The Edelbrock heads, which Hafliger treated to a massive porting job, are part of the 600-plus-horsepower formula. Out of the box, these heads have 64cc combustion chambers. With porting, Hafliger opened them up to 72cc. He also reground the valve seats to fit 2.08- and 1.60-inch valves (stock sizes are 2.02-/1.60-inch). Because he opened the chambers so much to improve flow around the valves, Hafliger chose flat-top pistons and milled the deck so they fit 0.005 inch out of the hole. He needed that combination to get the desired 10.9:1 compression.