Plumbing blueprints.

[MIUPRoadster]

My engine is at the shop. I didn’t tear it down nor remove it. She was bought in the removed condition. Looking for information as to how the back portion of water bath is routed after coming out of second carburetor. I’ve found decent pictures to make it from water pump to the “T” splitting the line and going into first carb. Completely lost as to how it goes back in system, before heater core, afterwards, a “T” or wye back into return from heater core or other.
Haven’t found good picture to replicate.

[redroadster]

Usually the heater core shut off is used to shut down the flow thru the intake ,but when it's cold and it might ice up the carb ,you want the heater on
and it flows ...under the right conditions
A throttle plate can freeze open at /near 40 °