Less heat after block heater install?
 

I recently installed a tank style block heater, with hose from the engine drain plug to where the coolant goes to the block from the heater next to the oil filter. I'm feeling less heat than before at the vent. Would the coolant prefer this path rather than going to the heater core? Or could it be the Y fitting is too restrictive?

Did you burp the engine?

You have
 

An air bubble in the system - I'm guessing somewhere in the heater core.

The coolant is bypassing the heater through the block heater. You should install a valve in the line with the block heater.

If you look through the parts yards you can find vacuum operated valves. You would be able to T it into one of the ACC vacuum lines to close the valve anytime you turn on the heater.