Can someone tell me what the purpose of the exhaust crossover passage is. The edelbrock performer rpm does not have one. The regular performer does. What does it do?

 

A gas engine has many different systems, the heat crossover is only a part of a quick heating system. When cold start's occure the exhaust crossover valve should close wich makes hot exhaust, crossover underneath the intake manifold wich heats up the center of the engine as well as the fuel and air. There is usually a hot air flap on the air cleaner that will close off and allow the hot air to enter the air cleaner. Both of these are trying to heat the engine quickly for better drivability. For racing and street use, people usually block these passages and remove the exhaust valve.