When you torque a cylinder head to a block, the bolts pull the cylinders out-of-round,creating an egg shaped bore, that was previously perfectly round with a fresh bore and hone job. A torque plate is an absolute necessity for any high performance or racing engine because the "plate" simulates the stresses of the bolts being torqued, and a head installed on an engine when the cylinders are bored and honed. So when the cylinder head is actually installed and torqued in place, it makes the cylinders back perfectly round as when they were bored. To see how much of a difference it makes, go to a machine shop some time and watch one being bored w/plates. Many Winston Cup teams have plates that they bolt to every surface of the engine externally to simulate and eliminate this at that extreme of a level. They even circulate heated water thru the water jackets as the block is being bored to simulate the thermal expansion of the block at operating temperature while boring and honing it. Kinda' extreme for us, but they do it because they found it makes a difference and more HP. We found early on with Cotton's 292, that even with a torque plate, we were experiencing an excess oiling in the #6 cylinder! We couldn't figure out why just #6 was always the culprit. We had an extremely tight relationship, with then head engine builder for Donnie and Bobby Allison, Dave Vaselnuick,(if that gives you a time frame of when it was)and he immediately knew what the problem was.....On an inline, more so than a V-style engine, when you install the bellhousing, it in the same way a cylinder head does when torqued, was distorting the #6 cylinder, making it out of round. Dave told Headrick to torque a bellhousing to it when you bore and hone it just like a torque plate for the head. He did,problem solved. Nascar guys were doing all those tricks in the 70's. The bellhousing plate for the inlines is a for real "speed secret" and "trick of the trade" that I could probably charge money for, but its here for free. One final note about Dave, he made the "Alabama Gang"....The "Alabama Gang"! And he is one of the many "links" in the chain that helped put Cotton and Headrick at the top. I had the priveledge of working with Dave for two years in the mid-90's when he was transitioning from California to Charlotte to become knee deep in the Busch and Craftsman Truck series.He headed up a Pro Stock R&D program for Headrick,while he was preparing his own shop in NC. To be in the presence of someone like him day-to-day, was like being amongst royalty. He is still currently dominate in it today....a true unsung hero!
Last edited by CNC-Dude; 12/02/08 02:52 PM.
