Removing 1/2" Drive Plug From Rear of Eldorado Cyl. Head

[carlhungness]

My '76 Eldo engine has a 1/1/4" threaded steel plug on the rear of the right cylinder head. It has a 1/2" drive square for removal. The plug is frozen in place and I am imagining I need heat to remove it. I tried the 1/2" breaker bar with a 4' tube over it and couldn't budge the plug.
I see a couple of methods to remove on YouTube. First, the plug is heated cherry red and then paraffin is introduced, so that it will run down the threads. That method may assist, but my engine is installed so getting the wax down the threads is iffy.
Next, cherry red then cool with water quickly and try to remove.
Thus, seeking suggestions. As noted, since the engine is now installed I can only put liquid on the top of the plug and hope it wicks its way down.
If left to my own devices I would have heated the area around the plug, not the plug itself, so I don't know as much as I need to know.
The photos should show the breaker bar in the plug. Those shiny headers are ones I spent hours smoothing, then had them Jet Hot coated.

[The Tassie Devil(le)]

G'day Carl,

As the engine is not in the constraints of an engine compartment, you could try freezing the plug by spraying it with some sort of refrigerant in an attempt to "shrink" the plug.   This "freezing" might just shock the thread into submission.

Or, if the worst comes to the worst, carefully drill it out, as it will only be cast iron, and making sure that you only attack the plug, and then clean out the thread in the head after the guts has been removed.

Bruce.

PS.   I have broken those breaker bars in the past using the pipe extension method.   And, when they break, one has to be aware of the sudden snap, as falling really hurts.   Well, the landing is the worst.

[carlhungness]

   I have no experience at all with cyrogenics, and have never seen a freezing method used. I can heat treat a tool by eye and have it hold an edge but I don't speak fluent freezing at all, so will leave it for now.
   I'll be careful with the breaker bar.

["Cadillac Kid" Greg Surfas 15364]

Carl,
It seems you have reversed the heads and installed the drivers side head with no heater water outlet on the passenger side.  Is there a fitting on what now is the front of the head you have on the driver's side?
Greg Surfas

[carlhungness]

Hi:
  I didn't reverse the heads, the engine came to me assembled. Yes, there is an outlet on the left front that had a tube fitting, and I was able to get it out with a socket. I'll plug it with the one I removed from the other side.
  Hope the reversal, (whomever did it) doesn't need to be reversed.
   I heated the plug, socked the visible threads with paraffin, waited about ten seconds, doused it with water and tapped my breaker bar in. She came right out with no extra leverage.
   I need the hole open in the right head as it will accept my heater hose and with a dual fitting I'll make I can screw my water temp gauge into it too.
   

["Cadillac Kid" Greg Surfas 15364]

Glad it worked out. A common error.
Greg Surfas

[carlhungness]

  It really works out well if you want to run a heater hose right from the firewall, I may even make a hard line with rubber ends.

["Cadillac Kid" Greg Surfas 15364]

That is where the original Cadillac POC was.
Greg Surfas