1970 Z28 Engine idle problems

Discussion in 'Troubleshooting & Diagnosis' started by harkz28, Nov 5, 2017.

  1. harkz28

    harkz28 New Member

    14
    0
    Aug 22, 2005
    I have a 1970 RS Z28 fresh LT1 350 factory Holley 780. I installed the MSD 8360. Idles fine in park. But when I drop it in Drive Idle Falls very low when warm. The car almost dies. Do I need to recurve this distributor adjust the carburetor not sure what to do next?
     

    Attached Files:

  2. restore-z28

    restore-z28 Veteran Member

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    Jul 4, 2010
    Vancouver, BC
    Start with making sure your base timing is correct, the I would move onto the carb adjustment. You might be too lean on your air/fuel mixture and the double check your base idle. Might even be a jetting issue, are you running stock jets? You might need to increase the jet size.
     
  3. Dave Nelson

    Dave Nelson Veteran Member Gold Member

    3,083
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    Dec 19, 2003
    Vineland N.J USA
    Were any changes made to the vacuum advance?
     
  4. Gary S

    Gary S Administrator Lifetime Gold Member

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    Apr 14, 1999
    Bismarck, North Dakota
    Remember that with an automatic tranny, the idle speed is set with the tranny in Drive. The idle speed in neutral doesn't matter unless it is extremely high.
     
  5. harkz28

    harkz28 New Member

    14
    0
    Aug 22, 2005
    Thanks for your replies, stock jets in the Holly and the distributor was installed Straight Out of the Box didn't adjust the curve at all. What should idle be in Drive about 650-700?
     
  6. Gary S

    Gary S Administrator Lifetime Gold Member

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    Bismarck, North Dakota
    The tuneup specs for your engine should be on the sticker on the top of the radiator panel.
    Screenshot from 2017-11-05 09-40-30.png
     
    Last edited: Nov 5, 2017
  7. twozs

    twozs Veteran Member

    8,421
    78
    Aug 5, 1999
    hopewell jct ny
    Don’t they ( auto transmissions) cars have a fast idle solenoid from the factory ?
     
  8. Gary S

    Gary S Administrator Lifetime Gold Member

    20,637
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    Apr 14, 1999
    Bismarck, North Dakota
    Some do, some don't. Usually the fast idle solenoids were used for handling air conditioning loads or for later smog engines. In 1970, it probably wasn't needed to handle the tranny and it wasn't needed for smog purposes like 1971 and later.
     
  9. COPO

    COPO Veteran Member Lifetime Gold Member

    15,865
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    Sep 15, 1999
    Ontario, Canada
    Set this?
    Turn adjustment screw until it just touches the throttle lever and turn 1/2 turn more to position the valves.

    [​IMG]
     
  10. twozs

    twozs Veteran Member

    8,421
    78
    Aug 5, 1999
    hopewell jct ny
    Is says right on the sticker you provide to set the solinoid screw on auto trans .
     

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