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Re: [AirVW] 1200 VW

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  • Harold Hadaller
    There is nothing exactly magic about 25 degrees advance. Over the years it was found to be a completely safe setting without fear of being too advanced.
    Message 1 of 11 , Jun 1, 2002
      There is nothing exactly magic about 25 degrees advance. Over the years it
      was found to be a completely safe setting without fear of being too
      advanced. However, very few engines are timed as retarded as this ans
      generally run a few degrees advanced from this. It also gives more power.
      In automobiles it is very easy to lug and engine as cause pinging and
      detonation. It is impossible to put an aircraft engine under such a load.
      The basic problem with the mag is that it is either in the retarded/start
      mode or the full advance mode so at 1000 to 1500 rpm it is rather advanced
      for a normal running engine. But we never operate our engines under 2500
      rpm or so when under load. I would have a tendency to push the advance a
      bit. The Continentals run 26-28 degree settings depending on the engine.

      Hal


      ----- Original Message -----
      From: "Tom Cummings" <tomlc@...>
      To: "VW Airlist" <AirVW@yahoogroups.com>
      Sent: Saturday, June 01, 2002 10:55 PM
      Subject: [AirVW] 1200 VW


      > Hello Volksfolkes!
      > I have made a little more progress on the never ending saga of the 1200 VW
      > conversion.
      > After running it a few hours with a distributor system and a stock
      downdraft
      > VW carb, I changed over today to a Fairbanks/Morse magneto. Keeping the
      > downdraft carb for now reduces the variables at this stage.
      > Well it runs. And I am learning more about mags as I go along. I did make
      my
      > adjustment slots in the mounting plate a little bit off but I came pretty
      > close for a beginner. I could only adjust the timing to 27 degrees BTDC
      > instead of 25, so tomorrow I will have to remove the mag and file the
      > plate's slots a little bit more. I would have expected the engine to ping
      at
      > the 32 degrees BTDC at which it first fired, but it didn't. And I didn't
      > understand why. As I continued to retard the mag several times and restart
      > the engine, I got as close to 25 degrees BTDC as I could. But it is up and
      > running with the mag as I had hoped. After I adjust for a few more
      degrees,
      > I plan to install an updraft carburetor. Again, changing one variable at a
      > time.
      > One thing about the mag that surprised me most was that to retard the
      > timing, I had to rotate the mag's housing in the opposite direction than
      > which the rotor turns. Not like a distributor. I have not figured out why
      > yet. The reduction gearing I assume.
      > Maybe by Sunday evening I will have it going better. Got about 3000 rpms
      so
      > far - using a big car muffler.
      > Tom
      >
      >
      >
      > To unsubscribe from this group, send an email to:
      > AirVW-unsubscribe@yahoogroups.com
      >
      >
      >
      > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
      >
      >
      >
    • Jack Lockamy
      Hal, Not sure what mag/impulse coupler Tom is using but the Slick 4216 has a 25 degree lag. So if you statically time the mag at 27 degrees BTDC, what you
      Message 2 of 11 , Jun 1, 2002
        Hal,

        Not sure what mag/impulse coupler Tom is using but the Slick 4216 has a 25 degree lag. So if you statically time the mag at 27 degrees BTDC, what you actually have is a mag that fires at 2 degrees BTDC. Not bad, but I would probably go to 32 degrees BTDC static (actually firing at 7 degrees BTDC).

        Jack
        ----- Original Message -----
        From: "Harold Hadaller" <flyhal@...>
        To: <AirVW@yahoogroups.com>
        Sent: Saturday, June 01, 2002 7:27 PM
        Subject: Re: [AirVW] 1200 VW


