COMPUTER-AIDED BLOCK MACHINING by Mike Mavrigian One of the prime benefits of owning a CNC machine is the capability of accurizing an engine block to “blueprint” specifications in terms of correct centerline placements. (photo courtesy Sunnen) A full-blown CNC machining center, such as this Sunnen/RMC V40, expands shop capabilities to include not only block and [...]
BALANCING Our crank was balanced at Gressman Powersports. Scott Gressman handled the job using his Sunnen Pro-Bal balancer. We began by first weighing all components (pistons, pins, locks, rings, bearings, rods). The Diamond pistons required no correction at all, with the entire set weighing in at 542 grams, +/- 0.5 grams). The Lunati rods, though [...]
CAM BEARING INSTALLATION Note: The cam bores feature sharp edges. To aid in camshaft bearing installation, first deburr the edges with a sharp scraper. Once all block grinding, tapping, and deburring was finished, the block was thoroughly washed, rinsed, and blow-dried, with 5W30 engine oil applied to the cylinder walls to prevent surface-rusting. The camshaft [...]
The valve reliefs were cut with precision. The intake pockets are 0.270″ and exhaust pockets are 0.064″. Notice that the pin bore location encroaches into the oil ring groove. Diamond supplied a set of support rails that are installed prior to the oil ring package. These provide footprint support for the oil ring package. Scott [...]
HONING THE CYLINDERS Following a recommendation from our buddies at Sunnen, we visited Gressman at Gressman Powersports in Fremont, Ohio (Gressman has built a number of 632 motors, in addition to countless big-number drag, sprint car and road-race engines). Naturally, the Ohio winter weather forced us to drive in sub-zero temperatures. Even with the block [...]
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