I put a 454 in my wife's '79 Sub a couple of monthes ago.Well now it is getting cold out and it won't produce very much heat inside.It has a 4core rad and had a straight fan.I switched to a clutch fan and it helped a little,but when you get going at speed the air form the ducts goes cool.The core seems to be fine and not clogged.I am not sure if the heater core hoses are routed right.I have 1 going to the rad and 1 going to the water pump.Anyone have a 454 stock in a truck that could tell me where the hoses should go?Any help would be appreciated.Thanks Blazin <IMG SRC="smilies/biggrin.gif" border="0"> <IMG SRC="smilies/usa.gif" border="0">