        > There is nothing exactly magic about 25 degrees advance. Over the years it
        > was found to be a completely safe setting without fear of being too
        > advanced. However, very few engines are timed as retarded as this ans
        > generally run a few degrees advanced from this. It also gives more power.
        > In automobiles it is very easy to lug and engine as cause pinging and
        > detonation. It is impossible to put an aircraft engine under such a load.
        > The basic problem with the mag is that it is either in the retarded/start
        > mode or the full advance mode so at 1000 to 1500 rpm it is rather advanced
        > for a normal running engine. But we never operate our engines under 2500
        > rpm or so when under load. I would have a tendency to push the advance a
        > bit. The Continentals run 26-28 degree settings depending on the engine.
        >
        > Hal
        >
        >
        > ----- Original Message -----
        > From: "Tom Cummings" <tomlc@...>
        > To: "VW Airlist" <AirVW@yahoogroups.com>
        > Sent: Saturday, June 01, 2002 10:55 PM
        > Subject: [AirVW] 1200 VW
        >
        >
        > > Hello Volksfolkes!
        > > I have made a little more progress on the never ending saga of the 1200 VW
        > > conversion.
        > > After running it a few hours with a distributor system and a stock
        > downdraft
        > > VW carb, I changed over today to a Fairbanks/Morse magneto. Keeping the
        > > downdraft carb for now reduces the variables at this stage.
        > > Well it runs. And I am learning more about mags as I go along. I did make
        > my
        > > adjustment slots in the mounting plate a little bit off but I came pretty
        > > close for a beginner. I could only adjust the timing to 27 degrees BTDC
        > > instead of 25, so tomorrow I will have to remove the mag and file the
        > > plate's slots a little bit more. I would have expected the engine to ping
        > at
        > > the 32 degrees BTDC at which it first fired, but it didn't. And I didn't
        > > understand why. As I continued to retard the mag several times and restart
        > > the engine, I got as close to 25 degrees BTDC as I could. But it is up and
        > > running with the mag as I had hoped. After I adjust for a few more
        > degrees,
        > > I plan to install an updraft carburetor. Again, changing one variable at a
        > > time.
        > > One thing about the mag that surprised me most was that to retard the
        > > timing, I had to rotate the mag's housing in the opposite direction than
        > > which the rotor turns. Not like a distributor. I have not figured out why
        > > yet. The reduction gearing I assume.
        > > Maybe by Sunday evening I will have it going better. Got about 3000 rpms
        > so
        > > far - using a big car muffler.
        > > Tom
        > >
        > >
        > >
        > > To unsubscribe from this group, send an email to:
        > > AirVW-unsubscribe@yahoogroups.com
        > >
        > >
        > >
        > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
        > >
        > >
        > >
        >
        >
        >
        > To unsubscribe from this group, send an email to:
        > AirVW-unsubscribe@yahoogroups.com
        >
        >
        >
        > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
        >
        >
        >
      • Paul&Bridget
        Tom About your mag dilemma. Mags, at least the Slick and Bendix variety, are just like a distributor. On the back of a VW engine, if you turn the mag housing
        Message 3 of 11 , Jun 1, 2002
          Tom
          About your mag dilemma. Mags, at least the Slick and Bendix variety, are
          just like a distributor. On the back of a VW engine, if you turn the mag
          housing in the same
          direction as the crank rotates that will delay the timing. I don't think the
          F-M mags
          are any different. So, I don't understand how it happens like you say. It
          may take
          a moment before the light bulb comes on.

          Paul
          ----- Original Message -----
          From: "Tom Cummings" <tomlc@...>
          To: "VW Airlist" <AirVW@yahoogroups.com>
          Sent: Saturday, June 01, 2002 11:55 PM
          Subject: [AirVW] 1200 VW


          > Hello Volksfolkes!
          > I have made a little more progress on the never ending saga of the 1200 VW
          > conversion.
          > After running it a few hours with a distributor system and a stock
          downdraft
          > VW carb, I changed over today to a Fairbanks/Morse magneto. Keeping the
          > downdraft carb for now reduces the variables at this stage.
          > Well it runs. And I am learning more about mags as I go along. I did make
          my
          > adjustment slots in the mounting plate a little bit off but I came pretty
          > close for a beginner. I could only adjust the timing to 27 degrees BTDC
          > instead of 25, so tomorrow I will have to remove the mag and file the
          > plate's slots a little bit more. I would have expected the engine to ping
          at
          > the 32 degrees BTDC at which it first fired, but it didn't. And I didn't
          > understand why. As I continued to retard the mag several times and restart
          > the engine, I got as close to 25 degrees BTDC as I could. But it is up and
          > running with the mag as I had hoped. After I adjust for a few more
          degrees,
          > I plan to install an updraft carburetor. Again, changing one variable at a
          > time.
          > One thing about the mag that surprised me most was that to retard the
          > timing, I had to rotate the mag's housing in the opposite direction than
          > which the rotor turns. Not like a distributor. I have not figured out why
          > yet. The reduction gearing I assume.
          > Maybe by Sunday evening I will have it going better. Got about 3000 rpms
          so
          > far - using a big car muffler.
          > Tom
          >
          >
          >
          > To unsubscribe from this group, send an email to:
          > AirVW-unsubscribe@yahoogroups.com
          >
          >
          >
          > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
          >
          >
        • Tom Cummings
          Hello Volksfolkes! I have made a little more progress on the never ending saga of the 1200 VW conversion. After running it a few hours with a distributor
          Message 4 of 11 , Jun 1, 2002
            Hello Volksfolkes!
            I have made a little more progress on the never ending saga of the 1200 VW
            conversion.
            After running it a few hours with a distributor system and a stock downdraft
            VW carb, I changed over today to a Fairbanks/Morse magneto. Keeping the
            downdraft carb for now reduces the variables at this stage.
            Well it runs. And I am learning more about mags as I go along. I did make my
            adjustment slots in the mounting plate a little bit off but I came pretty
            close for a beginner. I could only adjust the timing to 27 degrees BTDC
            instead of 25, so tomorrow I will have to remove the mag and file the
            plate's slots a little bit more. I would have expected the engine to ping at
            the 32 degrees BTDC at which it first fired, but it didn't. And I didn't
            understand why. As I continued to retard the mag several times and restart
            the engine, I got as close to 25 degrees BTDC as I could. But it is up and
            running with the mag as I had hoped. After I adjust for a few more degrees,
            I plan to install an updraft carburetor. Again, changing one variable at a
            time.
            One thing about the mag that surprised me most was that to retard the
            timing, I had to rotate the mag's housing in the opposite direction than
            which the rotor turns. Not like a distributor. I have not figured out why
            yet. The reduction gearing I assume.
            Maybe by Sunday evening I will have it going better. Got about 3000 rpms so
            far - using a big car muffler.
            Tom
          • Tom Cummings
            Okay Hal, That sounds like good news. Perhaps I won t have to take the mag back off afterall. I didn t see a change in rpms when reducing from 32 Degrees BTDC
            Message 5 of 11 , Jun 2, 2002
              Okay Hal,
              That sounds like good news. Perhaps I won't have to take the mag back off
              afterall. I didn't see a change in rpms when reducing from 32 Degrees BTDC
              to 27 Degrees BTDC.
              Tom
              ----- Original Message -----
              From: "Harold Hadaller" <flyhal@...>
              To: <AirVW@yahoogroups.com>
              Sent: Saturday, June 01, 2002 7:27 PM
              Subject: Re: [AirVW] 1200 VW


