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Technical Misfire question

Discussion in 'The Hokey Ass Message Board' started by Salvarican, Oct 22, 2018.

  1. Salvarican
    Joined: Oct 17, 2006
    Posts: 80


    So i have pulled my hair trying to figure this problem out. Maybe someone can shed some light. I have a 1964 chevy with a 327. Car had been parked for about 6 years, when tried to start the car, it was smoking bad. Its like smoke from unburned gas (burns your eyes). I replaced the gas tank, fuel sending unit, fuel lines, rebuilt carb (4bbl carter), tranny modulator, dist cap, rotor, condenser, spark plugs, wires and points but didnt get rid of the problem. Car runs really shitty and sounds like its misfiring. I did a compression test and got about 135-140+ through all cylinders. Also noticed the oil has fuel in it. Oil smells like gas and the viscosity is bad. Tested the wires and seems like driver side bank (1,3,5,7) have no spark or very minimal spark. What can be causing this problem? By the way, the new spark plugs were black after running them for about half hour.
    chryslerfan55 likes this.
  2. squirrel
    Joined: Sep 23, 2004
    Posts: 48,656


    did you change the fuel pump?
    ClayMart likes this.
  3. Truck64
    Joined: Oct 18, 2015
    Posts: 4,612

    from Ioway

    Get rid of that oil if it has gas in it.

    Did you replace the old condenser with one of those new piece of shit chinesium jobs? Put the old one back in. Absolutely make sure you've a hot fat bluish spark at the plugs.
  4. I've had coils act like that when they tested ok on an ohmmeter. Once I had a coil wired backwards and it acted a lot like that also. Doesn't take much to swap coils with a known good coil.

  5. Spark plugs black deposits, fluffy (dry)
    black or oily (wet) black?
  6. Salvarican
    Joined: Oct 17, 2006
    Posts: 80


    squirrel........Yes i also changed the fuel pump and filter.

    Truck64.... I did change the condenser with Standard ignition along with points and cap

    Shovelheadrider.....most were black dry except for 5 which smelled like it had gas on it
  7. squirrel
    Joined: Sep 23, 2004
    Posts: 48,656


    Tell us about how the choke is working...
  8. Salvarican
    Joined: Oct 17, 2006
    Posts: 80


    Choke seems to be working fine
  9. big duece
    Joined: Jul 28, 2008
    Posts: 6,149

    big duece
    from kansas

    Get that oil out of the pan, put fresh in. Thinned down oil from gas will not protect your bearings, and may scuff the cylinder walls. Then figure out tuning issues. Plug wires? Edit; read about the wires.
  10. sevenhills1952
    Joined: Mar 14, 2018
    Posts: 954


    Another lifetime ago my friend had a '64 Impala 327. His started running rough, smoked. Turned out to be a bad vacuum modulator valve in transmission, sucking trans fluid into carb.

    Sent from my SM-S320VL using Tapatalk
  11. Possibly a high float, but you had the carb apart. Did the float swing freely? A dirty needle valve can let lots of fuel get past it, also the needle and seat that hangs on the float can do it.
  12. Blues4U
    Joined: Oct 1, 2015
    Posts: 5,549

    from So Cal

    I've had brand new plugs foul like that and cleaning them did no good. I thought since they were new that couldn't be the problem, but at the advice of an older more experienced mechanic at work I changed them again and that cured the problem.

    New condenser could be at fault, you wouldn't be the first one to get a brand new condenser that was bad. Try the old condenser.

    Seems strange that the oil would be so contaminated with fuel, if this was just an ignition problem. How long has the engine run in this condition? Long enough for excess unburned fuel to wash down the cylinder walls and contaminate the oil?
    Boneyard51 likes this.
  13. Gerrys
    Joined: May 1, 2009
    Posts: 327


    Is this a dual point distributor? could be point/condenser for that bank.
  14. Not how they work on an American V8
  15. First of all, it's very hard for a V8 to have weak spark on only one head, due to the firing order. Also a dual plane manifold won't let it soot up all the plugs on one head.
    I suggest that you do a re-start on your diagnostic procedure. As stated , start with new plugs. Then switch all the wires from left to right and see what happens. Then re-evaluate the situation.
  16. Boneyard51
    Joined: Dec 10, 2017
    Posts: 4,931


    Double check the carburetor rebuild. Kinda hard for one bank to have weak spark, not saying impossible, but sounds like carb to me. I’ve seen some carbs that seem to “ fight” a rebuild. If you can, substitute a known good carb in its place.

    I had a Holley on. PU that I tried and tried to get to run properly! After a while I “fixed” it by replacing it with a new one! Lol

    Last edited: Oct 23, 2018
    bobss396 likes this.

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