Old Vet

Shouldn’t a 1967 350HP & AC with 4 speed have the water bypass hose connecting aluminum intake to the water pump?

My buddy has this setup and engine has new 180 degree thermostat, new temp sending unit and gauge and car operates at mid 150 degrees. This temp has been also verified with thermo gun....his mechanic suggests removing bypass hose and plugging to increase operating temp. I’m worried if it’s original nipple in aluminum intake it could take out threads removing from intake causing more heartburn....

1Hotrodz

Plugging the bypass hose won't increase engine temp. The bypass allows the water pump to circulate coolant thru the engine while the T-stat is closed. Did you check the T-stat for proper operation? If not; You need to remove the T-stat and put it in a pot of water on a stove and heat the water and see when it opens.
The rating on a T-stat is the temp at which it starts to open, so 180°F means it starts to open at 180°F. I suspect a bad T-stat or an air pocket in the cooling passages. But whatever you do, do not plug the bypass hose.

Nowhere Man

I suggest you find a mechanic who has a clue. The above is correct

Powershift

Agree with the others. The AC cars also have a vacuum operated shutoff valve on the 5/8 inlet to the heater. Make sure it is closed (when possible and heater not needed). Having this valve open will allow the heater to transfer some engine heat to the cabin.

Larry