Hello Everyone I'm new hear and need help.Just got a new 36 dodge coupe with a 340 small block.I changed the heads to Edelbrock rpm and the intake to the Edelbrock rpm air gap.Put in a new aluminum radiator new water pump new thermostat.Overheats now after startup.Engine goes up to 250 and the hoses in and out of the radiator are cool.Can't figure it out.Also I thought maybe I was having a problem with maybe air in the cooling system so I purchased the air evacuation system from Summit and used it to put in my antifreeze and it worked well but the problem is still there.

 

Wow, Hoses are cool to the touch?
Check it with a Heat Temp Gun and see what it says?
Is the car boiling over?
Could be possible that the Gauge Sender was damaged during the change over?

 

if engine is hot and hoses are cool, maybe there's a blockage in radiator or the tstat is garbage?

 

Pull the T-Stat out and run it and see what happens. I also drill a1/8th hole in the flange in the stat to let the air out. Could also have the wrong head gaskets and a water passage is blocked some Chevys were like that. You can also take the radiator cap off and see is any water is moving.