Trying to get that second plug removed from the intake to put a water temperature gauge in... Tried heating it with a small torch before I break out the big acetylene stuff . tried tightning and loosening won't budge.... I might drill it... Any ideas? I have used penetrent oil...... use the big heat? or drill?

Heat intake not plug. Use 6pt socket and breaker bar
For max torque

Just before you put the breaker bar to the plug press a ice cube into the plug. Sounds silly but the difference between the warm (hot) intake & the cold plug will help.

Purchase a 6 point impact wrench socket that fits. Before you break your regular socket set socket.

Hit it with the acetylene torch this morning, took two minutes of heating, came out like it was put in yesterday!!!!! I was afraid of getting cast too hot, kept the heat away from the plug,but it worked well. the bottom two threads were rusted and the upper threads were as shiny as the day it was put in in 1969....