When you have a carb heater you go from the Intake to a t and one leg of the T goes to the carb heater. The other leg goes to the valve for heat control then into the heater. The carb spacer water outlet on some trucks cam back to the water pump and was tee'd to the return from the heater core at the front of the engine. Others were Tee'd to the return hose up by the firewall.
Old Fords RuleWas a Ford Service Tech
71 F250 with Shell Car 390 NP435 Dana 60 3.73s, PS, PB, 750 EC VS Holley Accel Points Eliminator.
98 Volvo S70 2.4T Auto71 Service manuals Volumes 1,2,3 and 4 So ask away. My GallerySpark test