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Cutting a slot in the rear of the camshaft journal

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  • Cutting a slot in the rear of the camshaft journal

    So for this project. The car had a distributorless ignition from electromotive. I need to put a distributor back on for vintage sports car racing. The VW style distributors are usually used but I don't like the drive adapter as made in the first picture. It pushes the distributor way out and it doesn't look all that efficient. To stop it from twisting there is a tig tack on the back in a few spots. Basically if I have a straight slot offset from center, that fits the drive in the distributor it's good to go. So not complicated on first look. I have a few old cams that have no value. They are cores that get welded up and reground, so before any of that gets done they are basically worth nothing. It doesn't doesn't hurt if one gets scrapped in the learning process.



    My idea is to cut the fuel pump lobe off since that is doing nothing on this car. Then slot the face of the journal. It cant go across the complete face as the bearing surface would be affected. So the slot has to be carved out of the rear. The removal of the lobe seems easy enough in the lathe. Its the carving out of the slot I am having trouble with figuring out the best way to fixture. I have an old bridgeport mill and lathe. I just use them for odds and ends. This is one of those. The idea is to drive the distributor off the end of the cam getting it out of the way of the induction. This is a 80s hydroplane engine that sort of gave me the idea. an alternative is to cut the fuel pump eccentric lobe off and tig weld a new stub that's centered and slotted in its place. Just did not know how well welding on cast steel would go and cutting seems easier than adding parts and it ends up more compact also.

    Last edited by donf; 09-12-2020, 01:45 PM.

  • #2
    Just hang it off the side of the Bridgeport table, pointing towards the floor
    and cut your slot with a carbide end mill. Seems like a simple job.

    -D
    DZER

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    • #3
      ^this. Just move your bridge port vice to the back t slot off to the side of the knee, rotate the head ram over. Move the vice jaws to one side so they over hang the vice.

      Comment


      • #4
        Originally posted by no704 View Post
        ^this. Just move your bridge port vice to the back t slot off to the side of the knee, rotate the head ram over. Move the vice jaws to one side so they over hang the vice.
        Wow that is really complicated.
        I was thinking to use a large V-block, clamp it to the table
        with the V hanging off the edge. Then clamp the cam in
        the V block.

        Or just set the cam in the T slot of the table
        clamp it to the table, and use a slitting saw
        to cut the slot.

        -D
        DZER

        Comment


        • #5
          Cut a key seat across flush end of cam . Not out the sides.
          drill and tap end of cam. Make a drive bushing with keyslot on cam end, drill hole thru the center.
          use 2 pces of key stock and bolt on..
          WOULD THAT WORK .?

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          • #6
            Wait stop ... does the slot have to be registered with the cam for proper distributor timing?

            Joe B

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            • #7
              Originally posted by JoeCB View Post
              Wait stop ... does the slot have to be registered with the cam for proper distributor timing?

              Joe B
              You can arrange the wires in any clocking you need, I would suspect.

              -D
              DZER

              Comment


              • #8
                Originally posted by Doozer View Post

                Wow that is really complicated.
                I was thinking to use a large V-block, clamp it to the table
                with the V hanging off the edge. Then clamp the cam in
                the V block.

                Or just set the cam in the T slot of the table
                clamp it to the table, and use a slitting saw
                to cut the slot.

                -D
                not that bad, maybe a ten minute set up with a beer break.
                best thing would be to have a 90deg head.

                Comment


                • #9
                  Originally posted by JoeCB View Post
                  Wait stop ... does the slot have to be registered with the cam for proper distributor timing?

                  Joe B
                  A little but not that hard to hit. I could pick any terminal for number 1. I figured straight across with the cam at TDC would get me there. Thanks to all for the advice.

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                  • #10
                    Originally posted by no704 View Post
                    not that bad, maybe a ten minute set up with a beer break.
                    best thing would be to have a 90deg head.
                    Bridgeport head tilts 90 degs.
                    “I know lots of people who are educated far beyond their intelligence”

                    Lewis Grizzard

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                    • #11
                      The type of distributor used on the older British cars can be rotated and locked in any position, so as long as there is clearance for that, it wouldn't matter what angle the slot was. With solid carbide end cutting mills, the slot could be plunged without interfering with the bearing journal surface, therefore eliminating the welded on end.

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                      • #12
                        Originally posted by Dave C View Post

                        Bridgeport head tilts 90 degs.
                        It's all in how you work the head.

                        -D
                        DZER

                        Comment


                        • #13
                          Originally posted by Doozer View Post

                          It's all in how you work the head.

                          -D
                          Yup
                          “I know lots of people who are educated far beyond their intelligence”

                          Lewis Grizzard

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                          • #14
                            Woodruff key slot would maintain both stength and bearing surface.
                            Helder Ferreira
                            Setubal, Portugal

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                            • #15
                              I am not sure a key slot would fit the profile of the distributor drive. It could be reprofiled but for ease I am trying to modify as few parts as possible.

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