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    Lumenition static timing

    It's me again...

    First start-up of my rebuilt engine the other day, then moved the dizzy to the position where it ran sweetest - which happened to be at the clockwise extremity of the adjustment. With the objective of setting the timing properly, today I dug out the following from an old thread on the Forum -

    STATIC IGNITION TIMING
    Use a voltmeter or 12V bulb not exceeding 6W wired between the ignition
    coil negative terminal and earth (see illustration 4). Turn engine and align
    timing marks making sure the rotor tip is pointing to the HT pick-up
    segment in the distributor cap of the recommended firing plug, normally No
    1
    With distributor cap removed the leading edge of the chopper blade should
    be 2/3rds across the lensed units in the direction of rotation. Slacken
    distributor clamp bolt and very slightly turn distributor in direction of rotor
    rotation This is just enough to bring the chopper blade before the point of
    passing between the lensed units. Switch on ignition taking care not to
    crank the engine
    Very gently return the distributor against the direction of rotation to the exact point that the voltmeter reads around 12V or the test
    bulb lights If you overshoot return far enough to start again otherwise you will time on backlash. When correct, tighten clamp,
    remove voltmeter/bulb, replace cap and the engine will be ready for starting. It should be noted that the coil is switched off (spark
    occurs) when the leading edge of the chopper blade is 2/3rds through the lensed units



    With the timing mark at 12deg BTDC, and rotor pointing to HT pickup #2, I am not quite able to achieve the position where I see12V on the meter as per above. If I take the dizzy fixing bolts completely out, I am able to move it just a little more and achieve the 12V reading. I thought I needed to move the distributor by 1 x tooth on the drive gear, but if I do this, of course the rotor arm ends up pointing in the wrong direction.

    I feel like I'm missing something fundamental - would be grateful for any advice. Thanks - Dave.

    IMG_4793.jpg

    #2
    Tooth out on the jackshaft sprocket. Did you line up the mark as per the ROM ?.

    Comment


      #3
      It’s a guide - do what you need to in order to make it work. My rotor points further to the right than yours at initial set up and the engine runs sweet
      Paul - 3 projects, 1 breaker - garage built and housing 2 white Stags. One runs, one doesn't

      Comment


        #4
        Dave.
        It would be more accurate to set it up with a strobe light if you can borrow one. (attach it to No 2 /NSF plug lead).
        12 degrees BTDC is the third pointer to the right on the vernier gauge next to the crankshaft damper/pulley. Put a spot of Tippex on that, and some to highlight the groove on the pulley. Leave the distributor just loose enough to rotate it, and with the engine ticking over, turn the distributor till the white marks appear opposite each other. Then you will have the timing spot on. Re-tighten the distributor!
        It is not necessary to disconnect the vacuum pipe to the distributor while doing this.
        Mike.

        Comment


          #5
          Thanks guys - I was beginning to suspect that it must be alignment of the jackshaft sprocket being out. Per Paul's suggestion, as long as the correct firing order is maintained, I guess it doesn't matter which contact on the distributor cap is connected to cylinder #2? The engine was rebuilt by others, and here's a thing - when I got the engine back all of the ancillaries which they had removed (carbs, distributor, alternator, starter etc.) were in a box for me to re-install. When I came to fit the dizzy cap I was puzzled as to why the HT leads didn't seem to be in the right places; i.e. wrong lengths to reach the cylinders, so I pulled them all off and started again. I'd expected that the cap and leads had remained together while the engine was being rebuilt, so why would the leads not be in the correct positions? It all suggests that the jackshaft sprocket was out prior to the rebuild, and the workshop put it back together as they had found it - though these guys have a reputation for their work on Stag engines so I would have expected them to go by the book(?)

          I do intend to set it with a strobe, but was attempting to initially set it static when I encountered this; as it is currently, the most advanced I can set to is only a few degrees BTDC. I did have a strobe when I owned my last Stag, but that was nigh on 40 years ago and I'm struggling to put my hands on it....

          Cheers - Dave

          Comment


            #6
            If you move the dizzy one tooth it is necessary to move the plug leads around one place to get the rotor arm to point at the terminal in the dizzy cap.

            looks like this had already been done and would put the dizzy clamp bolts in the middle of the slot. Have had to do this myself before I realised the mark on the jackshaft was there for a reason!

            Neil
            Neil
            TV8, efi, fast road cams and home built manifolds. 246bhp 220lbft torque

            Comment


              #7
              I thought I had gone by the book on that jack shaft but still had to move it a tooth and move the leads accordingly. All is well..

              Who knows, maybe the new jack shaft sprockets supplied nowadays are a bit off.. it cannot have been me
              Last edited by trunt; 26 July 2021, 00:33.
              Terry Hunt, Wilmington Delaware

              www.terryhunt.co.uk

              Comment


                #8
                All done - thanks for the support, guys.

                Now where is that strobe…?

                Comment

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