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Hard Starting and Vibration

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  • Engine: Hard Starting and Vibration

    First time posting.

    My Dad purchased a 1948 Champion Starlight Coupe a few years ago. During the test drive prior to purchase everything seemed okay and the car drove remarkably smooth. Once we trailered it home, the car continued to work wonderfully for about 100 miles.

    Then the engine became tough to start but a little bit of ether seemed to do the trick. Once started, it idled smoothly but if we added any throttle at all, the engine would noticeably shake which got worse as the revs increased. This happens whether cold or fully warm. There was never any loud noises that would indicate some sort of mechanical failure.

    I inspected the spark plug wires and a few had some cracks due to dry rot so I replaced all of the wires and plugs. This had no effect. The engine remained hard to start and the off-idle vibration continued.

    I am unfamiliar with Studebakers and I wanted to ask for some advice and/or opinions on what course of action I should take in order to fix the issues I described above. Our goal is to sell the car.

    I plan to go to Dad's this weekend, so I will be able to get answers if you have any questions. I appreciate any help you can give.

  • #2
    Sounds like a fuel problem. Have you checked filter and gas tank for crud?
    78 Avanti RQB 2792
    64 Avanti R1 R5408
    63 Avanti R1 R4551
    63 Avanti R1 R2281
    62 GT Hawk V15949
    56 GH 6032504
    56 GH 6032588
    55 Speedster 7160047
    55 Speedster 7165279


    • #3
      compression ??


      • #4
        Did you mean to say he bought it years ago? If it has been sitting for years you no doubt have old fuel in the carb. and probably other places. If you meant he bought several months ago...

        Nothing wrong with asking the previous owner. Now did it sit for a while before you bought it? If it did the fuel system from tank to carb could be an issue, including the simple things like old rubber hoses that collapse FROM THE INSIDE. The tank has a hose at the very rear of the car from the tank to the main fuel line. No one ever changes that.

        The fact the ether starts it points me to the choke. Are you sure it is closed when cold and open when warmed up?

        The best thing to do with a car new to you is do all the tune up things. Plugs, wires, points, condenser, cap and rotor. Fuel filter, air filter. Fresh gas ,oil change. If you really think it is a fuel problem like in the tank, use a can to run the car before you panic and start dropping the tank. Try some good old carb. cleaner too.

        The forum really appreciates it if guys report back when the problem gets solved too. We all are learning. Welcome to the club...hope you get Turning Wheels.

        This forum and the vendors are terrific. You'll have it running smooth a me. Just don't start changing parts all willy nilly.


        • #5
          It sounds like a fuel issue, since it starts with ether and runs, just poorly. First thing to do on any car that has been sitting any length of time is to thoroughly drain the fuel system, and flush all the lines. In todays world of poor quality gas, it also doesn't hurt to replace all rubber hoses and any filters in the system--before starting. Once a car has been inoperative for some time, evaporating fuel leaves gum and other deposits behind that clog and make movable items like inlet needles stick. Once you have that cleaned out it will probably run like a watch, as it did when purchased.


          • #6
            I would suggest to discontinue with the ether and prime it with gasoline until the problem is solved. First thing I would do is to lift the top off the carburetor and see if there is any water in the fuel bowl. They will run with an ounce of water in the bowl but will act up at times FWIW David


            • #7
              I appreciate all of the advice.

              The car sat for 5 years on consignment before we bought it. The test drive went well after the dealer was able to find a battery. When we got it home it ran well for about a week (~100 miles) and then the symptoms I listed above began. We did not drain the tank right after we bought it but instead just filled it up with ethanol-free gas. One hundred miles worth of that full tank was used before it was parked. That was three years ago and it did not move until last month.

              Last month we decided to get rid of it so we started the troubleshooting in earnest.

              Taking your advice about a likely fuel problem, we will carefully rig up a temporary clean, fresh fuel source and see if it runs any better.

              I neglected to mention that we did replace the points, condenser and cap last week. While checking for spark, I noticed the spark is very weak when compared to a modern car. Is that normal for this 6v system or should the coil produce a similar spark to a 12v system?

              It will be a little while before I am able to report back on the results since I am going out of town but I will be sure to report as soon as I can.

              Again, thanks for the help and the welcome!


              • #8
                The coil wire to a head bolt should produce a hot blue spark at least 1/4" long, and more likely 1/2" long.
                If it's weak and yellow, you could have a bad condenser or weak coil.

                My 1950 Champion also has an off idle vibration, but I haven't looked into it yet. I do know the bellhousing has a mouse hole on the top side, and mice love to get inside. I'm wondering how bad a dead mouse caught in the pressure plate would make it vibrate?


                • #9
                  A couple of observations. Check to see that the vacuum advance diaphragm has not developed a leak. If so, it will cause the rough idle and vibration because it messes up the fuel/air ratio mix. Also, when adjusting the point gap...this is one of the most sensitive adjustments on the car. Make sure you are careful to see that the points meet square to each other. Lately, due to what I think is sloppy assembly, I have had to bend the points set frame to make them meet squarely.When adjusting, be sure to loosen the adjustment lock down screw just enough to allow movement. Loosen it too much, and the adjustment will change when you tighten it to lock it in place.

                  If you are having contaminated fuel issues (water), there should be a distinct odor as poorly ignited, incomplete burning fuel emerges from the exhaust.
                  John Clary
                  Greer, SC

                  SDC member since 1975


                  • #10
                    In 5 years of sitting.....who would guess the car would run with that fuel ??? I'd remove the rubber tank line and drain said fluid for cleaning purposes....might take a while...


                    • #11
                      The points could very well be out of adjustment. The spark is tiny when pull off a plug wire and ground it to the head.

                      This weekend I found the time to do a quick test. The fuel pump appears to be supplying plenty of fuel while cranking. The off-idle vibration happens quickly enough that I doubt the bowl is emptying due to poor fuel flow.

                      My course of action follows:
                      --> All of the comments above have made me realize that I should bite the bullet and drain the tank and put fresh gas in even if it is only to remove the possibility of bad gas being the cause.
                      --> Check points adjustment
                      --> Check timing advance diaphragm

                      Thanks again for the help. I will report back on any progress.