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Thread: MSD 6AL box question

  1. #11
    Registered Member chasracer's Avatar
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    Sent you a PM.

  2. #12
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    Rick, I appreciate your help. In the scenario I gave I did indeed have the vacuum advance disconnected. With the amount of timing advance it has I am baffled as to why the engine doesn't *buck* when trying to start it and why it isn't pinging. Just now I rechecked the timing with the vacuum disconnected and plugged (although I don't see any need to plug the vacuum hose unless your engine won't run with the vacuum leak). The initial is 22° advanced and the total is a whopping 50°. Two different timing lights both give the same reading on the balancer on the tape, not using dial back. That centrifugal advance shocked the shit out of me, but it ran great and didn't knock or ping. After some thinking, I believe the centrifugal is so high because I borrowed the advance stop bushing for my other distributor and forgot to put it back on this one. I'll be back in a few days.
    Tony

    1955 Bel Air Sport Coupe

  3. #13
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    Doesn’t that 50 degree-22 degrees initial=28 divide by 2 for distributor speed =14 degrees put the rotor way off position with the distributor contacts? Unless this is total electronic fixed distributor (which I assume it is not) doing phase compensation there is big spark gap.

  4. #14
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    Rotor phasing is the least of problems with what's been described. 22° initial advance is WAY too much for almost any engine, especially a BBC, unless running fixed timing. I suspect it's not being checked properly either (vacuum advance may be connected) because the engine should have hot start and pinging problems with 22° advance. Another possible situation could be that the timing mark is off, and until it is, everything seen or reported is just garbage as far as the numbers.

    But, if the engine could really run that timing successfully, rotor phasing might be off - but maybe not enough to be a huge problem.

  5. #15
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    Rick, he did say the vacuum was plugged. But as you say 22 is too much initial. The only condition that could work is on drag strip without power adders. But the all in shouldn’t be 50 degrees. Your suggestion the timing mark must be off position is most plausible.

    14 degrees on a small diameter distributor is a rotor displacement of about 3/8”.
    Last edited by Gmvette; 12-18-2018 at 09:31 AM.

  6. #16
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    Didn't realize this was about me. I've had the strangest things go on with timing and this motor. Before the rebuild it was reading off the charts, as if the light was clamped on the wrong wire. Two of my lights and a third at a garage did this. Then suddenly it started reading correctly. The balancer key is in line with the 0° mark. Since then everything timing wise has been changed and still I sometimes get crazy readings. If I increase it until it slows down then back it off again, how far back should I go?

  7. #17
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    Quote Originally Posted by 55 Tony View Post
    Didn't realize this was about me. I've had the strangest things go on with timing and this motor. Before the rebuild it was reading off the charts, as if the light was clamped on the wrong wire. Two of my lights and a third at a garage did this. Then suddenly it started reading correctly. The balancer key is in line with the 0° mark. Since then everything timing wise has been changed and still I sometimes get crazy readings. If I increase it until it slows down then back it off again, how far back should I go?

    Something had to change for it to start reading correctly maybe the pick up is screwed up. If it is it will cause everything to be out of wack even the rotor phase to the cap. Electronic stuff is sometimes difficult to trace out.
    try another module or go to a points set up. Do switching when it is screwed up, one piece at a time. i put my money on the magnetic pick up. I had a similar problem with Pertronix piece of crap, put the points back in, ........problem solved.

    Run it without the MSD box no telling if something weird is going on there.
    Last edited by Gmvette; 01-22-2019 at 01:38 PM.

  8. #18
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    Quote Originally Posted by Gmvette View Post
    Something had to change for it to start reading correctly maybe the pick up is screwed up. If it is it will cause everything to be out of wack even the rotor phase to the cap. Electronic stuff is sometimes difficult to trace out.
    try another module or go to a points set up. Do switching when it is screwed up, one piece at a time. i put my money on the magnetic pick up. I had a similar problem with Pertronix piece of crap, put the points back in, ........problem solved.

    Run it without the MSD box no telling if something weird is going on there.
    First time it did it was with a very old msd distributor with no 6AL box. If it were actually firing light the timing light showed, no way could it have run. Did it with a different msd distributor, and a different balancer. Right now it's running the 6Al box and it's working properly ... that is if I hold the clamp on pickup @ 90° to the rest of the wires. I think it's possessed.
    Tony

    1955 Bel Air Sport Coupe

  9. #19
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    Tony, I don’t follow what you mean by “that is if I hold the clamp on pickup @ 90° to the rest of the wires. I think it's possessed.”

    Are any of the wires in bad shape?, grounding out?

    Generally the wires coming out of the distributor “they” recommend twisting them together so nothing is like a single strand. Something about RF interference. Worth a try.

  10. #20
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    Quote Originally Posted by Gmvette View Post
    Tony, I don’t follow what you mean by “that is if I hold the clamp on pickup @ 90° to the rest of the wires. I think it's possessed.”

    Are any of the wires in bad shape?, grounding out?

    Generally the wires coming out of the distributor “they” recommend twisting them together so nothing is like a single strand. Something about RF interference. Worth a try.
    I've heard a lot of timing lights don't like msd 6AL boxes. This is what I do to make it work. This I believe is just good for the msd box wackyness, nothing to do with the other weird readings I sometimes get. Wires are good. I know they say #5 and #7 wires should not run touching each other parallell, if they need to cross, try to make it at a right angle.
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    Last edited by 55 Tony; 01-24-2019 at 05:07 PM.
    Tony

    1955 Bel Air Sport Coupe

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