Pettis Performance 598ci Race Engine - Big, Wild, & Nasty Part One Photo Gallery
Not only was the lifter bore enlarged, Pettis also moved it over 0.050-inch. This accomplishes a few things, first is that it allows room for a larger pushrod without having to ruin the heads. Secondly, the modification allows for a slightly straighter pushrod angle. Both are critical to running higher rpm levels while still maintaining valvetrain reliability.