He means bleed the cooling system.

 

I believe that is an instruction that could be completely stated as, "bleed the lines..."

Due to the reverse-flow cooling and the fact that the radiator is placed very low in the chassis, the LT1 has a tendency to trap air in the cooling system when it is filled from empty. You should find a small bleed screw on the thermostat housing that is used to help evacuate air while the system is being filled. I believe that Shoebox addresses this process on his website.

The bleeding process is very important because, if it isn't done correctly, the trapped air will allow the formation of pockets of steam that inhibit the circulation of water through the system. It is possible to seriously damage an engine at this point in the process.

It isn't too big a deal unless you neglect to do it.

 

Gotcha! Thanks a bunch guys I want to keep learning more and more about these machines!

 

Another caveat associated with the bleeding of the cooling system is the need to avoid dripping water onto the Optispark while the vent on the thermostat housing is open. The Opti is susceptible to being damaged by water. That's apparently why GM Engineering placed it in a spot immediately adjacent to the water pump and immediately below the system vent.

It's a good idea to put a towel or sponge in the area between the two while the bleeding process is going on.

 

Alright.