With the radiator lower than the engine you end up with trapped air in the system. In the Factory they used a vacuum-pressure fill system to get out the air, then fill. On some cars with the heater core mounted higher trapped air would minimize the amount of heat output. You can loosen a high heater hose slide it back. drill a small bleed hole, Run the car engine and when you get coolant out the hole slide the hose back and tighten the clamp. I have seen some guys use a drain petcock on the intake manifold to bleed out air. With an over flow can, the air in the system will expand and expell coolant, then when the system cools down draw the coolant back in the system. I have seen some engine installations where a radiator cap contraption has in in and out radiator hoses and is mounted highest in the system. Summit Racing Part Number: BCI-72099. I couldn't find a good pict, with one of these you don't use the radiator mounted cap after you get most of the coolant in the system . top it off with the hos-cap. 60's tunderbirds and some Cobra Kits used the combo small tank'-filler- radiator cap.
Last edited by timothale; 06-24-2013 at 08:32 AM.