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Help with '60 tune up specs

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  • David D.
    Expired
    • January 1, 2005
    • 416
    #1

    Help with '60 tune up specs

    Trying to figure out what some specs for a '60 283 w/single WCFB carb should be.....We seem to have about 3 different numbers and need your expert help in determining what is correct.

    We already have the Lars documents but we also have Corvette Service guide and other info, so that is where there is confusion. Would like real numbers if possible.

    1) What is timing supposed to be at idle? 4 BTDC or 18 BTDC ?
    2) What is Vacuum supposed to read at idle? 18-20" or <6"
    3) What should RPM's be? 475 rpm or 700 rpm
    with or with out vacuum advance connected?
    4) At what rpm or HG vacuum should vacuum can kick in?
    5) What rpm or HG vacuum should full in be at?

    Any other numbers that we should pay attention to would be appreciated.

    FYI-Current idle readings currently around 700rpm at 18 BTDC but vacuum around 6" flucuating badly.

    Thanks,
    David
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    • Duke W.
      Beyond Control Poster
      • January 1, 1993
      • 15610
      #2
      Re: Help with '60 tune up specs

      A base 283 should idle at about 500 in neutral (manual trans) and pull 18-19" Hg manifold vacuum in normal configuration, which means full time vacuum advance with the VAC connected. So is it a manual or PG?

      If your idle is 700 @ 6" in neutral then it either has a serious vacuum leak or some high overlap aftermarket cam, in which case the OE "tuneup" specs are irrelevent.

      Duke
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        • David D.
          Expired
          • January 1, 2005
          • 416
          #3
          Re: Help with '60 tune up specs

          Originally posted by Duke Williams (22045)
          A base 283 should idle at about 500 in neutral (manual trans) and pull 18-19" Hg manifold vacuum in normal configuration, which means full time vacuum advance with the VAC connected. So is it a manual or PG?

          If your idle is 700 @ 6" in neutral then it either has a serious vacuum leak or some high overlap aftermarket cam, in which case the OE "tuneup" specs are irrelevent.

          Duke
          Duke,
          It is a manual. We are running very low vacuum at idle and it is flucuating badly below 10" which we have set to 700, because it won't run down around 500 rpm......
          We connected as full configuration and now we have around 13" hg at 700rpms
          What should initial timing be set at? 4 degree BTDC or 18 degree BTDC which is where we are now?

          What would be the affects if distributor was off by a tooth?

          David
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            • Duke W.
              Beyond Control Poster
              • January 1, 1993
              • 15610
              #4
              Re: Help with '60 tune up specs

              You probably have issues that go way beyond "tuneup specs". Distributor installation is likely not the cause, but do some archive searching as distributor installation has been discussed a zillion times including a very good photograph (by John Hinckley) of proper wire indexing and distributor orientation when everthing is assembled and installed correctly.

              Duke
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                • David D.
                  Expired
                  • January 1, 2005
                  • 416
                  #5
                  Re: Help with '60 tune up specs

                  Would really like to know what timing should be at idle? And should this be with Vacuum can in or out to set intial setting?

                  According to the Tune Up Specs it says 4 degree BTDC

                  According to Lars it says set initial timing to 18 degrees BTDC

                  We have a dial back timing light and we have it set at 18 degrees.

                  Not sure this is making sense but we are really confused....to say the least.

                  Like I said, the vacuum at 700 rpm with vacuum can in is 13"HG

                  Thanks,
                  David
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                    • David D.
                      Expired
                      • January 1, 2005
                      • 416
                      #6
                      Re: Help with '60 tune up specs

                      OK update:

                      Did a compression check and found out why we have been all over the place and confused.....

                      Cylinder
                      1 - 20 psi
                      2 - ~ 130 psi
                      3 - ~ 130 psi
                      4 - ~ 120 psi
                      5 - ~ 130 psi
                      6 - 0 psi
                      7 - ~ 130 psi
                      8 - ~ 120 psi

                      Squirt some Marvels into #1 & # 6 and re-read (No change) not sure it's thick enough to get a good reading. Pulled valve covers and didn't notice anything obvious so it looks like we'll be tearing into it some more over the next few days....

                      Any suggestions/comments/recommendations would be appreaciated.

                      Thanks,
                      David
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                        • Robert H.
                          Expired
                          • December 1, 1997
                          • 1
                          #7
                          Re: Help with '60 tune up specs

                          Originally posted by David Duell (43184)
                          OK update:

                          Did a compression check and found out why we have been all over the place and confused.....

                          Cylinder
                          1 - 20 psi
                          2 - ~ 130 psi
                          3 - ~ 130 psi
                          4 - ~ 120 psi
                          5 - ~ 130 psi
                          6 - 0 psi
                          7 - ~ 130 psi
                          8 - ~ 120 psi

                          Squirt some Marvels into #1 & # 6 and re-read (No change) not sure it's thick enough to get a good reading. Pulled valve covers and didn't notice anything obvious so it looks like we'll be tearing into it some more over the next few days....

                          Any suggestions/comments/recommendations would be appreaciated.

                          Thanks,
                          David
                          David, good to see you guys got through the compression check, although the numbers on #1 and #6 are awful.
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