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Old 01-27-2020, 06:10 PM   #30
J and M Machine
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Join Date: Oct 2010
Location: 40 Mt.Vickery Rd. Southborough,MA 508-460-0733
Posts: 352
Default Re: Exhaust port crack.... need help!

Quote:
Originally Posted by Russ/40 View Post
I'm a big fan of brazing, and have a particular love for silver soldering. The material flows better than brass. I find it a simple and effective solution for many repair situations. One thing I've learned recently is to pay attention to the thickness of the material. Thinner areas of cast iron cool at a much faster rate than thicker areas, and will crack when cooling. Particularly in engine blocks where there is a huge heat sync, the repair will crack if thin.
After applying the solder, immediately peen it, then with a low flame control the cooling down rate, and you will greatly reduce the chance of a cooling crack. You just have to get the feel for the temperature control.

I would be weary of brazing a Model A as the iron is an uneven thickness and you will end up doing more damage than the initial crack you're trying to repair. The pictures I have posted represent a brazing job on cylinder head from the Navy base in Richmond, a submarine welder I was told. i peeled it off like old gum.
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