              > There is nothing exactly magic about 25 degrees advance. Over the years
              it
              > was found to be a completely safe setting without fear of being too
              > advanced. However, very few engines are timed as retarded as this ans
              > generally run a few degrees advanced from this. It also gives more power.
              > In automobiles it is very easy to lug and engine as cause pinging and
              > detonation. It is impossible to put an aircraft engine under such a load.
              > The basic problem with the mag is that it is either in the retarded/start
              > mode or the full advance mode so at 1000 to 1500 rpm it is rather advanced
              > for a normal running engine. But we never operate our engines under 2500
              > rpm or so when under load. I would have a tendency to push the advance a
              > bit. The Continentals run 26-28 degree settings depending on the engine.
              >
              > Hal
              >
              >
              > ----- Original Message -----
              > From: "Tom Cummings" <tomlc@...>
              > To: "VW Airlist" <AirVW@yahoogroups.com>
              > Sent: Saturday, June 01, 2002 10:55 PM
              > Subject: [AirVW] 1200 VW
              >
              >
              > > Hello Volksfolkes!
              > > I have made a little more progress on the never ending saga of the 1200
              VW
              > > conversion.
              > > After running it a few hours with a distributor system and a stock
              > downdraft
              > > VW carb, I changed over today to a Fairbanks/Morse magneto. Keeping the
              > > downdraft carb for now reduces the variables at this stage.
              > > Well it runs. And I am learning more about mags as I go along. I did
              make
              > my
              > > adjustment slots in the mounting plate a little bit off but I came
              pretty
              > > close for a beginner. I could only adjust the timing to 27 degrees BTDC
              > > instead of 25, so tomorrow I will have to remove the mag and file the
              > > plate's slots a little bit more. I would have expected the engine to
              ping
              > at
              > > the 32 degrees BTDC at which it first fired, but it didn't. And I didn't
              > > understand why. As I continued to retard the mag several times and
              restart
              > > the engine, I got as close to 25 degrees BTDC as I could. But it is up
              and
              > > running with the mag as I had hoped. After I adjust for a few more
              > degrees,
              > > I plan to install an updraft carburetor. Again, changing one variable at
              a
              > > time.
              > > One thing about the mag that surprised me most was that to retard the
              > > timing, I had to rotate the mag's housing in the opposite direction than
              > > which the rotor turns. Not like a distributor. I have not figured out
              why
              > > yet. The reduction gearing I assume.
              > > Maybe by Sunday evening I will have it going better. Got about 3000 rpms
              > so
              > > far - using a big car muffler.
              > > Tom
              > >
              > >
              > >
              > > To unsubscribe from this group, send an email to:
              > > AirVW-unsubscribe@yahoogroups.com
              > >
              > >
              > >
              > > Your use of Yahoo! Groups is subject to
              http://docs.yahoo.com/info/terms/
              > >
              > >
              > >
              >
              >
              >
              > To unsubscribe from this group, send an email to:
              > AirVW-unsubscribe@yahoogroups.com
              >
              >
              >
              > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
              >
              >
            • Tom Cummings
              Hal, According to the metal tag on the mag housing I have a 15 degree lag coupler. That s what it implies according the magneto shop technician here. But I am
              Message 6 of 11 , Jun 2, 2002
                Hal,
                According to the metal tag on the mag housing I have a 15 degree lag
                coupler. That's what it implies according the magneto shop technician here.
                But I am not sure because it didn't behave that way on startup.
                I assumed I had 15 degree lag when installing the mag. I advanced the crank
                to 10 degrees BTDC and rotated the mag housing on the puck until the mag
                fired - while holding the housing against the mounting plate. Then I marked
                the plate for cutting the slots for the bolts. And I made an alignment mark
                to insure an accurate installation of the mag after the slots were cut. This
                was to allow the engine to start at 10 degrees BTDC and run at 25 BTDC. But
                that is not the way it turned out. I immediately checked the timing with a
                light and it indicated 32 degrees BTDC. If I have a 15 degree lag, and I did
                apply the 10 degrees advance at the crankshaft, then the engine started at
                17degrees BTDC ! Seems high to me. An electric starter was used and not the
                slightest kickback was observed. Retarding the running mode to 27 degrees
                BTDC implies the engine started at 12 degrees BTDC.
                I think that since the engine ran at 32 degrees BTDC and I had put 10
                degrees in the crank, then I must have a 22 degree lag coupler. After
                retarding to 27 degrees running, the engine now starts at 5 degrees BTDC. I
                don't know for know for sure but I will keep working on it.
                Tom
                ----- Original Message -----
                From: "Jack Lockamy" <jacklockamy@...>
                To: <AirVW@yahoogroups.com>
                Sent: Saturday, June 01, 2002 7:34 PM
                Subject: Re: [AirVW] 1200 VW


