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1966 283 hesitation - help

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  • 1966 283 hesitation - help

    My 1966 Cruiser - which is becoming locally quite well known among the shops and parts houses, is continuing to give me fits. I had the points, vacuum advance, rotor, cap, plugs, wires and coil replaced with new parts, the 2gv carb has been professionally rebuilt, the PCV valve and hose and fuel filter has been replaced, the gas tank has been checked and is clean, the motor has been timed (but maybe needs it again), but I still have the following symptoms with the 283 motor:

    1. Car is hard to start - must be pumped. The float level has been checked and I am told it's OK. The accelerator pump works fine.
    It's hard to start whether it's hot or cold. The choke is set correctly and opens correctly.

    2. Hesitation on medium slow or faster acceleration while OUT of gear. We changed the dwell of the points and that helped a little, but there is still some hesitation. Before the points were adjusted again we had a backfire (with flames!) through the carb during one quick acceleration. All this is while the car is sitting - out of gear.

    3. There is a point when the car will idle nicely (don't touch the pedal!), but there is evidence of a very slight miss on one of the cylinders.

    4. The engine dies easily when put into gear. The idle speed is at or already above specs. Even if it's all warmed up, it dies easily in gear. The last time I drove it I had to pump madly and put it in low gear to keep the thing going so I could get up a small hill.

    The car used to run OK before the carb was rebuilt until one day when it SUDDENLY started running horribly half-way home from a gas station where I had put in more gas. The other components had already been replaced. So I was told it was the carburetor. It did need work, but it did not really fix what happened.

    I don't understand, I've spent lots of money and the car is still not really drivable [V]. Could it all be timing? The breaker plate moves, but maybe it's not moving well? I don't know.

  • #2
    It could easily be the timing. What is your setting at idle with the vacuum advance disconnected?

    I have a Delco window on my Stude motor and I noticed that the rotor, when tightened dowm was limiting the centrifugal advance. That wouldn't really effect off the line acceleration, but it is something to check.

    Is your vaccuum advance connected so that it is full vacuum at idle or ported vaccuum, only active when the carb opens?

    R2 R5388

    Comment


    • #3
      The choke may not be working as well as you think, Scott.

      Here's what can happen on those old Rochester 2GVs: When you install the air cleaner and tighten down the wing nut, the bridge across the top of the air horn (on which the stud is mounted) can pull in slightly on the sides of the carb, especially if you crank down hard on the wing nut...or if it has been cranked down previously, repeatedly.

      The air horn body pulls in on the sides just enough to squeeze the choke plate so the plate binds in the air horn and doesn't work right. Of course, when you spin off the wing nut and remove the air cleaner assembly to take a look, the choke appears to work fine because that slight pressure on the air horn sides has been relieved.

      On one of those carbs, I had to remove the choke plate and slightly file on the sides of the plate, making it a little narrower to accommodate the fatigued carb air horn. That let the choke work properly, fixing the car.

      There may be other problems, too, of course; I'm not saying that's all that's wrong with your car. But it is a place to start looking that is out of the ordinary. BP
      We've got to quit saying, "How stupid can you be?" Too many people are taking it as a challenge.

      Ayn Rand:
      "You can avoid reality, but you cannot avoid the consequences of avoiding reality."

      G. K. Chesterton: This triangle of truisms, of father, mother, and child, cannot be destroyed; it can only destroy those civilizations which disregard it.

      Comment


      • #4
        If you've changed the dwell, go back and check the timing. One degree of dwell is about equal to one degree of initial advance.

        Sounds to me like most of the problem is with the fuel system if "it used to run good before the carb was rebuilt". I'd take the carb back to the professional rebuilder. A check ball could have been left out, for example.

        I'd also look for proper fuel flow. Check the output from the fuel pump.

        Check compression. Might need a valve job if one or more cylinders are very low (although unlikely that this would create a SUDDEN problem)

        Check for vacuum leaks.

        Get Dwain G. involved. He could most likely diagnose this one telepathically (even though it is a Chevy <g&gt

        -Dick-

        Dick Steinkamp
        Bellingham, WA

        Comment


        • #5
          As Bige says....timing, raise it a bit.

          Second, the carb. rebuild...........
          Just because a "professional" did the work...doesn't mean squat.
          Years ago, my grandmothers Pontiac Tempest, 326cu.in. with a two barrel needed a tune-up. I did'nt have time so she took it to the dealer she normally went to. They "replaced" the original with a "professionally" rebuilt carb.
          She called me complaining....
          Hard to start, hesitations.

          Through a LONG process of trying to figure it out. I narrowed it down to the "professionally" rebuilt carburetor! After buying "five" carburetors.....I mixed and matched parts for two weeks. I finally hit upon the "combination" of parts that got the car down the road at 99% correct.

          All that is to say...when a rebuilder gets carburetors from...Caifornia, New York, Florida....Colorado... All these require different carburetor calibrating....other than just jetting.
          The rebuilder takes'em apart...tosses the parts in like part boxes, clean all of it, grabs any part that'll bolt up and tighten the screws. One part from CA., one from CO....you get the idea.

          You my need to do some playin with it.

          Comment


          • #6
            I should mention that the professional carb rebuild was done by a well known Studebaker vendor on the east coast. I'm in Minnesota, so shipping the thing back and forth is time consuming and expensive. I believe I asked him about the check ball and other things that could be wrong. He not saying it's impossible there's something wrong with the carburetor, but he does say that the vast majoroty of problems pinned on carburetors turn out to be electrical issues. He also says that the 2GV is so incredibly simple as carburetors go he can't think of anything that would result in some of the symptoms I'm describing.

