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Mar 19, 2017 7:15 pm
Mar 19, 2017 7:15 pm
Subject: Re: Igniton set up for my M45 engne
Hi Andrew,
My LG6 ignition is by a Vertex magneto and Lucas coil/distributor. In my case, the distributor is a DM6A for which Lucas state a range of 18-20 degrees. It does have a vacuum capsule, which is not connected/operational. The Vertex magneto, which I am told is correct and probably original, has timings advance marked as 0 degrees at 500rpm, 7 degrees at 700rpm, and 14 degrees at 1730rpm. My understanding is that the "rpm" referred to on the data plate is magneto rpm, not crankshaft rpm. Hence these would translate as 1000, 1400, and 3460 crankshaft rpm.
Unless you fitted the DK6A, it might be worth removing its baseplate to see if the advance/retard bob weights and springs are still fitted. If they are, your easiest option might be to remove those and find a way of locking the mechanism so that ignition timing does not vary. Then, at least you have two ignition systems firing at the same point (ideally I understand, with a 2 degree variance between the two systems). The downside is that you will loose the automatic advance, but then as original, you would be driving without that anyway.
Your present set-up must involve a very large variance in ignition firing, depending on engine speed, if the automaticadvance / retard is functioning. You would certainly need to check that, if connected together, that full advance on the column control, plus full centrifugal advance, does not exceed your desired maximum advance. I believe current thinking is 28-30 degrees BTDC.
A separate automatic advance/retard fitting for the magneto would be preferable; but I doubt such items are available?
If it is practicable to separate the linkage between the magneto and the distributor (it is separable on the LG6, Meadows Sanction 4 engine), my "easiest option" recommendation would be to do that. Have the distributor fixed, and set it so that it fires either at 28-30 degrees at say 3500rpm, OR if you don't regularly stretch your engine that far, at whatever maximum advance you wish for your favoured touring rpm. I would then set the column control advance to achieve up to that setting. With that set up, I would run mainly on the distributor, and just switch in the magneto for stretches where your engine speed is fairly constant.
Ideally you need to replicate the original ignition set-up, and play with the advance/retard lever as necessary, or convert to an ignition arrangement where both automatic advance / retard settings match. Of course, there is no problem running on one ignition system only (which, as my magneto hardly works, is exactly what I'm doing), however you will get more complete burning of the mixture with a twin ignition system. When both systems were working on my car, the idle speed increased 50rpm when the second system was switched in.
Laurence
Hi Andrew,
My LG6 ignition is by a Vertex magneto and Lucas coil/distributor. In my case, the distributor is a DM6A for which Lucas state a range of 18-20 degrees. It does have a vacuum capsule, which is not connected/operational. The Vertex magneto, which I am told is correct and probably original, has timings advance marked as 0 degrees at 500rpm, 7 degrees at 700rpm, and 14 degrees at 1730rpm. My understanding is that the "rpm" referred to on the data plate is magneto rpm, not crankshaft rpm. Hence these would translate as 1000, 1400, and 3460 crankshaft rpm.
Unless you fitted the DK6A, it might be worth removing its baseplate to see if the advance/retard bob weights and springs are still fitted. If they are, your easiest option might be to remove those and find a way of locking the mechanism so that ignition timing does not vary. Then, at least you have two ignition systems firing at the same point (ideally I understand, with a 2 degree variance between the two systems). The downside is that you will loose the automatic advance, but then as original, you would be driving without that anyway.
Your present set-up must involve a very large variance in ignition firing, depending on engine speed, if the automaticadvance / retard is functioning. You would certainly need to check that, if connected together, that full advance on the column control, plus full centrifugal advance, does not exceed your desired maximum advance. I believe current thinking is 28-30 degrees BTDC.
A separate automatic advance/retard fitting for the magneto would be preferable; but I doubt such items are available?
If it is practicable to separate the linkage between the magneto and the distributor (it is separable on the LG6, Meadows Sanction 4 engine), my "easiest option" recommendation would be to do that. Have the distributor fixed, and set it so that it fires either at 28-30 degrees at say 3500rpm, OR if you don't regularly stretch your engine that far, at whatever maximum advance you wish for your favoured touring rpm. I would then set the column control advance to achieve up to that setting. With that set up, I would run mainly on the distributor, and just switch in the magneto for stretches where your engine speed is fairly constant.
Ideally you need to replicate the original ignition set-up, and play with the advance/retard lever as necessary, or convert to an ignition arrangement where both automatic advance / retard settings match. Of course, there is no problem running on one ignition system only (which, as my magneto hardly works, is exactly what I'm doing), however you will get more complete burning of the mixture with a twin ignition system. When both systems were working on my car, the idle speed increased 50rpm when the second system was switched in.
Laurence