Mark

I read your other thread. so I see what the context is now. Here is my take.

With gasket issues, the cylinder pressurizes the cooling system. Thermostat type, or lack of, should not have any impact on that. In reality, if you removed them, your truck would never warm up in colder weather, and would take an hour in warm weather. That is bad for the motor also.

That influence of migrating cylinder pressure stands to push out coolant, and the only way to stem that, is to reduce cylinder pressure. So if you have some highly advanced timing, it may help to retard it, but that is a band aid at best.

Solution:

You could go to a coolant with a high BP, like evans, and then drill out the cap, venting it to the atmosphere, that will give the excess gas a place to go, without pushing coolant out. In lieu of evans, you could use 90% EG, that would have little vapor pressure at normal loads and temps. You could probably use it as a daily driver for quite a while this way.

Basically, you are working WITH the problem, allowing it to purge.