                > Hal,
                >
                > Not sure what mag/impulse coupler Tom is using but the Slick 4216 has a 25
                degree lag. So if you statically time the mag at 27 degrees BTDC, what you
                actually have is a mag that fires at 2 degrees BTDC. Not bad, but I would
                probably go to 32 degrees BTDC static (actually firing at 7 degrees BTDC).
                >
                > Jack
                > ----- Original Message -----
                > From: "Harold Hadaller" <flyhal@...>
                > To: <AirVW@yahoogroups.com>
                > Sent: Saturday, June 01, 2002 7:27 PM
                > Subject: Re: [AirVW] 1200 VW
                >
                >
                > > There is nothing exactly magic about 25 degrees advance. Over the years
                it
                > > was found to be a completely safe setting without fear of being too
                > > advanced. However, very few engines are timed as retarded as this ans
                > > generally run a few degrees advanced from this. It also gives more
                power.
                > > In automobiles it is very easy to lug and engine as cause pinging and
                > > detonation. It is impossible to put an aircraft engine under such a
                load.
                > > The basic problem with the mag is that it is either in the
                retarded/start
                > > mode or the full advance mode so at 1000 to 1500 rpm it is rather
                advanced
                > > for a normal running engine. But we never operate our engines under
                2500
                > > rpm or so when under load. I would have a tendency to push the advance
                a
                > > bit. The Continentals run 26-28 degree settings depending on the
                engine.
                > >
                > > Hal
                > >
                > >
                > > ----- Original Message -----
                > > From: "Tom Cummings" <tomlc@...>
                > > To: "VW Airlist" <AirVW@yahoogroups.com>
                > > Sent: Saturday, June 01, 2002 10:55 PM
                > > Subject: [AirVW] 1200 VW
                > >
                > >
                > > > Hello Volksfolkes!
                > > > I have made a little more progress on the never ending saga of the
                1200 VW
                > > > conversion.
                > > > After running it a few hours with a distributor system and a stock
                > > downdraft
                > > > VW carb, I changed over today to a Fairbanks/Morse magneto. Keeping
                the
                > > > downdraft carb for now reduces the variables at this stage.
                > > > Well it runs. And I am learning more about mags as I go along. I did
                make
                > > my
                > > > adjustment slots in the mounting plate a little bit off but I came
                pretty
                > > > close for a beginner. I could only adjust the timing to 27 degrees
                BTDC
                > > > instead of 25, so tomorrow I will have to remove the mag and file the
                > > > plate's slots a little bit more. I would have expected the engine to
                ping
                > > at
                > > > the 32 degrees BTDC at which it first fired, but it didn't. And I
                didn't
                > > > understand why. As I continued to retard the mag several times and
                restart
                > > > the engine, I got as close to 25 degrees BTDC as I could. But it is up
                and
                > > > running with the mag as I had hoped. After I adjust for a few more
                > > degrees,
                > > > I plan to install an updraft carburetor. Again, changing one variable
                at a
                > > > time.
                > > > One thing about the mag that surprised me most was that to retard the
                > > > timing, I had to rotate the mag's housing in the opposite direction
                than
                > > > which the rotor turns. Not like a distributor. I have not figured out
                why
                > > > yet. The reduction gearing I assume.
                > > > Maybe by Sunday evening I will have it going better. Got about 3000
                rpms
                > > so
                > > > far - using a big car muffler.
                > > > Tom
                > > >
                > > >
                > > >
                > > > To unsubscribe from this group, send an email to:
                > > > AirVW-unsubscribe@yahoogroups.com
                > > >
                > > >
                > > >
                > > > Your use of Yahoo! Groups is subject to
                http://docs.yahoo.com/info/terms/
                > > >
                > > >
                > > >
                > >
                > >
                > >
                > > To unsubscribe from this group, send an email to:
                > > AirVW-unsubscribe@yahoogroups.com
                > >
                > >
                > >
                > > Your use of Yahoo! Groups is subject to
                http://docs.yahoo.com/info/terms/
                > >
                > >
                > >
                >
                >
                >
                > To unsubscribe from this group, send an email to:
                > AirVW-unsubscribe@yahoogroups.com
                >
                >
                >
                > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                >
                >
              • Tom Cummings
                Hi Paul, After I thought about it more, I remember the mag s rotor turns the opposite direction than the crankshaft. Apparently, it is due to the 2 to 1
                Message 7 of 11 , Jun 2, 2002
                  Hi Paul,
                  After I thought about it more, I remember the mag's rotor turns the
                  opposite direction than the crankshaft. Apparently, it is due to the 2 to 1
                  reduction gear of the mag's drive system. And I was incorrectly using the
                  rotor direction as orientation instead of the crankshaft as you stated.
                  Thanks.
                  Tom
                  ----- Original Message -----
                  From: "Paul&Bridget" <bscdoghouse@...>
                  To: <AirVW@yahoogroups.com>
                  Sent: Saturday, June 01, 2002 7:57 PM
                  Subject: Re: [AirVW] 1200 VW


