[Healeys] Temperature thermocouple

[paulbrodeur]

I have a 60 Healey BT7 that sat in the Bullhead City, Arizona desert for 25 
years.

Unable to break free the temperature thermocouple-retaining bolt, I cut the 
capillary tube so as to be able to remove the engine/gearbox.

With the engine on the floor, nothing (penetrators, heat, cold, easy outs) 
broke free the bolt. The last drill bit I used to drill out the bolt was 
7/16" and I am afraid to move to the next size for fear of damaging the 
block threads.

 Any advice on what my next few steps should be would be greatly 
appreciated.

Thanks, Paul