[bobcowan]

Agree with the above: check the thermostat.

The bypass hose plays an important role. The normal flow of water is through the block from front to back, up to the rear of the heads, and then through the heads from rear to front, and then out the open thermostat. During warm up the thermostat is closed. Water then flows through the bypass hose, and back into the water pump. That keeps water flowing through the engine for an even warm up, and prevents hot spots.

A smart builder would only remove the bypass hose if the thermostat was also removed. But you would really only want to do that on a race only engine. Not a good idea for a street engine.