The above poster makes a good point about the fill point having to be the highest point in the system. He details one good way - another is to take an old radiator cap and braze/weld on a standpipe and mount a funnel on top of that (I use a length of hose and hose clamps). Then the fill point is above everything else. I don't have to do that with Mutt the Race Truck as the Chevy radiator is the highest point but I have done this for other vehicles.

Dan