January '20

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40 THE SHOP JANUARY 2020 BUILDING THE Nighthawk II LS hemostat to place the nut to the tip of the stud, gently rotating the nut to start the threads. Finger-snug the nuts and then torque using the 2-inch torque wrench extension. The swing area for the wrench is rather limited, so be prepared to be patient. PUSHRODS With one head temporarily mounted (with head gasket and torqued to value), I mea- sured for pushrod length at No. 1 cylinder. With the intake and exhaust lobes on base circle and valves closed, I carefully mea- sured the length from lifter to rocker to the point of contact, inducing no preload. I verified this by re-measuring four times, obtaining a measurement of 7.555 inches. I then added 0.045 inches for lifter preload (COMP's spec for lifter preload is 0.040- 0.050 inches) for a length of 7.600 inches. Our Harland Sharp shaft-mount roller rockers feature lash adjusters that allow for an easy setup with 1-1/2-turn to zero lash, with enough available adjustment with the engine at temperature to fine-tune in either direction (providing 0.040 inches of adjustment at each full turn). Beyond zero lash, I adjusted to provide 0.045-inch lifter preload. Our pushrods are supplied by Elgin. We used its one- piece 5/16-inch models with 0.110-inch wall thickness. Test sweeps (with valve tips painted with black marker) showed near-perfect center contact on the valve tips. A dab of Royal Purple MaxTuff assembly lube was applied to each ball end of the pushrods prior to installation. Our 7.600-inch pushrods were sourced from the Elgin Pro Stock line. Features include seamless one-piece construction using 4130 chromoly, with a 0.110-inch wall thickness for enhanced column strength and stiffness. The pushrods are centerless ground, featuring 210-degree radius ends, and are through-hardened and black oxide-coated. ROCKER SYSTEM The AFR LS3 Mongoose heads require a rocker system that provides rocker pair width location adjustment, since the tapped rocker mount bolt holes are spaced at 2.155 inches on center. AFR does supply aluminum rocker pedestal stands that allow the use of OE rockers, but we opted to go with a newly developed system from Harland Sharp that is specifically designed for the AFR LS3 heads. Features include a one-piece, CNC- machined steel base that bolts to each head (mounting holes align to AFR's unique bolt hole spacing). Shaft mounted 1.72:1 aluminum full- roller rockers register in the stand's CNC- machined position pockets, with each pair of rockers pivoting on 0.624-inch-diameter steel shafts, with each shaft secured to the stand with three 8mm 12-point bolts. This is an extremely sturdy setup with impressive rigidity and outstanding rocker arm operational accuracy. The rockers fea- PRECISION ENGINE The Harland Sharp roller rockers feature lash adjustment. We adjusted to obtain approximately 0.045" preload to our hydraulic lifters. Shown here is the left bank rocker system installed. During test-fitting, we obtained a centered, narrow sweep mark on each valve stem tip. Prior to dyno, we pre-oiled the engine, using our Goodson EPL-120 pre-lube tank. With fresh break-in oil added and the canister charged with compressed air, and with all spark plugs removed, the outlet hose was connected to the oil pressure sender port. Once the tank's valve was opened, pressurized oil entered and began to quickly circulate inside the engine. Oil began squirting out of all rockers within no more than 20 seconds. While the system was under pressure, I slowly rotated the crank in order for each main saddle's feed hole to align with the bearing holes. The pre-oiling job on this build went very quickly and very smoothly, with no surprises.

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