Struggling With Understanding Engine Timing Concepts

Discussion in 'Engine Topic' started by Bandit723, Jul 24, 2017.

  1. Bandit723

    Bandit723 Veteran Member

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    Oct 1, 2016
    Waupaca WI
    still clear as mud sorry....if i advance the dist to 27 at startup i still would only be at 28 at all in so what is the total?
     
  2. biker

    biker Veteran Member

    Your mechanical advanc mechanism is still working. It will provide X amount of degrees of advance all on its own as revs increase. With yours, it sounds like it will stop advancing by 2800 rpm, but you dont know how much that is. If that mechanism provides 22 degrees of advance, then you add that to whatever initial timing you have dialed in.

    I think I'm understanding you now. When you set your light to 28 degrees, rev to say 3000 rpm and your balancer indicates 0 degrees at the pointer, then your total timing is now 28 degrees.

    When you drop to idle and measure your initial timing, it just falls wherever it falls as a consequence of where you set total timing. If you measure your inital timing and it says 10 degrees, then you know that your distributor advance mechanism has 18 degrees of avance built in. (28 degrees total, minus the 10 initial). Hope that helps.
     
  3. Bandit723

    Bandit723 Veteran Member

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    Oct 1, 2016
    Waupaca WI
    Getting closer might be just the way the dist works that is throwing me off. So yes when i set the timing light to 28 degrees and set the timing at 3000 rpm's to indicate 0 on the balancer then i am truly 28 degrees advanced Total regardless of the idle timing?.

    so in the example I check the idle at 20 set on the timing light and shows 0 on the balancer so in this case i am sitting at 20 degrees advanced idle and check the all in at 3000 rpms so set the timing light to 28 and shows 0 on the balancer so the would give me 8 degrees of mechanical advance built into the dist? so 28 all in - 20 idle = 8 mechanical advance but the total timing is still 28 degrees or is the dist more advanced so 28 all in + 20 idle = total advance of 48?

    I guess what also throws me off is that the Mallory dist has the ability to adjust the advance stops to limit the centrifugal advance so i would think that would mean the amount of mechanical advance built in but the all in "3000" rpm advance does not go over 28 degrees regardless of where the idle timing is set. I will test this one out tonight just in case i am just nuts here "sanity check"
     
  4. Coadster32

    Coadster32 Veteran Member Lifetime Gold Member

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    Oct 2, 2013
    Milford,CT
    How about a different view on this. Set your timing light to zero, and fire the car up.
    At idle, what you see is your static timing. This can be adjusted by rotating the distributor cap.
    Rev it up to 2800-3000. What you see now is your total timing.
    The difference between the two is what your mechanical advance in your distributor, (weights and springs), is set at.
    It is that simple, but really easy to over-complicate. Some people don't use "dial-back" lights just for this reason.
    Vacumm advance is something you don't have, so no need to get into that.
    Now where you're current engine setup needs to be at...I honestly can't help you much with that. Hope this helps.
     
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  5. Bandit723

    Bandit723 Veteran Member

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    Oct 1, 2016
    Waupaca WI
    Thanks Coadster....Yes I am over thinking this or more questioning what i thought to be right "been reading too many internet posts". So at this point i am satisfied that the dist is set to 28 degrees advanced regardless of what my static timing is set at even if i could start this thing at 10 BTDC i would still come out at 28 advanced and this is total advance no magic fuzzy math to push it up.

    So again thanks needed to hear the total is what it shows on the timing light. At this point i can move on and do some adjusting.
     
    Coadster32 likes this.
  6. biker

    biker Veteran Member

    Yep, sounds like you got it now. Total timing is what matters. I'm actually struggling with mine too. I need 30 degrees total, but my distributor has 22 built into the advance mechanism, meaning my initial will end up at 8 which is way too low for the overlap I have to run well at idle. So, I have to cut back my mechanical so I can bump my initial and still end up at 30-32 total. Or, I can hook my vacuum advance to full vacuum and it may help me out at idle.
     
  7. Rdobbs1977

    Rdobbs1977 Huge Guns N Roses Fan

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    Dec 1, 2014
    Nashville
    biker, why do you need to be set on 30-32 all in? the only post i've read on this thread is yours so if you mentioned some other specs or info, i can go back and check. First thing to know about engine timing is to give your motor what it likes, not what you think it should like. IE you can set base by ear as they say based upon motor response, etc. or you can put a vacuum gauge on their to get that perfect base number. As to total, most like it around 34-36. So with that number, you'd not have any problems or need to look into buying new weights. I run a pro billet dizzy on my drag car that comes with bushings so if a guy really wants to tinker with timing, he's got all the bushings he needs to do it....
     
  8. CasperCasper

    CasperCasper Veteran Member

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    Aug 11, 2015
    It seems hard to believe that with a forced induction application there is just a number to use. I would be so afraid of that thing detting from carelessness. Build yourself some knock ears bandit! Get your timing perfect and never worry about detonation again.
     
  9. Bandit723

    Bandit723 Veteran Member

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    Oct 1, 2016
    Waupaca WI
    I think the direction I am going to go here is to purchase a MSD Programmable Digital 6AL-2 Ignition Box. The Mallory dist is a bit of a pain to keep taking out and adjusting the advance limits so making changes just to see what happens takes time especially when the car is at the dyno shop and paying good money just to have them pull this thing is just wasted time in my opinion anyways.

    Also then hope to get the benefit of better timing when running the car at pre boost levels and still get the boost retard needed. This should also help the dyno shop in getting the engine dialed in better and quicker.
     
  10. biker

    biker Veteran Member

    Sorry man, I missed this post. I said 30-32 only as a safe staring point for a small block Chev. It may want more total timing, I doubt that it would want less. As for what the motor "likes^, that is easy to tell with a vacuuum guage and tach at idle when you are setting INITIAL timing, but to set total timing, you have to be holding rpm at a point where the timing stops advancing itself with the weights (3000 on my car) and use the dial-back feature of the light (set at 32 advanced or whatever your starting point is) and check he TDC mark on the balancer/tab with your light. Once that is set, that is your TOTAL timing, and you can now CHECK your initial timing for curiosity sake to see where it is, but you cannot change the initial setting without now changing your total timing. Total timing is more imprtant. Now go for a WOT run, a part throttle, hot, high load run, and see if it rattles, if not, repeat above with 33 degrees advanced and see if it is tronger and still does not rattle.
     

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