LS conversion VA heater plumbing

[71RS/SS396]

Imo the only thing that your video shows is that your heater core is adding efficiency to your cooling system which is dropping the temps slightly. If your car does not stay at the temp of your thermostat your cooling system is lacking the proper efficiency in some fashion whether it be from airflow, water flow, or the size or efficiency of the radiator. The thermostat is nothing more than a bi-metal spring, it only knows temperature and opens and closes based on that.

[Chad-1stGen]

Originally Posted by 71RS/SS396

Imo the only thing that your video shows is that your heater core is adding efficiency to your cooling system which is dropping the temps slightly. If your car does not stay at the temp of your thermostat your cooling system is lacking the proper efficiency in some fashion whether it be from airflow, water flow, or the size or efficiency of the radiator. The thermostat is nothing more than a bi-metal spring, it only knows temperature and opens and closes based on that.

You seriously think a vintage air heater core adds that amount of efficiency to an idling motor? A motor that runs under 200* in road course situations I might add. I get that this is a controversial topic. I did a lot of internet searches on it myself and came across tons of threads that seemed split down the middle between folks swearing it makes no difference and folks who saw a difference. I'm one of the ones that saw a difference.

The fact of the matter is that the LS thermostat is on the inlet/supply side and when the thermostat is closed and the heater ports are blocked there isn't any coolant flow across the side of the thermostat that senses temperature.

ETA: When I made that video it was after a radiator swap in which I changed the location of the steam vent from the heater hose return to the radiator. This is the whole reason I explored the issue because after the swap I saw a more pronounced difference in behavior at idle. I've since switched back to having the steam vent plumbed into the heater hose return and the difference in having the heater hose valve open or closed is less pronounced now because even when the heater core is closed there is still some coolant flow across the thermostat sensor from the 1/4" steam line.