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Stupid noob question on idle quality

Discussion in ''Da Nailhead' started by AZ 55 Riviera, Feb 1, 2025.

  1. AZ 55 Riviera

    AZ 55 Riviera New Member

    Recently picked up a 55 Special with what should be a 264. Now I am assuming a 55 Buick would leave the factory running really smooth. But this sounds like it has a performance cam swap. Did they idle like a new Lexus or was there some bumpity bump from the factory.
     
  2. 12lives

    12lives Control the controllable, let the rest go

    Anything is possible in the 70 years that car has been around, but in 1955 a nailhead should have a smooth sewing machine like idle. Check for vacuum leaks.
     
    AZ 55 Riviera, VET and gsgtx like this.
  3. CJay

    CJay Supercar owner Staff Member

    "Mr 61 Buick" told me recently that the nailheads idled rough until 61. I seem to recall him telling me they changed the cam in 62 to make the engine idle smoother. So what your experiencing might just be normal
     
    AZ 55 Riviera likes this.
  4. VET

    VET Navy Vet, Founders Club

    Check your spark plugs wires.
    One bad wire can create a lumpy sound. Vet
     
    AZ 55 Riviera likes this.
  5. AZ 55 Riviera

    AZ 55 Riviera New Member

    She is running rich, can smell it. I will start checking for spark. Am going to get a bung welded on for my O2 sensor and A/F digital gauge. But how can you tune a carb running on 7 cylinders lol...
     
  6. CJay

    CJay Supercar owner Staff Member

    The first thing you might want to do is perform a basic compression check. Make sure you don't have a low cylinder
     
  7. AZ 55 Riviera

    AZ 55 Riviera New Member

    Plug wires look newer. Passenger side of the distributor next the the vacuum advance has a hose coming straight up with a bolt in the end of it. So not sure what is up with that. 12lives mentioned vacuum leak. So will have to go through the vacuum system. Wifey is dead set on hitting her GF's car show this eve so I don't have time to play with her more. But something is off somewhere....
     
  8. AZ 55 Riviera

    AZ 55 Riviera New Member

    Previous owner bought the car for $22k and has $8k in receipts. The place doing the work was major expensive and you would think they would have checked to see why she is running so rich. Does not have the running on 7 cylinders idle. Runs smoother than that. Has the lumpy cam idle. But not a 540 lift 108LSA 280 duration rump rump. Just not running like I thought a Buick would run. That random vacuum hose coming up out of the engine though. With the bolt in it...
     
  9. VET

    VET Navy Vet, Founders Club

    Good idea.
    Maybe also a leak down test?
     
  10. CJay

    CJay Supercar owner Staff Member

    Throw a vacuum gauge on it. A vacuum reading will tell us alot
     
    Guy Parquette likes this.
  11. CJay

    CJay Supercar owner Staff Member

    That's basically a compression test in reverse.
     
  12. Babeola

    Babeola Well-Known Member

    Tune up specs have idle at 450 RPM. It is almost impossible to idle rough at that RPM and Buick would not have accepted a rough idle for their buyers.
     
  13. VET

    VET Navy Vet, Founders Club


    The above shows what a running nail head sounds like.
    Hope this helps.
     
  14. VET

    VET Navy Vet, Founders Club

    Sounds like a lot of valve train noise, idle seems good to me. Vet
     
  15. gsgtx

    gsgtx Silver Level contributor

    first thing I would do is look at all 8 spark plugs It should take 5 minutes with a nail head.
     
  16. VET

    VET Navy Vet, Founders Club

    Unless you install a Duel Wideband, you can't check both banks of the engine's A/F ratio.
     
    12lives likes this.
  17. 12lives

    12lives Control the controllable, let the rest go

    Here is an easy check - get one of those temperature guns with the laser lights. Check the temp on each exhaust. They should be close. Sometimes you can spot a hot one (lean) or a cold one (rich). Check at different rpms too, idle, 1000, 2000.
     
    Lucy Fair likes this.
  18. VET

    VET Navy Vet, Founders Club

    Good idea Bill.

    When my 455 gets its tune, I will use my temperature gun to see what heat temps I get.
    Compare that with the Duel Wideband results.

    Never occurred to me to give that a try. :D Vet
     
  19. CJay

    CJay Supercar owner Staff Member

    Who needs a big expensive temperature gun? If you want to know if a cylinder is firing, pour a little water on each port on the manifold
     
  20. VET

    VET Navy Vet, Founders Club

    He said he wanted to see if a cylinder was rich or lean.
    The cheap way if you don't have a Wideband.

    It would be interesting to see if that would work.

    But, first things first, I agree a compression check and a vacuum check are in order.
    Not a bad idea to see if all 8 spark plugs are getting fire also. Vet
     

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