[302crew]

ive just finished building my new mustang this is the combo 86 bottom end 87 heads and an 86 intake here is the problem it overheats it has a new water pump radiator and cap and thermostat. could the problem be that the gaskets arnt right with the 86 and 87 combo im using 87-93 gaskets any suggestions would be very much appriciated. also whenever it overheats it gets up to like 270 i stop and let it cool off and there is missing out of the radiator and the overflow is pretty full and i did a presure test on it and it was fine please help me