                  > Tom
                  > About your mag dilemma. Mags, at least the Slick and Bendix variety, are
                  > just like a distributor. On the back of a VW engine, if you turn the mag
                  > housing in the same
                  > direction as the crank rotates that will delay the timing. I don't think
                  the
                  > F-M mags
                  > are any different. So, I don't understand how it happens like you say. It
                  > may take
                  > a moment before the light bulb comes on.
                  >
                  > Paul
                  > ----- Original Message -----
                  > From: "Tom Cummings" <tomlc@...>
                  > To: "VW Airlist" <AirVW@yahoogroups.com>
                  > Sent: Saturday, June 01, 2002 11:55 PM
                  > Subject: [AirVW] 1200 VW
                  >
                  >
                  > > Hello Volksfolkes!
                  > > I have made a little more progress on the never ending saga of the 1200
                  VW
                  > > conversion.
                  > > After running it a few hours with a distributor system and a stock
                  > downdraft
                  > > VW carb, I changed over today to a Fairbanks/Morse magneto. Keeping the
                  > > downdraft carb for now reduces the variables at this stage.
                  > > Well it runs. And I am learning more about mags as I go along. I did
                  make
                  > my
                  > > adjustment slots in the mounting plate a little bit off but I came
                  pretty
                  > > close for a beginner. I could only adjust the timing to 27 degrees BTDC
                  > > instead of 25, so tomorrow I will have to remove the mag and file the
                  > > plate's slots a little bit more. I would have expected the engine to
                  ping
                  > at
                  > > the 32 degrees BTDC at which it first fired, but it didn't. And I didn't
                  > > understand why. As I continued to retard the mag several times and
                  restart
                  > > the engine, I got as close to 25 degrees BTDC as I could. But it is up
                  and
                  > > running with the mag as I had hoped. After I adjust for a few more
                  > degrees,
                  > > I plan to install an updraft carburetor. Again, changing one variable at
                  a
                  > > time.
                  > > One thing about the mag that surprised me most was that to retard the
                  > > timing, I had to rotate the mag's housing in the opposite direction than
                  > > which the rotor turns. Not like a distributor. I have not figured out
                  why
                  > > yet. The reduction gearing I assume.
                  > > Maybe by Sunday evening I will have it going better. Got about 3000 rpms
                  > so
                  > > far - using a big car muffler.
                  > > Tom
                  > >
                  > >
                  > >
                  > > To unsubscribe from this group, send an email to:
                  > > AirVW-unsubscribe@yahoogroups.com
                  > >
                  > >
                  > >
                  > > Your use of Yahoo! Groups is subject to
                  http://docs.yahoo.com/info/terms/
                  > >
                  > >
                  >
                  >
                  >
                  > To unsubscribe from this group, send an email to:
                  > AirVW-unsubscribe@yahoogroups.com
                  >
                  >
                  >
                  > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                  >
                  >
                • Harold Hadaller
                  20 degrees is probably the most standard coupler. The LAG that one needs with a magneto impulse coupling is dependent on the starter and the speed that the
                  Message 8 of 11 , Jun 2, 2002
                    20 degrees is probably the most standard coupler. The LAG that one needs
                    with a magneto impulse coupling is dependent on the starter and the speed
                    that the engine turns over with that starter. Some Cessna's with a 28 volt
                    system use a 5 degree lag coupling. If the Lag is incorrect for the engine
                    it will be hard to start. Engines like to start best when they are actually
                    fired around 20 degrees or so. If the engine spins fast and when one
                    figures the delays in the actual spark getting to the cylinder and exploding
                    the compressed gases one needs to fire late or with not to much lag angle.

                    It seems that you have done your experimenting now to know what you have and
                    this monkey can be laid to rest. Considering measurement tolerances you
                    most likely have a 20 degree Lag and that is about optimum for most engine
                    systems.

