I just rebuilt a G45 last week. I had this sneaking feeling that my wife would hit the roof if I put one of my engines in the oven, just cuz she puts a roast in there once in a while.

I used an old electric fry pan and set the temp at about 300. After about 20 minutes, the engine was hot enough that the bearings almost literally dropped out. Never had to approach 400F. Hope this helps!

Bob