COMBUSTION CHAMBER MOLDS
When making chamber molds for a variety of purposes, including holding up the valves on the assembly bench (As opposed to a beanbag or shop rag) common auto body filler (Bondo) works very well. It’s fast and very inexpensive. Just mix the body filler and fill chambers of an assembled head. The molds release easily if you just spray a little silicone into the chamber for a release agent before filling. At pennies per mold, it’s a very practical way to make enough molds of each chamber for assembling heads or for many other purposes such as determining piston dome requirements, valve relief locations, etc.

Keith Morganstein
Max Effort Engines
Sutton, MA
April, 2014