July '20

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64 THE SHOP JULY 2020 With cam bearings installed and checked for cam fit, our COMP Cams billet roller cam was carefully inserted, with journals and lobes coated with Royal Purple Max Tuff assembly lube. Back to Basics PRECISION ENGINE was installed and carefully rotated to verify that no counterweight-to-block clearance issues were present. Our tightest clearance was a healthy 0.100 inch (a minimum clearance between the counterweights and block pan rail area and cylinder bottom areas would be approximately 0.060 inch). During test fitting, the crank was checked for end play. With all main caps loosened, the crank was knocked back and forth using a dead-blow hammer. This aids in squaring-up the rear main cap where the thrust bearing is located. The caps were then fully torqued to 65 pound-feet on all 7/16-inch nuts and 35 pound-feet on the outer bolt location on the number 1 and 5 caps. A dial indicator with a magnetic base was attached to the block face. Using a flat-blade screwdriver, the crank was pushed forward to a gentle stop. The dial indicator gauge was then set at zero. The crank was then pushed rearward to a stop. This was repeated several times to verify the reading. In this case, our crank end play was mea- sured at 0.006 inch. Generally speaking, acceptable end play should be in the range of 0.004 to 0.008 inch. ROD BIG END CLEARANCE A piston-and-rod combo was temporarily assembled, along with a lightly oiled upper and lower rod bearing. The rod/piston was then installed to each cylinder with the rod cap torqued lightly to about 20 pound-feet. While slowly rotating the crank, we checked rod big end clearance at the pan rail and upper web areas. Not surprisingly, we found light contact at the outboard side of each cylinder location, due to the increase in our crank stroke. This is nothing unusual, as clearancing is commonly required when a larger-than- stock stroke is used. All areas were marked. The rod and crank were removed, and the tight spots were easily relieved using a pneumatic die grinder and a milling bit. With the crank and checking rod re- installed, clearance was again checked and verified at 0.080 to 0.100 inch. Next, the block was initially cleaned in a jet wash, followed by a final and time- consuming cleaning using very hot water and Dawn dishwashing liquid. The block was scrubbed using a Goodson nylon bristle brush, and all oil passages, lifter bores and cylinder bores were washed using appropriately sized Goodson bristle rifle brushes, followed by repeated rinsing and blowing with compressed air. Every oil passage was then carefully checked for flow at all main saddle-to- cam-bore locations, all lifter oil passages, etc. Taking the time to thoroughly check these early eliminates any potential nasty surprises down the road. A cursory washing simply is not good enough. The only acceptable result is a block that is 100% clean and free of any and all foreign particles. Once cleaned, rinsed and dry, exposed machine surfaces were lightly coated with WD-40 to prevent surface oxidation. The block exterior surfaces were lightly coated with SEM self-etching primer, again to prevent unwanted surface rusting prior to painting. All machined surfaces were then carefully masked including decks, pan rails, front timing cover and water pump mounting surfaces, etc. We then applied two coats of Seymour IMO industrial enamel paint, in its IHC red color. We prefer this paint to rattle-can engine paints, primarily because many of today's engine paints don't provide what we deem as acceptable coverage. While this industrial paint does require a longer drying period, the results are worth the extra time. CRANKSHAFT BALANCING Crankshaft balancing was performed at Medina Mountain Motors in Creston, Ohio. Owner Jody Holtrey first weighed all components to establish the correct bobweights. This included each rod's big end, small end and total weight, one pair of rod bear- ings, a set of piston rings and piston sup- port rail, wrist pin and spiral pin locks, and each piston. In the old days, when OEM parts were used, it was commonly required to deter- mine the lightest connecting rod to estab- lish a baseline, then grind material from the remaining rods in order to obtain a set of matching weight. The same procedure was commonly required to match piston weights. Thankfully, today's high-quality after- market rods and pistons are so closely weight-matched by the manufacturers that little or no corrections are necessary. Our SCAT H-beam rods weighed in with a With the crank fully installed and main bearings lubed with Royal Purple Max Tuff assembly lube, the main cap stud nuts were torqued in three progressive steps to 65 pound-feet. Thanks to Dart's accurate align boring and SCAT's precision machining of the crank, it rolled like butter and was easy to turn with two fingers on the snout.

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