04-06-2021, 05:42 PM
Hi Oxford Jack
A discrepancy of 1 1/2 inches on the cam pulley corresponds to 81 crank degrees which is absolutely miles off, so something aint right.
I'm just wondering if the strobe is being triggered correctly from the plug lead ? If it has the "clothes peg" style inductive pickup then this senses the spark current and is polarity sensitive. If the polarity is wrong then it could be that it is triggering when the "points" close rather than when they open which would give the sort of offset you are seeing. It might therefore be worth trying it in the other direction (it has an arrow on) and see if that is better.
Fot a standard DK4 i'd expect the auto advance to increase about 10 crank degrees between 1000 and 2500 RPM, which will be about 5mm at the pulley rim so 1/8 inch (3 mm) is believable, but check again once you have a proper trigger.
I use an inductive triggered xenon strobe (with its own 12v battery) and a pointer on the cam pulley and it works fine. It's a little sobering to see how much timing scatter is introduced by all those meshing gears between crank and distributor ! Interestingly I find that scatter is a tiny bit less when the dynamo is set to winter charge, maybe the mechanical load damps things out a bit ?
A discrepancy of 1 1/2 inches on the cam pulley corresponds to 81 crank degrees which is absolutely miles off, so something aint right.
I'm just wondering if the strobe is being triggered correctly from the plug lead ? If it has the "clothes peg" style inductive pickup then this senses the spark current and is polarity sensitive. If the polarity is wrong then it could be that it is triggering when the "points" close rather than when they open which would give the sort of offset you are seeing. It might therefore be worth trying it in the other direction (it has an arrow on) and see if that is better.
Fot a standard DK4 i'd expect the auto advance to increase about 10 crank degrees between 1000 and 2500 RPM, which will be about 5mm at the pulley rim so 1/8 inch (3 mm) is believable, but check again once you have a proper trigger.
I use an inductive triggered xenon strobe (with its own 12v battery) and a pointer on the cam pulley and it works fine. It's a little sobering to see how much timing scatter is introduced by all those meshing gears between crank and distributor ! Interestingly I find that scatter is a tiny bit less when the dynamo is set to winter charge, maybe the mechanical load damps things out a bit ?