                    Hal

                    ----- Original Message -----
                    From: "Tom Cummings" <tomlc@...>
                    To: <AirVW@yahoogroups.com>
                    Sent: Sunday, June 02, 2002 3:18 AM
                    Subject: Re: [AirVW] 1200 VW


                    > Hal,
                    > According to the metal tag on the mag housing I have a 15 degree lag
                    > coupler. That's what it implies according the magneto shop technician
                    here.
                    > But I am not sure because it didn't behave that way on startup.
                    > I assumed I had 15 degree lag when installing the mag. I advanced the
                    crank
                    > to 10 degrees BTDC and rotated the mag housing on the puck until the mag
                    > fired - while holding the housing against the mounting plate. Then I
                    marked
                    > the plate for cutting the slots for the bolts. And I made an alignment
                    mark
                    > to insure an accurate installation of the mag after the slots were cut.
                    This
                    > was to allow the engine to start at 10 degrees BTDC and run at 25 BTDC.
                    But
                    > that is not the way it turned out. I immediately checked the timing with a
                    > light and it indicated 32 degrees BTDC. If I have a 15 degree lag, and I
                    did
                    > apply the 10 degrees advance at the crankshaft, then the engine started at
                    > 17degrees BTDC ! Seems high to me. An electric starter was used and not
                    the
                    > slightest kickback was observed. Retarding the running mode to 27 degrees
                    > BTDC implies the engine started at 12 degrees BTDC.
                    > I think that since the engine ran at 32 degrees BTDC and I had put 10
                    > degrees in the crank, then I must have a 22 degree lag coupler. After
                    > retarding to 27 degrees running, the engine now starts at 5 degrees BTDC.
                    I
                    > don't know for know for sure but I will keep working on it.
                    > Tom
                    > ----- Original Message -----
                    > From: "Jack Lockamy" <jacklockamy@...>
                    > To: <AirVW@yahoogroups.com>
                    > Sent: Saturday, June 01, 2002 7:34 PM
                    > Subject: Re: [AirVW] 1200 VW
                    >
                    >
                    > > Hal,
                    > >
                    > > Not sure what mag/impulse coupler Tom is using but the Slick 4216 has a
                    25
                    > degree lag. So if you statically time the mag at 27 degrees BTDC, what
                    you
                    > actually have is a mag that fires at 2 degrees BTDC. Not bad, but I would
                    > probably go to 32 degrees BTDC static (actually firing at 7 degrees BTDC).
                    > >
                    > > Jack
                    > > ----- Original Message -----
                    > > From: "Harold Hadaller" <flyhal@...>
                    > > To: <AirVW@yahoogroups.com>
                    > > Sent: Saturday, June 01, 2002 7:27 PM
                    > > Subject: Re: [AirVW] 1200 VW
                    > >
                    > >
                    > > > There is nothing exactly magic about 25 degrees advance. Over the
                    years
                    > it
                    > > > was found to be a completely safe setting without fear of being too
                    > > > advanced. However, very few engines are timed as retarded as this ans
                    > > > generally run a few degrees advanced from this. It also gives more
                    > power.
                    > > > In automobiles it is very easy to lug and engine as cause pinging and
                    > > > detonation. It is impossible to put an aircraft engine under such a
                    > load.
                    > > > The basic problem with the mag is that it is either in the
                    > retarded/start
                    > > > mode or the full advance mode so at 1000 to 1500 rpm it is rather
                    > advanced
                    > > > for a normal running engine. But we never operate our engines under
                    > 2500
                    > > > rpm or so when under load. I would have a tendency to push the
                    advance
                    > a
                    > > > bit. The Continentals run 26-28 degree settings depending on the
                    > engine.
                    > > >
                    > > > Hal
                    > > >
                    > > >
                    > > > ----- Original Message -----
                    > > > From: "Tom Cummings" <tomlc@...>
                    > > > To: "VW Airlist" <AirVW@yahoogroups.com>
                    > > > Sent: Saturday, June 01, 2002 10:55 PM
                    > > > Subject: [AirVW] 1200 VW
                    > > >
                    > > >
                    > > > > Hello Volksfolkes!
                    > > > > I have made a little more progress on the never ending saga of the
                    > 1200 VW
                    > > > > conversion.
                    > > > > After running it a few hours with a distributor system and a stock
                    > > > downdraft
                    > > > > VW carb, I changed over today to a Fairbanks/Morse magneto. Keeping
                    > the
                    > > > > downdraft carb for now reduces the variables at this stage.
                    > > > > Well it runs. And I am learning more about mags as I go along. I did
                    > make
                    > > > my
                    > > > > adjustment slots in the mounting plate a little bit off but I came
                    > pretty
                    > > > > close for a beginner. I could only adjust the timing to 27 degrees
                    > BTDC
                    > > > > instead of 25, so tomorrow I will have to remove the mag and file
                    the
                    > > > > plate's slots a little bit more. I would have expected the engine to
                    > ping
                    > > > at
                    > > > > the 32 degrees BTDC at which it first fired, but it didn't. And I
                    > didn't
                    > > > > understand why. As I continued to retard the mag several times and
                    > restart
                    > > > > the engine, I got as close to 25 degrees BTDC as I could. But it is
                    up
                    > and
                    > > > > running with the mag as I had hoped. After I adjust for a few more
                    > > > degrees,
                    > > > > I plan to install an updraft carburetor. Again, changing one
                    variable
                    > at a
                    > > > > time.
                    > > > > One thing about the mag that surprised me most was that to retard
                    the
                    > > > > timing, I had to rotate the mag's housing in the opposite direction
                    > than
                    > > > > which the rotor turns. Not like a distributor. I have not figured
                    out
                    > why
                    > > > > yet. The reduction gearing I assume.
                    > > > > Maybe by Sunday evening I will have it going better. Got about 3000
                    > rpms
                    > > > so
                    > > > > far - using a big car muffler.
                    > > > > Tom
                    > > > >
                    > > > >
                    > > > >
                    > > > > To unsubscribe from this group, send an email to:
                    > > > > AirVW-unsubscribe@yahoogroups.com
                    > > > >
                    > > > >
                    > > > >
                    > > > > Your use of Yahoo! Groups is subject to
                    > http://docs.yahoo.com/info/terms/
                    > > > >
                    > > > >
                    > > > >
                    > > >
                    > > >
                    > > >
                    > > > To unsubscribe from this group, send an email to:
                    > > > AirVW-unsubscribe@yahoogroups.com
                    > > >
                    > > >
                    > > >
                    > > > Your use of Yahoo! Groups is subject to
                    > http://docs.yahoo.com/info/terms/
                    > > >
                    > > >
                    > > >
                    > >
                    > >
                    > >
                    > > To unsubscribe from this group, send an email to:
                    > > AirVW-unsubscribe@yahoogroups.com
                    > >
                    > >
                    > >
                    > > Your use of Yahoo! Groups is subject to
                    http://docs.yahoo.com/info/terms/
                    > >
                    > >
                    >
                    >
                    >
                    > To unsubscribe from this group, send an email to:
                    > AirVW-unsubscribe@yahoogroups.com
                    >
                    >
                    >
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                    >
                    >
                    >
                  • Paul&Bridget
                    Tom Can you take a moment and give some specifics on your 1200VW? Or can I find them somewhere in the Group message archives? I would like to know:
                    Message 9 of 11 , Jun 2, 2002
                      Tom
                      Can you take a moment and give some specifics on your 1200VW? Or can I find
                      them
                      somewhere in the Group message archives? I would like to know:
                      bore,stroke,installed weight,type heads, compression ratio, and estimated
                      horsepower.
                      I am in the engine selection process and am trying to accumulate engine data
                      for comparison.

