Edelbrock E-Series Cylinder Head Bolt Kit #85492 is designed for use on Pontiac 326-455 engines with Edelbrock Performer and Performer RPM Cylinder Heads #60569-#60599 and #60509 manufactured after 3/12/02. Note that Edelbrock Cylinder Heads for the Pontiac 389-455 engine require a special head bolt. The head bolt boss heights have been changed in the Pontiac cylinder head to eliminate problems with cracking at the upper head bolt boss end for high-output applications. The new head bolt boss height also simplifies the head bolt kit by requiring only three different lengths instead of six different lengths in the previous head bolt kit. E-Series bolts have a yield tensile strength of 190,000 PSI for strong and reliable loading. Bolt threads are rolled after heat-treating for superior form and strength, while a small hex head provides extra space for socket clearance in tight situations. E-Series Cylinder Head Bolts have a durable black oxide finish with sealer and come with the distinctive Edelbrock E stamped into the head.