Timing issue after replacing spark plugs & wires?

Discussion in 'Troubleshooting & Diagnosis' started by Pre-Strike-'71-Z/28, Aug 23, 2020.

  1. camarochevy1970

    camarochevy1970 Veteran Member

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    worth mentioning, the 383 in my Camaro was setup with 93 octane readily available. When we did power tour in 2017 with it, I couldn't get 93 octane, and for the stops where that was the case, I had a dieseling issue. As soon as I got back to 93 it went away. So I would definitely try a good tank of premium
     
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  2. Pre-Strike-'71-Z/28

    Pre-Strike-'71-Z/28 Striking Z/28

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    I typically shut it off while in reverse since I have to back up to pull into my parking spot. After it shuts off I then shift it to 1st gear. I'm gonna try leaving it in 1st gear before shut off to see what happens.
     
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  3. Pre-Strike-'71-Z/28

    Pre-Strike-'71-Z/28 Striking Z/28

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    Will do and see what happens.
     
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  4. Pre-Strike-'71-Z/28

    Pre-Strike-'71-Z/28 Striking Z/28

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    Don't know the answer to your questions but for sure the valves haven't been looked at for at least 1 year and 3 months (the time I've owned the car).
     
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  5. Pre-Strike-'71-Z/28

    Pre-Strike-'71-Z/28 Striking Z/28

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    Don't know the idle speed setting. How can I find out?
     
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  6. ULTM8Z

    ULTM8Z Veteran Member

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    A leak down test on all the cylinders would probably exonerate the valves and how they're sealing against the seats.
     
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  7. COPO

    COPO Veteran Member Lifetime Gold Member

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    800 rpm for manual trans in neutral.
    750 rpm auto trans in drive.

    Plug gap s/b .035 unless you have a MSD 6AL box then go to .040. Anything larger you will get a hesitation cause I tested .045 and went back to .040. MSD recommends HUGH gaps. Well too large of a gap will put a strain in the ignition components and fry your 6AL box which MSD probably wants to happen so you buy another box.

    If you have HEI then you’d go with .045 gap.

    When you buy the emissions decal for the top of the radiator, the specs will be on it. These #’s are for a 70 and s/b the same for a 71.
     
    Last edited: Aug 24, 2020
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  8. Pre-Strike-'71-Z/28

    Pre-Strike-'71-Z/28 Striking Z/28

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    My ignition is a Street Fire CDI Multi-Spark and my distributor an Accel HEI Super Coil. The gap that I set in the new spark plugs was 0.035 in. Idle speed verified to be 1000 RPMs.
     

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  9. carhead22000

    carhead22000 oldblue

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    as stated before.turn your distributer until you have the highest idle. Drop in back just a hair.then drop your idle back on carb.your timing is off and its compensated with more idle speed.this will cause run on.you can also pop off cap and rotor and check that your springs and weights all move freely..never hurts to free them up..maybe a new curve kit.if you still have backfire and stuff move to the carb.might need a cleaning or just setup right.distributer should fix your run on.hope this helps.
     
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  10. Z-Life

    Z-Life Nasty Member

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    Sounds like timing has too much advance, and idle is def too high. You need to make sure the vacuum advance, and mechanical advance are working. Get a timing light, Set initial timing at idle (800 rpm) then rev the engine to make sure mechanical advance is working you'll see the timing mark advance much higher at higher rpms.

    Do you ever have hard/slow cranking when its warm? That with the engine run on indicate timing has too much advance, any pinging when you accelerate? another indication of too much advance in timing.

    I have ran AC R45TSX spark plugs at .060 gap, TSX stands for extended tip, R45 is the correct heat range, but the extended tips helps burn off more fuel... a lot of engines never burn all the fuel in the cylinders before the exhaust valve opens, the extended tips help with that.

    Good luck
     
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