[cobraman428]

First of all, if the car does not overheat at road speeds but does at idle it is simply an "air flow" issue and not anything with the coolant/water pump speed or pully speed. With the radiator cap off, there will be some bubbling due to pump pressure and everything expanding as it heats up. The tank should only be about 1/2 to 3/4 full when the engine is cool. You MUST run a thermostat. Repeat, you must run a thermostat. On my 428 I knocked out the center spring and it leaves approx a 5/8" hole. Takes alittle longer to warm up but big deal. You definetly need to run a thermostat to create a restriction or backpressure on the waterpump. I went through all this on my freshly 400 hp FE 428 and worrying about overheating and determined my electrical temp guage was giving me crap readings so I went with a mechanical guage that cannot lie. I also went with customized fan and shroud. e-mail me if you want pictures. Wanta check your air flow or lack of it at idle, turn on your engine fan with car at idle. If it begins to overheat, go inside your house and get your floor fan or oscillation fan that you have to blow on you while watching tv and place it in front of your car. borrow your neighbors if you have to but keep adding fans and you'll soon realize your electric engine fan is undersized. You need near 4000 cfm on a 427 or 428 on a 90 degree day at idle. Also, the electric fan is best when the blades are about a 1/2 inch from the radiator fins. You want to avoid air cavitation but want too achieve 100% draw. My 428 can idle forever on a 95 degree day now and stay at 180 degrees. Also dont be alarmed if it consistently runs at 200 degrees especially, If you have an all steel engine block and heads, 200-205 degrees is no big deal. At those temps your getting better fuel combustion. Sorry, ...enough rambling.