Having the ability to work with a set of aluminum heads as opposed to iron heads is a nice upgrade on paper, but it presented CFE with a whole new set of challenges. Since the INDY cylinder head comes with a larger valve size and port volumes, CFE needed to come up with a way to shed some of that volume to stay within the Super Stock rules.
“The head as sold from INDY comes with a 235cc intake port, a 105cc exhaust, and a 69cc chamber. So a tremendous amount of welding was necessary to get the material needed to have full clean up with the intended port design. Working with a third head casting as a model and lots of epoxy, once a satisfactory intake port, exhaust port, and chamber were hand finished, the necessary data was taken to compose a CNC program to port what would become the actual race heads,” Kieffer explains.
Kieffer explains further what development went into these custom heads.
“We began by shortening the intake port via machining the intake flange. From there, we dammed the port openings with a bridge of weld across the floor and raised the floor with epoxy. On the exhaust side, the dogleg AMC ports were also a problem as nothing there really spells horsepower. So we filled the exhaust ports with weld and redesigned the exhaust ports and engineered a new bolt pattern. Both the intake and exhaust seats were finished with a CFE Pro Stock-style valve job and all the volumes were finished within one cc of the NHRA-specified factory volumes,” Kieffer says.
