I don't know how you are checking the timing, but you should be able to set the timing almost dead on before you ever turn the engine over. If this is a new cam, you need to get this figured out before you ruin the cam, look up cam break in procedures on any cam manufacturers website. One of the points will be to have the timing set properly. Also removing the thermostat isn't necessary, (unless of course it is bad) be sure to bleed all the air from the system using the various methods described above. Keeping the thermostat in place should only be beneficial by letting the engine come up to proper operating temperature.
