On LS1, LS6 & LS2 engines the crankshaft and factory harmonic balancer does not use a keyway to positively locate and lock the balancer. In high horsepower applications the pulley can spin on the crankshaft sometimes so severely that the crankshaft and balancer can be damaged. The ATI crankshaft pin drill fixture kit is designed to pin the crankshaft in two locations inline to allow a conventional style keyed balancer to be used. You can have your stock balancer machined to have a key way or use this with an ATI balancer. We recommend this for high-rpm, supercharged, turbocharged, or other high-horsepower engines.
