But now, here's something interesting. A cool engine needs advanced timing to get a start and once running, the timing needs to be backed off as the engine warms.
I would be careful with the words here. We don't need to advance timing at all to start, we need enough heat of compression and fuel vapor to ingite. When the engine is cold the compression temperature is lower. Increasing CR improves that. We also need to vaporize fuel. When airflow through the carb is low vaporization is poor. So excess fuel yields enough vaporized fuel to ignite. Liquid fuel doesn't burn or compress. Once the engine gets hot and fuel vaporizes better due to engine heat and carb velocity, we can run leaner and reduce compression to prevent over advanced timing.
Injected diesels don't richen the mix when cold(no need as vaporization isn't left solely to evaporation). But they do add heat by an intake air heater or glow plugs when things get to freezing. Older non computer diesels, like Dodge Cummins 12 valve, can get some extra starting oomph by just barely touching the throttle in cold weather. Too much and I guess you'll be picking up pieces.
I start my fourstroke conversions wet. Finger over the carb for prime and half turn out on the needle. No extra compression needed, and I was starting by hand. Once it warmed a bit I can lean it out.
I wonder what is causing the extra noise? Do you have any more power than ether fuel?
Greg