Reply to "Overflow tank"

Hi Doug,
Good discussion topic, as this seems to be a relevant topic for many with mid engine config.

My experience makes me first ask the question.. Do you have an air bleed line coming from your radiator back to the swirl tank? When I built my GT40 (basically the same car as we know), I had a major issue with the temp at first. Big swings in temp and simply not stable. First, I ran two lines from the top corners of the radiator into a "T" then to the swirl tank. Significantly improved. Then I tapped into the intake manifold (note: weber induction) on both bank water jackets and ran lines into a "T" and then forward and "T'd" into the line going into the swirl tank. Then, I ran the engine at idle with the swirl tank cap off. Set the coolant level so that running at idle with cooling fans running the tank was full. My logic was that this was a stable "norm", and the expansion tank would be used whenever I got into "hot" running conditions. I can honestly say...I did not have to revisit it even once.

coolant bleeds pic

Hope this helps.....