The motor that 408duster is relating to has .046 thou. piston to head clearance. It is real close to 9.72 to 1. Motor is lumpy, but it is not shaking the car. Idles well at 800 with the ac on. Kicks along at about 3600 on the highway, sings like a bird. 35 degrees of total timing, around 17 at idle. Don't be scared of the cam, you'll like it. This is at 4000 ft elevation, and still plenty of vacuum to run the power brakes. Trust me his wife would kill him if that brake pedal ever got hard from not enough vacuum.