Gt-40 Cooling (or Lack Thereof).

[cobrashoch]

BlackJack - I'm going to give you a trade secret now and this reply is long so bear with me. I was gong to tell you this at the spring fling when you, I and Hersh was together but we got to rapping and I forgot.
I think your problem is trapped air in the heads of your engine to. None of the fixes described will KEEP the air out even if you can get the air out. So go to your friendly Chevy dealer and look at the reverse cooling setup that is on new Corvettes. You will notice 4 tubes that directly go to the top or the engine from the water pump. This is for visual referance only. Now if you go to the top of your engine(windsor?)look for the high spot of you engines coolant passages. Most cases it in the intake manifold though. Now it gets tricky. You will need to drill holes in the manifold at these high spots and weld in a fitting(s) or install fittings directly on the heads that will let you run a hose from there. Install a petcock valve on this(each) line and run this line(s)to a purge box somewhere high in your car. Then run a hose to the radiator hot side from the purge tank. You have some options now. This purge tank should have a line coming off the top of it to your expansion tank. Or you can also run the coolant out of the thermostat housing to this purge box to then on to the hot side of the radiator via a hose.
IN PRACTICE - The idea here is to crack the petcock valves just enough to let the coolant/air mix go to the purge tank. This will keep the air out. I once seen a mustang that had 4 half inch lines that were on each corner or the intake manifold. They went to the purge tank and the thermostat housing was blocked off! The car ran great and cool to. Now you may think if you run these bleed lines they can go directly to the overflow tank. In truth they can and you will be doing the same thing. But now for another tip. I am going to use a heat exchanger in a that surge tank to cool/heat my oil too, so if you just go to the overflow tank you can't use it to cool your oil to.
This tip was used in my Pantera racing days back in the late 70's I'm sorry to say. I got it from Peter Revson.(sp) In practice it made up for many of the small problems that were listed in above threads esp. in boil over situations. Should be standard equipment on all coolant cooled mid ship mounted cars in my mind.