disconnected. I recommend that the vacuum advance be disconnected and left that way until everything is working properly as it just adds an unnecessary variable that can send one in pointless directions.
     
  18. FordR500GT

    FordR500GT In Maximum Overdrive BRONZE MEMBER

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    Ok good point. I got it running way better, but the stumbling is still an issue. I'll continue to adjust the mixture screws to see what happens
     
  19. FordR500GT

    FordR500GT In Maximum Overdrive BRONZE MEMBER

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    Here is the old pushrod, BTW
    received_996999203810551.jpeg
     
  20. ribald1

    ribald1 Banned PLATINUM MEMBER

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    You might want to investigate why it did that.
     

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