            It does have a one year warranty, so he is perfectly willing to have another look at it. Too bad I don't live closer.

            By the way, he rebuilt my original core to factory specs. I didn't trade my core in for another unit that was already rebuilt. So I know this one was working (even though it was a mess) before. The suddenness of the rough running before I had the thing rebuilt really makes me think it can't be the carburetor at the base of my problems. Of course, wierd things often happen in cars, so who knows? I will be limping it back to the shop that worked on it so they can have another look. I've done about as much as I can at home, I think...
            "Madness...is the exception in individuals, but the rule in groups" - Nietzsche.

            Comment


            • #7
              What you can do at home is advance the timing. If you don't have a light, mark the present position of the distributor, if you have a light hook it up and note your starting point. Loosen the distributor and move it in the direction that makes the engine rpm increase. A movement of 1/2 an inch at a time would be safe. Snug it back up and see if your condition improves. I'm assuming that you aren't using a timing light, so if it improves, leave it alone and have your technician concentrate on the timing. If there is no change at all in your symptoms, move it back to where it was originally. No harm, no foul.

              Your sudden change in performance could be something as simple as a loose distributor moving while you were driving.

              The other thing I thought is a vacuum hose, broke or popped off and you are running way too lean, but my gut tells me it's in the distributor/timing.

              R2 R5388

              Comment


              • #8
                It sounds like a vacuum leak to me. It could be at the carb. base, a small hose that was left off, a cracked hose, etc.
                Gary L.
                Wappinger, NY

                SDC member since 1968
                Studebaker enthusiast much longer

                Comment


                • #9
                  Lets go back and read the IP.

                  "one day when it SUDDENLY started running horribly half-way home from a gas station where I had put in more gas."

                  I didn't see anything about cleaning out the tank, could it be a case of bad gas?

                  Tom Bredehoft
                  '53 Commander Coupe
                  '60 Lark VI
                  '05 Legacy Ltd Wagon
                  All Indiana built cars

                  Comment


                  • #10
                    Hi Tom,

                    The idea of bad gas came up, but I've put in more since then and it still runs oddly. It might have contributed to it, but I would think it would be mostly gone by now. The really strange thing is how healthy the engine can sound at times when it's warmed up a little, even revving it, but put it in gear and it goes bad really easy and dies after a few feet of moving the car. I forgot to mention that the fuel pump and plugs are also new.

                    I'm going to try advancing the timing when I get a chance, but if my Studebaker luck holds like it it has the last few years nothing I do will make a difference. I guess I'm pretty discouraged, but eventually the problem should be found.

                    I also considered that maybe the rubber part of the tube that feeds the vacuum to the advance is collapsing. I might just replace it and see if that makes a difference, too.

                    I wonder what effect the intake and exhaust valves can have on the system. My mechanic thinks it could be something to do with the valves. I'll probably have him do a compression and leak test. A compression test was done last year and I believe it was ok, but maybe things have changed since then. The car sat unused for at least 2 years, I think. Maybe something was already marginal.
                    "Madness...is the exception in individuals, but the rule in groups" - Nietzsche.

                    Comment


                    • #11
                      Do a compression test. I'm thinking fiber gear going, and cam timing off by one tooth?

                      nate

                      --
                      55 Commander Starlight
                      62 Daytona hardtop
                      http://home.comcast.net/~njnagel
                      --
                      55 Commander Starlight
                      http://members.cox.net/njnagel

                      Comment


                      • #12
                        You aren't anywhere near New Jersey are you? I would love to fix your car for you.

                        Vacuum advance won't cause the problems that you are describing. The only thing I would say to check re the vacuum advance would be that any adjustments should be with it disconnected.

                        The valve diagnosis scares me, last resort and shoud be verified by good diagnostic technique.

                        If you would like to call me at work I could walk you through some things to check. 973.992.9100 ask for Ernie 9am-9pm, Thurs and Friday.

                        R2 R5388

                        Comment


                        • #13
                          I had a similar problem once. It baffled me for days, until I started the engine at night and lifted the bonnet. There it was, I could see electrical arcing from one plug lead. When increasing engine revs, I could see more arcing from another lead.
                          Found it by sheer accident, but new leads and better routing (away from sharp edges) solved my problem that time.
                          It's easy to check, so give it a go. Just maybe ..............
                          /H

                          Comment


                          • #14
                            You have checked fuel pressure right?
                            I don't know if your running a mechanical unit or electric,but bad fuel pumps have caused me a lot of greif,and a lot of the symptoms you describe.
                            Just because its"brand new", or rebuilt,don't mean squat.Ive had new ones fail withen the first few miles.
                            It may be getting all the fuel thats needed,untill the engines put under load.
                            Get a good pressure gage,that reads from 0-30 psi.Install it right at the carb,after the filter,and watch it as the engine is reved.
                            You should have 6-9 psi,any less than 6 and your probaly starving,and going over 9 is not good either.

                            Comment


                            • #15
                              Your Rochester carb originally had a small filter located inside the fuel inlet fitting on the carburetor top. A load of bad gas could partially plug that filter. Lacking a filter, some junk may have gotten into the carb. jets.

                              Dwain G.

                              Comment

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