1973 Camaro Z28 Acceleration problems.

Discussion in 'Troubleshooting & Diagnosis' started by Fume, May 11, 2021.

  1. Postmech

    Postmech Member

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    What Biker said.
     
  2. 3PedalJones

    3PedalJones New Member

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    Check the impedance of your coil and look for any cracks in the insulators on both the coil and distributor cap. I found the replacement coil on my '72 was incorrect - a 3.0 Ohm instead of a 1.5 Ohm, and once I replaced it the same kind of misfiring in that RPM range I had went away. Another idea is to check everything out at night in the dark - see if you have any visible arcing between wires or around the distributor cap and coil insulators.
     
  3. T/A Tom

    T/A Tom Member

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    Have you checked the ignition coil? Not exactly sure what you mean when you say it “sounds like a Harley” at times. This could be so many things. How old are the rubber fuel lines? They can collapse at higher RPM and cause the car to kind of “lay down”. So many possibilities here...
     
  4. T/A Tom

    T/A Tom Member

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    Yeah, 10 psi is pretty high...
     
    Last edited: May 14, 2021
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  5. Bentley

    Bentley Veteran Member

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    I would still replace your fuel filter. Fuel volume would be my concern..
    Have you had the carburetor apart?? Possible plugged passages or gunk in the float bowls.. I have had this happen in my Carbureted cars I have in recent years.. Its that wonderful fuel we have now.....
    I saw this happen a few times years ago.. Some exhausts had a pipe within a pipe.. The inside pipe collapses and plugs up the exhaust with no way to tell from the outside... Drop your exhausts at the exhaust manifolds and see how it runs then....
     
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  6. STUCKINCALI

    STUCKINCALI New Member

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    10 psi at idle, what carb are you running? are you running a regulator on it as well? Holley likes 6psi, Edelbrock likes 5.5/6psi max. The other points brought up being springs in your timing advance, or timing (base, full and any vacuum advance needs to be vetted before diving into anything too spectacular. Has it always run this way or just suddenly? Acute issues as mentioned are likely the culprit... more info on the motor and car... exhaust size? muffler types? solid or hyd cam? roller? so many things to consider... I''m going with something ignition/timing-related. What ignition box/distributor are you running? Carbon arcing under the cap? bad rotor? coil voltage? ballast resistor? the list is staggering.
     
  7. nuhmizer

    nuhmizer Veteran Member

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    That happened to me and I found that my distributor was bad. When I took it out it was gummed up and didn't turn freely
     
  8. Gerald Reyenga

    Gerald Reyenga New Member

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    Based on the checks and symptom, I suggest the problem is not ignition but in the carb. If you have Holley 4150 I would pull both metering blocks and check all four main jets for plugging. Reset the flow levels when you re assemble. You are probably running lean in the flat spot from a partially plugged jet.
     
  9. PbFlinger

    PbFlinger New Member

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    Many years ago, I had a similar problem with a 1973 Olds Cutlass. I pulled my hair out over this for weeks. Replaced the entire ignition system, New fuel pump, new carb, new exhaust. In my case it turned out to be that the sock on the fuel pick up inside the tank was degraded. It had a nylon looking mesh sock on it, and something had caused the material to swell up, closing the mesh to where it would barely pass any fuel. Confusing thing was, that pulling the fuel line off of the carb, and putting a line into a bucket, that seemed to pass great gouts of fuel. On the suggestion of a knowledgeable friend, I dropped the tank and found a sock in that condition. Being poor at the time, I just sawed it off and it ran like a raped ape. Well, more like a bored tortoise. It was a stock 73 350 Cutlass after all. But it was back to normal anyway.
     
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  10. STUCKINCALI

    STUCKINCALI New Member

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    So... is this flat spot only between 2,500-3,500 and then you have power again after 3,500 or is it just dead after 3,500? Are you running a vacuum secondary carb or mechanical? Make? Model? Help us sort this out for ya...
     

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