On my '23ish T doodlebug, I noticed the other evening while it was dark out, the exhaust pipe is glowing red at what seemed like a happy advance setting on the engine (not noticeable during the day). I played with the mixture, but always ended up in the same spot---which is about 1 1/8 - 1 1/4 turned out of the needle on the NH carb. So for the heck of it, I pulled the advance as full as it would go. That cured the red hot exhaust pipe.
This however seems to go against all of what I am "supposed" to be doing---in that at low speed heavy load, I should reduce the timing (the type of driving I was doing),
I have had no overheating issues or coolant puking out the overflow with my previous setting which was about 2/3 travel of the advance lever. However something I have noticed it started doing recently was after shutting off, after about 10 seconds, it would backfire out the exhaust--no doubt because of the super heated pipe/combustion chamber.
I also double checked my timing / timer setting today, and all is good. I have an Anderson style timer and it is set to just start buzzing #1 when the adavance lever is pulled down about 2-3 notches, when the engine is about 10-15 degrees ATDC. With the lever fully retarded, there is no buzz of the #1 coil.
Do I have one of those freak vehicles that just wants full advance at all times?
When you say low speed heavy load, do you mean low engine speed? My guess is that, even though the vehicle speed is low, the engine is turning fast enough to want more advance than you had been using in the past.
Mark, that is my feeling too about the engine turning faster thus needing more advance. I was actually snow plowing the other night when I noticed it. But it was Ford Low, Auxiliary trans low and the 7 to 1 TT rear axle. So speed wise, I was not moving fast and as far as engine speed, the carb was opened up maybe 1/3 throttle--which seems to me a little low for full advance.
You should drive the car as advanced as you can for the driving conditions. Find the spot where you have the smoothest engine and the most power. The point will vary depending on whether you are running on magneto or battery or whether you have a distributor. But pull it down till it has the most power. If it begins to run rough or ping, or knock, push it up just a little. If you run on magneto and coils, that point might be a few notches. You will notice with mag, the spark advances or retards in nodes. That is as you advance the lever a notch or two no change is noted, then advance another notch and the engine will speed up. This is repeated by a few notches with no change and then another notch and the engine speeds up. About half way in each node will give you the smoothest run because all coils will be advanced the same amount. If you are on battery or a distributor, the advance will be continuous as you pull the lever.
If you have slack in the mechanism, you will also notice that the timer will not move for a notch or more when you change the direction of movement of the lever. So you might need to do a little bit of experimentation until you find the "sweet spot" for any particular driving condition.
If the manifold gets red hot, you are too retarded. This could also cause the exhaust valves to get too hot and could warp or burn the valves, so advance a bit more.