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Hot Rods 1956 Oldsmobile engine miss

Discussion in 'The Hokey Ass Message Board' started by bobwop, Aug 26, 2014.

  1. bobwop
    Joined: Jan 13, 2008
    Posts: 6,091

    bobwop
    ALLIANCE MEMBER

    My friend came to me with questions that I have not been able to answer.

    His 1956 Oldsmobile with original 324/4V is a great runner. Starts good, too. The 324 was rebuilt some 20 years ago, but we doubt it has 5000 miles on it since.

    His questions are regarding a miss that begins to show up after 15-20 miles of driving. It begins and it barely noticeable. It will progress to the point that it seems like one cylinder is dead.

    If he stops after a short drive and lets the engine cool, it will not be missing when he restarts. But after a bit more driving, when the engine gets up to temp., it will start to miss again.

    When cool, it runs just perfect.

    I know he has changed the plugs. I don't believe much else has been changed.

    could it be a plug wire, the coil, the condenser? I feel it must be something electric. I can't believe it could be points.

    I also can't imagine it to be anything mechanical? There is not a strange noise, other than the miss. Good oil pressure and the temperature stays steady after the themostat opens.

    I want to help him avoid throwing money and parts at his car. any suggestions or ideas?
     
  2. bonzo-1
    Joined: Oct 13, 2010
    Posts: 334

    bonzo-1
    Member

    Tight valve clearance?
     
    loudbang likes this.
  3. Damn... Bonzo beat me! :p

    If you can detect the miss at idle try removing one plug wire at a time and see if you can isolate the weak cylinder.

    If the engine has mechanical lifters you might try readjusting the valve lash on that one cylinder. It might have a valve adjusted just a skosh too tight. When it's fully up to temperature the lash may go away it will just barely keep a valve from fully seating. When the engine cools a bit the lash increases and the valve will close fully like it's supposed to.
     
  4. bobwop
    Joined: Jan 13, 2008
    Posts: 6,091

    bobwop
    ALLIANCE MEMBER

    hydraulic lifters in 324 Olds
     

  5. Kustom292
    Joined: Dec 21, 2008
    Posts: 217

    Kustom292
    Member
    from Winnipeg

    My thought is electrical. Check the cap for a small crack or a defect at one terminal. Check each plug wire for one with higher resistance.
     
  6. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,384

    GMC BUBBA
    Member

    CONDENSOR , EASY TO CHANGE........
     
  7. bobwop
    Joined: Jan 13, 2008
    Posts: 6,091

    bobwop
    ALLIANCE MEMBER

    a good friend told me the same thing Jim. That was going to be the first "money" I had him throw at the car. With you echoing that sentiment, we will get it done for sure and he can test it. After it quits raining!
     
  8. OK. How about fuel tank venting? Maybe add a heat dissipator or insulator between the carb and intake? Does the miss feel consistent like it is only affecting one cylinder?
     
    Last edited: Aug 28, 2014
  9. Dave50
    Joined: Mar 7, 2010
    Posts: 1,751

    Dave50
    Member

    possibly a vacuume leak ?? worn cam?
     
  10. bobwop
    Joined: Jan 13, 2008
    Posts: 6,091

    bobwop
    ALLIANCE MEMBER

    it does feel like it on one cylinder. but that is just an opinion.
     
  11. If it's one cylinder affected by time/heat my money is on something mechanical. And tight valve clearance is an excellent suspect.



    If it's randomness then electrical is more likely.
     
  12. bobwop
    Joined: Jan 13, 2008
    Posts: 6,091

    bobwop
    ALLIANCE MEMBER

    sounds logical
     
  13. Could be a plug wire.
    The do wear out from use on the inside but can look new outside.
    not sure how long they last sitting but 20 years is a long time.

    Next time it starts missing, remove the plug wires one at a time. The one that has the least effect is the culprit cylinder. Switch a wire and see if the problem moved with the wire , change it and repeat it for that cylinder.

    To prepare for this test, while the engine is cold make sure the boots aren't stuck. A little Dab of dielectric grease. Get your plug boot pliers ready Go get it warmed up and missing and have at it.
     
    bobwop likes this.
  14. I've had spark Plugs porcelain separate... coils, condensers and wires do exactly that at running temps.

    Funny you haven't experienced those with all the cars you've had!

    Of course mine had the cheapest parts installed so I've been Blessed with all that stuff!

    Posted using Full box of Crayons on the Kitchen Walls App!
     
  15. inthweedz
    Joined: Mar 29, 2011
    Posts: 403

    inthweedz
    Member

    Inlet manifold leak/cracked??
     
  16. Says they're hydraulic lifters but I don't know how or if they're adjusted on this engine. Could a single lifter be overadjusted or bottomed out? Kind of sounds like maybe a lifter pumping up, holding a valve open, then eventually bleeding back down. But I'd associate that more with higher RPMs and running it into valve float.
     
  17.  
  18. I once found a miss problem on a 50 olds for a freind. One of the distributor point cam lobe were shorter. Caused a miss problem. He had a lot of shops try to fix it. I found it by measuring point gap of each lobe.

    wayne h
     
  19. d2_willys
    Joined: Sep 8, 2007
    Posts: 4,109

    d2_willys
    Member
    from Kansas

    Pull the car into a garage where it is dark after vehicle has warmed up. Look at cap and wires for arcing. Sounds like disty cap and or wires.
     
  20. Tight sticky gooey guide that swells with heat and hangs open.
     
  21. J&JHotrods
    Joined: Oct 22, 2008
    Posts: 549

    J&JHotrods
    Member

    Whether it's ignition-related or not, to diagnose I would pull one plug wire at a time to isolate the problem to the affected cylinder, then start tracing down the problem. Sounds secondary ignition-related to me as well(plug wire, plug, bad cap and/or rotor). Another way I use to diagnose(instead of pulling wires one at a time) is to take a squirt bottle filled with water and lightly mist the plug wires from cap to plug, or where any plug wire is touching a metal object. Make sure it's dark so you can look for arcing; it will also short to ground and the misfire will be present as well. This method is not only a great way to find a shorted wire, but you will find EXACTLY where the short is in the wire by where it's arcing to ground.
     
  22. If it turns out to be anything valvetrain related I'll buy you a beer and you can buy me a beer! :rolleyes:
     
  23. bobwop
    Joined: Jan 13, 2008
    Posts: 6,091

    bobwop
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    I am going to install a new condenser for him tomorrow. But the forecast is awful, so he may not drive it until next week. Will keep you posted.

    thanks for all the insight fellows!
     
  24. You're on :)
    It's not easy to fix 'em across the interweb.
     
    ClayMart likes this.
  25. bobwop
    Joined: Jan 13, 2008
    Posts: 6,091

    bobwop
    ALLIANCE MEMBER

    condenser is installed. but the weather in not cooperating
     
  26. LOL! I don't care what Bubba says. Replacing a bad condenser may fix any number of running problems... But it's not going to improve the weather! :confused:
     
    bobwop likes this.
  27. junkyardjeff
    Joined: Jul 23, 2005
    Posts: 7,540

    junkyardjeff
    Member

    I have found that bad plug wires get worse when the motor is warmed up.
     
  28. bobwop
    Joined: Jan 13, 2008
    Posts: 6,091

    bobwop
    ALLIANCE MEMBER

    condenser change may be the answer. Test drive yielded no missing and he felt the power was greater and more responsive. Or is that his imagination?
     
  29. belair
    Joined: Jul 10, 2006
    Posts: 8,533

    belair
    Member

    Sounds like you whipped it. I sure miss my 55 2 door.
     
    bobwop likes this.

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