any ideas? working on my dads 35 ford .car seems to cool fine sitting in driveway.take it down the road and within a half mile the temp gauge jumps from 160 to 210 and blows the antifreeze out of the radiator.removed radiator(that was fun) and had it flow tested. flows 35 gpm (good) any input on this would be appreciated. flatheads were before my time and dont know a whole lot about them.motor was rebuilt when he bought and has low milage on it since rebuild,possibly has been this way when he got it.car is stock.were water pumps a problem on these engines.It almost acts as if the waterpumps arnt pumping enough fluid?