                      Paul
                      ----- Original Message -----
                      From: "Tom Cummings" <tomlc@...>
                      To: <AirVW@yahoogroups.com>
                      Sent: Sunday, June 02, 2002 4:29 AM
                      Subject: Re: [AirVW] 1200 VW


                      > Hi Paul,
                      > After I thought about it more, I remember the mag's rotor turns the
                      > opposite direction than the crankshaft. Apparently, it is due to the 2 to
                      1
                      > reduction gear of the mag's drive system. And I was incorrectly using the
                      > rotor direction as orientation instead of the crankshaft as you stated.
                      > Thanks.
                      > Tom
                      > ----- Original Message -----
                      > From: "Paul&Bridget" <bscdoghouse@...>
                      > To: <AirVW@yahoogroups.com>
                      > Sent: Saturday, June 01, 2002 7:57 PM
                      > Subject: Re: [AirVW] 1200 VW
                      >
                      >
                      > > Tom
                      > > About your mag dilemma. Mags, at least the Slick and Bendix variety, are
                      > > just like a distributor. On the back of a VW engine, if you turn the mag
                      > > housing in the same
                      > > direction as the crank rotates that will delay the timing. I don't think
                      > the
                      > > F-M mags
                      > > are any different. So, I don't understand how it happens like you say.
                      It
                      > > may take
                      > > a moment before the light bulb comes on.
                      > >
                      > > Paul
                      > > ----- Original Message -----
                      > > From: "Tom Cummings" <tomlc@...>
                      > > To: "VW Airlist" <AirVW@yahoogroups.com>
                      > > Sent: Saturday, June 01, 2002 11:55 PM
                      > > Subject: [AirVW] 1200 VW
                      > >
                      > >
                      > > > Hello Volksfolkes!
                      > > > I have made a little more progress on the never ending saga of the
                      1200
                      > VW
                      > > > conversion.
                      > > > After running it a few hours with a distributor system and a stock
                      > > downdraft
                      > > > VW carb, I changed over today to a Fairbanks/Morse magneto. Keeping
                      the
                      > > > downdraft carb for now reduces the variables at this stage.
                      > > > Well it runs. And I am learning more about mags as I go along. I did
                      > make
                      > > my
                      > > > adjustment slots in the mounting plate a little bit off but I came
                      > pretty
                      > > > close for a beginner. I could only adjust the timing to 27 degrees
                      BTDC
                      > > > instead of 25, so tomorrow I will have to remove the mag and file the
                      > > > plate's slots a little bit more. I would have expected the engine to
                      > ping
                      > > at
                      > > > the 32 degrees BTDC at which it first fired, but it didn't. And I
                      didn't
                      > > > understand why. As I continued to retard the mag several times and
                      > restart
                      > > > the engine, I got as close to 25 degrees BTDC as I could. But it is up
                      > and
                      > > > running with the mag as I had hoped. After I adjust for a few more
                      > > degrees,
                      > > > I plan to install an updraft carburetor. Again, changing one variable
                      at
                      > a
                      > > > time.
                      > > > One thing about the mag that surprised me most was that to retard the
                      > > > timing, I had to rotate the mag's housing in the opposite direction
                      than
                      > > > which the rotor turns. Not like a distributor. I have not figured out
                      > why
                      > > > yet. The reduction gearing I assume.
                      > > > Maybe by Sunday evening I will have it going better. Got about 3000
                      rpms
                      > > so
                      > > > far - using a big car muffler.
                      > > > Tom
                      > > >
                      > > >
                      > > >
                      > > > To unsubscribe from this group, send an email to:
                      > > > AirVW-unsubscribe@yahoogroups.com
                      > > >
                      > > >
                      > > >
                      > > > Your use of Yahoo! Groups is subject to
                      > http://docs.yahoo.com/info/terms/
                      > > >
                      > > >
                      > >
                      > >
                      > >
                      > > To unsubscribe from this group, send an email to:
                      > > AirVW-unsubscribe@yahoogroups.com
                      > >
                      > >
                      > >
                      > > Your use of Yahoo! Groups is subject to
                      http://docs.yahoo.com/info/terms/
                      > >
                      > >
                      >
                      >
                      >
                      > To unsubscribe from this group, send an email to:
                      > AirVW-unsubscribe@yahoogroups.com
                      >
                      >
                      >
                      > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                      >
                      >
                    • Tom Cummings
                      ... 1.Bore 83mm. I used the oversized slip in cylinders.This brought the displacement up to 1385ccs. The stroke is 64mm. 2.Installed weight not determine yet
                      Message 10 of 11 , Jun 2, 2002
                        Paul wrote:

