During the formative years of the high performance industry, the "trick of the week" seemed to come and go on a regular basis. Lots of those tricks revolved around header bolts, and attempting to keep them tight under heat, vibration, and constant pedal mashing bursts of speed. Enter the SplitLock, which gives a whole new twist to the theory of mechanically locking fasteners. Designed and manufactured by Breslin Performance Products, these innovative bolts (available in 8740 chrome-moly steel or black oxide finish) are comprised of a 3/8, 12-point head, combined with a 9/16 head flange, for additional clearance around your primary tubes. What makes this even more interesting, the center of the bolt is "rifle drilled," or precision machined and threaded, and the lower portion of the threads feature cross cuts. Then, there's a set pin (made of 18-8 stainless steel) that threads into the center of the bolt, which, when locked in position, forces those cross cuts to expand the shank within the bolt hole, ultimately locking the fastener in place. Gone are the days when header bolts would loosen and immediately cause the gasket to blow out. Now you can put a positive lock on your header bolts. SplitLock fasteners are available for all popular applications. The folks at Breslin recommend running a tap into your bolt holes, to ensure a good clean thread surface. It sure helped on our mock-up block, as paint was interfering with the threads.The folks at Breslin recommend running a tap into your bolt holes, to ensure a good clean Get your header positioned by loosely threading in the outermost bolts. Then, slide the gasket in place.Get your header positioned by loosely threading in the outermost bolts. Then, slide the ga Thread the bolts in and hand-tighten, making sure each lock pin is loose. Next, torque the bolts to 35 ft-lb, beginning in the center and working outward.Thread the bolts in and hand-tighten, making sure each lock pin is loose. Next, torque the Finally, the set pins are torqued to 96 in-lb, in the same sequence, using a 1/8-inch hex bit. Now your header bolts are securely locked, giving the gaskets a nice, even crush pattern for optimum sealing.Finally, the set pins are torqued to 96 in-lb, in the same sequence, using a 1/8-inch hex This close-up shows the cross cuts at the base of the bolt shank. Only the top of the set pin is threaded, allowing the smooth lower portion to force the bolt's cross cuts to expand against the bolt hole.This close-up shows the cross cuts at the base of the bolt shank. Only the top of the set The artwork shown here demonstrates the installation sequence, and how the set pin forces the cross cuts to expand the bolt against the threaded hole.The artwork shown here demonstrates the installation sequence, and how the set pin forces SOURCES Breslin Performance Products, LLC P.O. Box 6147 Glendale, AZ 85312 Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!
