Should you run a car without a thermostat?

The reason you should ALWAYS run a thermostat is to ensure the rear of your engine block gets exposed to cooling water.

With the thermostat and temperature gauge located at the front of the block, removing the t-stat causes the cooling fluid to be pulled back into the radiator (recirculated), which results in water only circulating through the "front" of the engine. The t-stat "cycles" to ensure cool liquid is forced to circulate over the entire engine (front to back).

If you run without a t-stat, it's very possible your temp gauge is giving you false readings, since the only portion of the block that gets cooled water is the front - where both the temp gauge and t-stat is located...which means your back cylinders are probably running considerably hotter than your gauge indicates.

On the detonation, check to make sure you don't have any vacuum leaks; check the vacuum advance to ensure it's working properly; make sure you're not sucking any air through the carb from an open port or internal crack; check to ensure your operating temperature is consistent with the t-stat you're running (remember, you can run too cold a thermostat, which is nearly as bad as running with no t-stat); make sure you don't have "bad" fuel (or fuel with lower octane than your engine requires); and if all of these measures check good, check your static timing to ensure you haven't jumped a tooth on the timing chain; and, finally, check cylinder pressure to ensure it's consistent with your build and fuel octane.

Again, IMHO, just a few things to be aware of, and to try.

Southernman