                        > Tom
                        > I would like to know:
                        > bore,stroke,installed weight,type heads, compression ratio, and estimated
                        > horsepower.
                        1.Bore 83mm. I used the oversized slip in cylinders.This brought the
                        displacement up to 1385ccs. The stroke is 64mm.
                        2.Installed weight not determine yet because I am trying to develope a final
                        configuration with an updraft or sidedraft carb and eventually remove the
                        starter, flywheel, muffler,and battery systems and stay with the magneto. I
                        plan on powering the HAPI VW triad cluster aircraft instuments with a
                        transducer that connects the instruments to the magneto's P lead. The stock
                        longblock without stock flywheel and exhaust system but including a stock
                        intake manifold weighed 117 pounds. The bored out cylinders weigh
                        considerably less than the thick walled stock 77mm cylinders. I am retaining
                        the full flow oil system to utilize the benefits of the remote oil filter
                        and cooler. I will weight the engine just before installing it on the
                        airframe. (Supercat).
                        3.Stock 1200 heads are used. They have 1 to 1 ratio rocker arms and I will
                        later attempt to install the 1.1 to 1 ratio rockers from a 1600 VW to test
                        for any improvement. I was advised not to use the 1.25 to 1 rockers on the
                        1200 VW heads. The 1200 valves are smaller in diameter than 1600 valves. I
                        don't have the valve sizes at hand right now. They are sometimes printed in
                        catalogs. The 1600 heads would not quite provide enough sealing surfaces
                        against the cylinders. Almost, but not worth the risk. Sure would have liked
                        to have tried them if they would have fit better.
                        4.Compression ratio is 7.5 to 1 after installing cylinder base shims to
                        reduce the ratio from 8.0. This was done to use lower octane fuel and was
                        supposed to allow for increase ignition advance.( the aftermarket 83 cc
                        cylinders raised the CR to 8.0.) And there was less than .040 inch deck
                        height with 83mm P/Cs so I felt the shims were necessary. The engine would
                        have more power at 8.0 but I was building for longivity. The stock 77cc
                        cylinder CR ratio was 7.0.
                        5.My horsepower is not known. I don't know the increase from my
                        modifications but I assume it is more than the stock configuration.The stock
                        1200 was rated 41.5 hp at 3900 rpms for the 1965 sedan. This was obtained
                        from a Glenn's Auto Repair Manual 34th Edition, printed in 1971. I have been
                        told from other sources that it was only 36 hp. My Supercat is only supposed
                        to fly at 60 mph. I am trying to build a lightweight four cylinder engine
                        which is simpler for me to do than making a half VW.

                        There are some archived posts on this project. They were usually shown as
                        "1200 VW" .
                        I made a few pics at http://www.geocities.com/tomlc1/volks2.html to show the
                        teststand setup using a quick and dirty cooling system and
                        http://www.geocities.com/tomlc1/Volks.html shows a few construction pics.
                        They take a while to load.
                        Tom
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