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technical advice requested

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  • technical advice requested

    I curenty am having problems that I need advice on. My 1960 Thunderbird is having stall and backfire problems. This only happens when I put the car into gear and apply the gas and continues as long as I attmept to apply the gas. Breaker points are gapped correctly, timing is good (car sounds great if I give it gas in Park or Neutral). I recently replaced a defective vacuum advance. Any suggestoins to the cause of this problem would be appreciated.x(

  • #2
    RE: technical advice requested

    A vacuum leak somewhere. at an idle you have sufficient manifold vacuum to run fine but... open the butterflys a bit and it rund lean and backfires.

    If you don't have a leak it has to be timing and/or a bad vacuum advance diaphram which you can test by putting a hose on it and suck on the other end. Watching to see if it moves with the distributor cap off. it should move then bend or pinch the hose off and see if it stays there. If it goes back the diaphram or the hose is letting air in.

    Next I'd look at the cap and make sure it's good and on straight. Next the mechanical advance weights.

    The engine is either running very lean or out of time.

    Hope if didn't jump. IF you pulled the distributor you may be one tooth off.

    That's my guess list.


    • #3
      RE: technical advice requested

      One more thing.

      If it had been backfiring and you replaced the vacuum advance because it was bad, it's possible you developed in intake manifold gasket leak under the carb or by the heads.

      With the engine at idle, spray WD-40 along the side intake gaskets at the heads and under the carb.

      If it's sucking air there your RPM's will increase with the richer mixture.

      DO NOT USE GAS!! One backfire and poof no more bird.

      If you fine a leak try tightening everything to the high end of the torque spec's for the bolts and nuts before replacing the gaskets.



      • #4
        RE: technical advice requested

        I having a similar problem. Only difference is mine is popping out of the carb. When I accelerate hard from a stop or when I "get on it" at about 20-35.
        I just replaced the carb and I had the same problem with that old one.

        How many volts should the generator be generating at idle? Does anyone know an approximate gap size to start with on the voltage regulator settings. I am not holding a charge and inturn running the battery down.


        • #5
          RE: technical advice requested

          Looking through the shop manual all I can find is :-

          Generator should be producing 30 amps or more at 1500 rpm - no figure for at idle
          Specifications state that the generator begins to charge at 625 rpm

          No figures for regulator


          • #6
            RE: technical advice requested

            on your charging problem, see what the voltages are at higher rpm than idle. Even if you are discharging at idle, this should be more than compensated for by charging while driving. That said, you ought to see 12.5 or so for starters and eventually 14 or more while driving.

            An ammeter in line would be helpful also to tell you when or if you are actually generating power as opposed to consuming it.

            Assuming the worst, that things have failed in some way, you might start by checking all wiring involved, especially the wires to the generator , which live in kind of a lousy location. Remove and clean the connections and check for broken wires. Same comment at the regulator end. Also make sure your battery is well grounded to both the motor and chasis.

            A possible thing to do is remove the generator and check the brushes for two things: freedom of movement to follow the commutator, and sufficient length.

            At the regulator end, a starting point might be to clean the points with some very fine paper and contact cleaner.

            These failing to improve things, you might haul both the regulator and generator into an "Auto electric" shop where they can comprehensively check and service both as a system and you can put the problem to rest.
            1958 Hardtop
            #8452 TBird Registry



            • #7
              RE: technical advice requested

              The normal range should be 13.6 to 14.2 and any higher you'll cook your battery. Lower and it runs down the charge but I've found if you can hold above 12.6 with a full load on the genetator at 1000 RPM's you should be fine. At idle full load... that's why they went to alternators. It's best to turn it off if you plan to idle for a while if you have a generator or idle it up.