MD55Bird (7/21/2010)
....As long as I’m doing 30mph or more the temps are fine but when I stop the temps climb up to 205 rather quick.When I built the engine I did not drill the small holes in the deck as many do. My question is: Would it do any good to add a cross over in the rear section of the heads by connecting the 2 pipe plug ports that are on the heads right behind the intake manifold? From your description, this sounds like an air flow issue through the radiator at low speed. A coolant crossover at the back of the block likely will not help in this instance. A short cut fix (if this is an early ‘Bird’) is do away with the one inch spacer behind the water pump and then space your pulley back out the missing one inch. This has been proven to work in some instances for the parade cruiser crowd. And already mentioned is the installation of a restrictor in the bypass hose which is another quick fix for those engines that are just over the edge and need some help in bringing the termpertures back in line.
Here are some other threads on the ‘steam holes’. Those holes are obviously too small to be called ‘coolant holes’. The original intent of those holes is to simply remove the air pockets that can get caught under the decks in the block which turn into hot spots under the right conditions.
http://forums.y-blocksforever.com/Topic31939.aspx
http://forums.y-blocksforever.com/Topic10608.aspx
http://forums.y-blocksforever.com/Topic35997.aspx
And here’s a picture of said hole in a CITE head with the resultant crack going through it.

Lorena, Texas (South of Waco)