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225 running rough

Discussion in 'Jeepster Commando and Commando Tech' started by DLS145, Mar 27, 2011.

  1. Mar 27, 2011
    DLS145

    DLS145 New Member

    Columbia Gorge,...
    Joined:
    Jun 6, 2010
    Messages:
    4
    Hello,
    Since buying my Jeepster about 6 months ago I have read alot of posts on this site but have not had a reason to post my own question until today.
    My Jeepster is '67 with a '71 225 in it. I recently replaced the stock intake manifold and carburetor with 4 barrel holley carb. and offy intake manifold. The engine runs rough when it warms up, the 2-4-6 cylinders are running weak (about 40 rpm drop when spark plug wire is pulled), and foul the plugs. The odd cylinders are strong (approx. 120 rpm drop). The #2 cylinder is the weakest with a 20 rpm drop when the plug wire is disconnected. RPM drop is the same across all cylinders when the engine is cold.
    Any help resolving this issue would be greatly appreciated.
     
  2. Mar 27, 2011
    jpflat2a

    jpflat2a what's that noise?

    Riverside CA
    Joined:
    Jul 30, 2003
    Messages:
    7,915
    I would do one of two things,
    okay maybe both:
    A) connect a vacuum gauge
    B) do a compression test

    If the problem started immediately after the manifold/carb change, then either a bad intake gasket or a carb problem.
     
  3. Mar 27, 2011
    Patrick

    Patrick Super Moderator Staff Member

    Los Alamos, NM
    Joined:
    Sep 22, 2002
    Messages:
    8,372
    I'd check the compression first, but have you tuned the carb?
     
  4. Mar 28, 2011
    DLS145

    DLS145 New Member

    Columbia Gorge,...
    Joined:
    Jun 6, 2010
    Messages:
    4
    The compression test showed all cylinders between 120-140"
    The vacuume gauge read 18-20"
    The vacuum gauge was very jumpy.
    I have tryed tuning the carb. (adjusting curb idle screws) could one of the jets be clogged? Somone suggested removing the curb idle screws and spraying the jets with WD-40, is this a good idea, or would carb cleaner be a better solvent to use?

    I also replaced the Distributor but it was tested and I was told it was working fine. (Points type dist.)
     
  5. Mar 28, 2011
    SepotJeepster

    SepotJeepster bsepot7

    Greenwich, CT
    Joined:
    Oct 30, 2008
    Messages:
    44
    My 225 was doing the same about 2 years ago. I am putting off a rebuild for as long as possible. Try a couple of tanks using high test fuel. 93 octane or better. My motor cleaned up pretty well, and it even stopped knocking.

    Not sure if your problems are the same, but my 2 cents anyway...
     
  6. Mar 28, 2011
    jpflat2a

    jpflat2a what's that noise?

    Riverside CA
    Joined:
    Jul 30, 2003
    Messages:
    7,915
    the readings appear good but the jumpy vac gauge needle is bothersome
    needle would like to be somewhat steady
    possible vac leak or timing adjustment
     
  7. Mar 29, 2011
    DLS145

    DLS145 New Member

    Columbia Gorge,...
    Joined:
    Jun 6, 2010
    Messages:
    4
    I sprayed carb cleaner all around the manifold and carburetor, and there didn't appear to be any outside vacuum leaks. Maybe an internal leak? I guess I'll take the manifold off and reinstall this weekend.
     
  8. Mar 29, 2011
    w3srl

    w3srl Semi-homeless in Florida Staff Member

    Port Orange, FL
    Joined:
    Nov 6, 2002
    Messages:
    3,959
    Sooting up the plugs on one bank and weak power on that side would seem to indicate an odd-fire ignition issue. You mentioned changing out the distributor, are you SURE that the new one is for an odd-fire? An even-fire distributor will run in an odd-fire engine and it will give some of the symptoms you describe.
     
  9. Mar 30, 2011
    DLS145

    DLS145 New Member

    Columbia Gorge,...
    Joined:
    Jun 6, 2010
    Messages:
    4
    The Distributor is a delco that someone built into a type of hybrid points/HEI distributor. The guy that built it told me he tested it 2 different 225 engines and it performed fine. I really have no way of verifying this except to replace it with a known good dist. but I don't have access to one.
    Ignition timing was what I initially suspected was the problem, maybe I have to purchase a new one and try that before I pull the intake manifold and reinstall.
     
  10. Mar 31, 2011
    w3srl

    w3srl Semi-homeless in Florida Staff Member

    Port Orange, FL
    Joined:
    Nov 6, 2002
    Messages:
    3,959
    Look inside the distributor, under the rotor. If there are three "points" on the distibutor shaft to trigger the HEI then it is an odd-fire distributor. The corresponding "trigger" points on the ignition module inside the distributor will be unevenly spaced on an odd-fire, and evenly spaced on an even-fire engine. This article from the tech pages will help clear things up for you: http://www.earlycj5.com/wordpress/wp-content/uploads/2009/05/HEI-Even-To-Odd-Instructions.pdf
     
  11. Apr 17, 2011
    mojerry

    mojerry New Member

    Joined:
    Jan 8, 2007
    Messages:
    39
    I had a similar situation, with my 71. After spending a ton of money, and not finding a problem, I took it to a really good mechanic. He discovered a huge vacuum leak in the brake booster. He disconnected the booster and plugged the line, and it ran perfectly. Go figure. If you have power brakes, it's worth a look.
     
  12. Jul 4, 2011
    billybbean

    billybbean Member

    Kemmerer, Wyoming
    Joined:
    Apr 29, 2010
    Messages:
    55
    I had the same problem with my 225 in my cj5. It turned out it had a clogged tube in the carb. Left side was just dumping fuel.
     
  13. Jul 9, 2011
    donald

    donald don lienhard

    Larsen, Wi.
    Joined:
    May 17, 2006
    Messages:
    26
    I have an odd fire and it ran really rough,back fire ect.,when I bought it. What I found out was the The number one spark plug wire on the distributer was in the wrong position.Every thing in the books is for the even fire.I took the number one plug wire and went one spot counter ckock wise,then did the normal firering rotation on the cap. My two cents worth. Been running for five years now with no problem.
     

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