Backfire and no secondaries

Discussion in 'Troubleshooting & Diagnosis' started by BackBehindTheWheel, Oct 14, 2021.

  1. BackBehindTheWheel

    BackBehindTheWheel New Member

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    Hello everyone.
    I'm new here and hoping for some input. I've just purchased a 1980 Camaro with customizations. It has a 350 4 bolt main, mild cam, Vortech heads, Holly carb (search of stamped number says Avenger 670) and Holley fuel pump. Hydraulic lifters, roller rockers. It sounds as feels mean, but .. It's backfiring thru the carb on startup, once or twice max, with no power off the line and no secondary barrels on kickdown...just another backfire out the carb. It seems to run well when warm, and will run up to driving speed smooth, just not with any jump...and there should be some jump. Apparently it was not driven much these last 2 summers, coming out only a couple of times. Running well when last parked, no changes made to setup, the previous owners Father said his son was just very busy with work and couldn't make time for the car anymore.
    Any thoughts on potential things to look at appreciated. Thanks for reading everyone. Looking forward to participating in the forums.
     
  2. cadillac_al

    cadillac_al Veteran Member

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    My first thoughts are spark plug wires could be crossed or bad cam.
     
  3. biker

    biker Veteran Member

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    With no other background, I would do as much diagnosis as possible. Compression check, look at spark plug condition, look for vacuum leaks, verify plug wires are in correct firing order, check timing with a light, condition of spark plug wires, distributor cap and rotor condition.
    Backfire at startup sounds timing related.
    Welcome to the site!
     
  4. BackBehindTheWheel

    BackBehindTheWheel New Member

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    Thanks for the input guys! I'm currently searching for that special mechanic in my area that will look after this beast. Certainly a "once over" to discover everything I need to know. I found notes on octane boost recipes and a couple empty cans of race gas.. so a going over and inventory is the only way to go considering the missing information. Thank you again guys, happy to be here among others with the passion.
     

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