THE SHOP

January '20

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JANUARY 2020 THE SHOP 39 Note: Prior to placing the heads onto the block decks, the M8 x 70mm-long studs must be installed to the underside of the heads (four per head). These protrude through the 11/32-inch holes in the deck ears above the lifter areas. A flat washer and 5/16-inch x 24 nut are installed to each of these studs, accessed from the lifter valley side. This requires the use of a 2-inch torque wrench extension, wrench size 3/8-inch 12-point. Each stud was installed finger-tight. The fine threads and washers must be lubed with a high-pressure lube (CMD or ARP). HEAD STUD NUT TORQUE Following the AFR and ARP tightening sequence, the tightening order was as follows—7/16-inch head stud nuts were fully torqued in three steps, followed by torqueing the four M8 / 5/16-inch stud nuts (accessed from the lifter valley), followed by torqueing the outer 3/8-inch stud nuts, followed by torqueing the five upper pinch bolt stud nuts. In order to access and torque the 5/16-inch nuts to the four studs that were installed to the underside of the head and project into the lifter valley, use of a 3/8-inch 12-point 2-inch torque wrench exten- sion was necessary. In order to achieve 28 foot-pounds of torque on these four nuts, my 13-inch-length torque wrench was set at 24.2 foot-pounds to compensate for the 2-inch wrench extension. Tip: When installing the 5/16-inch nuts and washers to the four studs that protrude into the lifter areas, rotate the engine on your stand to orient the engine so that the lifters are roughly parallel to the floor. This working angle provides better access and prevents the lifters from sliding out. Using a hemostat, install the hardened washers, then use the PRECISION ENGINE Head stud nut torque, per ARP: 7/16"......................................................................90 ft-lb (in three steps: 30, 60, 90) 3/8"........................................................................55 ft-lb M8/5/16".............................................................. 28 ft-lb (Note: In Part I, I inadvertently listed the 7/16" head fastener torque at 65 ft-lb) The Air Flow Research LS3 Mongoose heads feature LS3-style rectan- gular intake ports and boast a whopping 260cc intake runner volume. Combustion chamber volumes were verified using our Goodson burette at 69cc. The "extra" head studs (four per head) must be installed to the head decks prior to head installation. The ARP studs feature 8mm x 1.25 threads in the head, with the exposed 5/16 x 24 threaded ends ex- posed in the lifter area. I applied Loctite 271 to the studs where they engage the heads. Shown here is a rocker stand secured to the right bank head, using flattop 8mm screws torqued to 24 foot-pounds. 800.264.9472 • DesignEngineering.com CATCH DRIPS & SPILLS OIL RUG CATCH DRIPS & SPILLS OIL RUG OIL ABSORBENT CONTAINMENT MAT • SEALED EDGES & BACKING PREVENTS LEAKAGE & SOAK THROUGH • HOLDS 16OZ PER SQ. FT . • 3 SIZES AVAILABLE OIL ABSORBENT CONTAINMENT MAT • SEALED EDGES & BACKING PREVENTS LEAKAGE & SOAK THROUGH • HOLDS 16OZ PER SQ. FT . • 3 SIZES AVAILABLE DEALER & DISTRIBUTOR INQUIRIES WELCOME

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