SM Ignition Timing
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  1. #1
    Fellow Frogger!
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    Default SM Ignition Timing

    I am trying to help a mate of mine fix the Ign timing on his SM.Unfortuately,while in a delusional state, he removed the Dissy and plug leads.Now to get them back in the right place!I think this would be easy with the original dissy ,however he has a Stinger electronic dissy so firstly, how to identify when it is sparking.2 How to identify No 1 plug lead.Unlike the original this cap has equally spaced terminals.Any help appreciated.
    Woody

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  2. #2
    Fellow Frogger! marc61's Avatar
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    TDC for No 1 is marked PMH on the flywheel which should help get No 1 lead connected to the right terminal in the cap, but take the plug out and check it's on the compression stroke to be sure.

    Am not familiar with that distributor, but if it's got a single coil I'd guess the lead connections would follow the firing order sequence 162534; if it's the normal two coil firing each bank then the connections to the cap would be as standard and shown in the manual.
    Cheers, Marc.

    1987 CX GTi T2 Maikonics
    1972 SM 2.7 carb
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  3. #3
    1000+ Posts Ken W's Avatar
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    Woody,

    Marc's advice is sound. I'm sure you will work it out. Here are some timing instructions for you.


    Cheers, Ken
    Attached Thumbnails Attached Thumbnails SM Ignition Timing-sm-aust-servicing-tuning-specs.jpg  

  4. #4
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    Thanks Marc, I can do that with some difficulty as is is an auto ,doing that I can align the Rotor with any terminal and call it no 1,that gives me a 50pc chance of it being OK due to the uneven gaps between sparks. (45degrees and 75d)
    Woody

  5. #5
    1000+ Posts Ken W's Avatar
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    Woody,

    I know it is from a Bosch injection manual but does this diagram help with the ignition timing?

    I think the second ignition point for cylinder 6 is wrong - it should be at 90 degrees not 120.

    Cheers, Ken
    Attached Thumbnails Attached Thumbnails SM Ignition Timing-injection-ignition-timing.jpg  
    Last edited by Ken W; 29th August 2017 at 11:24 PM. Reason: Add possible error

  6. #6
    1000+ Posts Ken W's Avatar
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    So after studying the diagram, perhaps start off with number 1 with a 45 distributor degrees - 90 crank degrees to cylinder 6, then a 75 distributor degrees - 150 crankshaft degrees to cylinder 2 and so on.

    I guess the distributor gear will fit in to the layshaft gear where the HT leads stretch to all the cylinders most easily.

    I rotated the crank by hand and checked out all the timing marks through the timing window on the clutch bellhousing so I knew what I was looking for with the timing light.

    Get the rotor pointing to the lead to cylinder 1 with the crank on PMH on the firing stroke and it should start. Then get the timing light going on Cylinder 1 and rotate distributor to get it firing on the 30 degree mark on crank at 2000 rpm and lock into place.

    Well that is the theory. Let us know how you go in practice.

    Cheers, Ken

  7. #7
    Fellow Frogger! citroenthusiast's Avatar
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    Is the Stinger dissy an optical, Hall-effect, or magnetic? If it is optical, you can usually look at the spacing of the shutters to figure out which are the 1-2-3 versus the 6-5-4 trigger points, same with the teeth on a Hall-effect trigger. If there are magnets embedded in a plastic ring, then you can usually find them with a bit of steel, like a paper clip, then mark the ring with a sharpie or white out. Of course finding TDC is relatively easy if you remove the plug and put your thumb over the hole as you turn the engine. The air pressure will push your thumb off as you approach the end of the compression stroke.
    Cheers,
    John T.

    61DS19 LHM BVH (son's); 67DS21 BVH; 71DS21 BVH; 73SM 3.0; 73SM EFI (Megasquirt); 73SM 3.0 (other son's)

  8. #8
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    Thanks for that.It appears to be magnetic, not sure if its Hall effect. There are no embeded magnets.Looking carefully at the spaceings of the poles I have worked out which are the long and short gaps and marked the Dissy cap .My guess is that the spark occurs when the points of the magnetic poles come closest.Assuming that is so I can now do the timing !!
    Woody

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