[jimf]

Priobe; Since holding the throttle plates open and allowing the hot air out did not seem to work, it sounds to me like the heat is soaking into the carbs via the physical connection with the manifold and the manifold to the heads and block. The alterations you have made are partially compensating for the problem but the problem still remains and that is the heat soak. So how can the heat soak be eliminated or stopped. I think that Eljaro is on to the answere with getting the heat out of the engine. If a person had one of the electric water pumps and electric rad fans, one could set it up so that after shut down the water pump kept pumping and the rad fan could be set to reverse and blow out the rad untill a preset temperature or time period was reached and then both of them shut off. Even if having a reversable rad fan is not possible then having a regular one continuing to run after shut down along with a electric water pump should make quite a difference to the amount of heat that gets removed from the engine compartment.