1970 Z28 Engine idle problems

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

  1. twozs

    twozs Veteran Member

    8,418
    78
    Aug 5, 1999
    hopewell jct ny
    Manual , set carb screw ... auto set solinoid screw
     
  2. Crazy4camaro

    Crazy4camaro Veteran Member

    201
    10
    Dec 30, 2015
    Greenville SC
    Double check your spark plug gaps. .035 for factory dist, .045 for HEI
    A weak spark from a coil will cause this too.
    Also make sure your gas is fresh.
     
  3. cadillac_al

    cadillac_al Veteran Member

    512
    33
    Apr 22, 2015
    Maine
    I always blame a vacuum leak when a vehicle doesn't idle in drive. I don't know your idle speed so it could be idling high in the power circuit in neutral then drive takes it down a hair into the idle circuit which is too big a jump. Just my .02.
     
  4. xten

    xten Veteran Member

    745
    247
    Sep 24, 2014
    Pittsburgh, Pa.
    ^^^^ That was going to be my suggestion. Mine's a stick, but it would stall when the A/C compressor kicked on. It was a leak in the line to the brake booster.
     
  5. rocket dawg

    rocket dawg Veteran Member

    204
    11
    May 5, 2015
    Grand Rapids Mi
    Have someone check your timing when in drive vs. in neutral/park. If it a huge difference, the problem is in the dizzy. If no difference, look to the carb or vacuum leaks. process of elimination.
     
  6. junkyardZ28find

    junkyardZ28find Veteran Member

    712
    5
    Mar 4, 2012
    des moines, iowa
    Ok-quick question here and forgive my ignorance to original Z owners here if Im wrong-but with a solid lifter 350 in a 70 LT1 I didnt think you could get AC and an auto trans behind it-am I wrong? I could look this up I guess but Im being lazy lol
     
  7. Dave Nelson

    Dave Nelson Veteran Member Gold Member

    3,076
    330
    Dec 19, 2003
    Vineland N.J USA
    AC was not available on the 1970 Z/28, Turbo 400 (auto) was available. I bought one new with the turbo 400.
     
  8. twozs

    twozs Veteran Member

    8,418
    78
    Aug 5, 1999
    hopewell jct ny
    I guess were just going to ignore the fast idle solenoid
     
  9. Rdobbs1977

    Rdobbs1977 Veteran Member

    261
    8
    Dec 1, 2014
    TN
    never heard this one before. can you explain further?
     

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