Preheat cyl before welding??

Hello, I an preparing to weld a nut onto the valve cage nut on my Novo in order to remove it. Should I preheat the cyl. beforehand to reduce the chance of distortion? If so, what temp could I use without causing change of the shape of the bore? I know that 550 deg is the right temp for welding cast iron,is this too much for an excellent bore that I want to use as is? Also, if I use a ni- rod and a d.c.welder, what should the polarity of the electrode be? Thanks very much. Wayne Z.

Hello Wayne. You got a real question there, I don't know what to tell you, but I just wanted to tell you that yes we are seeing it and probably do not know what to do. I am "figguring" you got the whole bunch stumped. Al

O.K.guys, I did th' deed. I put the Novo cyl. inverted on a propane burner and heated until the oil I put in the combustion chamber was 200deg.I then welded the nut two flats at a time,waiting and peening before welding the next two ect. While everything was still hot, I used a torch & heated a spot on the outer edge of the cage nut hole cherry red. After that, a few raps on a big wrench with a big hammer & the cage was out. The grease that I had smeared all over the bore never melted or ran at all! I think that preheating to only 200deg lessened the amount of stress and warping that welding and torching could cause. Thanks, Wayne Z.

Good deal Wayne. Sometimes it just takes some guts and it appears some skill. Nice job. Al