240 is pretty hot! There's lots of tricks to try to get the car to stay cooler! Some cheap....some more expensive! Try the simple....CHEAP stuff first, then throw money at it!
First of all, I'd recommend you put a 190-195 t-stat in it. Test it first in a pot on the stove and a thermometer to make sure it functions correctly! (they do come defective sometimes!) If that doesn't make much difference, pull the water pump and divider plate off the timing cover and measure the gap between the impellar and the divider plate....the closer they are the more efficient the impellar will be. (you can adjust with a hammer)
Next as mentioned there is a lower air baffle between the valence and the core support that helps channel the air comming into the front of the car. Bjorn will probably pipe in about the masticated fillers that seal the sides of the core support, but mine are not in place and the car cools fine. I do have the upper X panels and lower air baffle in, though.
Another thing to check could be your fan clutch. I've switched to dual electric fans so someone else will be more help at checking the fan clutch.
