Joystick, that is unbelieveable! Not doubting your claims/research, but that is probably the most counter-intuitive thing I have ever seen regarding an ignition curve! Retarding the timing at start or high idle is a common practice in many engine applications, but I dont think I have ever seen this in our applications. Its WEIRD. It could be that as per truckrcers findings, that the sensor was bombed, giving you those results?
The reason I raise my question is that I have an OSGF40 that is behaving weirdly. I dont have the original ignition module, and am trying to match a standard ignition to the engine, but cannot find an area of comfort to get this engine to run properly. I suspect that there are some carb issues that may be contributing to my frustration, but I have also heard that the ignition module was purpose built for this engine, and may have odd curves. In some forums, people have said that there is NO spark during low rpm, and requires a speedy starter in order to get the ignition to fire. Some say that OS didnt want people handstarting them in order to avoid injury, so they cut spark at hand starting speeds, yet I have seen videos of people handstarting them
The sensor is not placed where it could be set easiy at 28Deg BTDC so perhaps there is some truth in it. When using an NGH 38 ignition module, with sensor as close to 28Deg BTDC it runs, but battles a bit. I tried it at the stock sensor setting, and I got BIT...bad.It was firing after TDC and would rotate and smack the back of my fingers before I could get them out the way! At 28Deg BTDC my Align starter, with the throttle opened slightly, would NOT rotate the prop past the compression stroke!
Truckracer, would it be possible to share your published findings, or provide a link....if its public info?
To the OP, my apologies once again, I am going to find a suitable place to move the topic so that I dont derail any further...