THE SHOP

January '20

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38 THE SHOP JANUARY 2020 BUILDING THE Nighthawk II LS No. 1 piston was positioned just under TDC. A piston stop stool was secured to the deck with the adjustable stop placed about 0.050 inches below deck. As you'd expect, the crank was rotated clockwise to dead-stop, with a mark placed on the crank pulley. The crank was rotated counterclockwise to stop, with a second mark on the pulley. The point between the two marks indicated TDC. A timing tape was installed with zero at the TDC mark, and the adjustable timing pointer was set to match the zero/TDC mark. COOLANT PLUMBING The heart of our cooling system is Meziere's pro-level 300 Series WP333 electric pump, designed for LSX applications. It flows at 55 gallons per minute, with an overall depth of 7.110 inches. In order to evacuate air from the cooling system, we addressed the LS steam plumbing. Each cylinder head features a steam port at each end of the heads. Since engines are installed at a slight angle in a vehicle, I didn't see the need to plumb all four corners (although it doesn't hurt to allow all four corners to bleed). I capped the rear ports using Trick Flow steam caps, and installed steam fittings at the front of each head using Trick Flow fittings that feature -4 AN male ends. I then tied the left and right side fittings together with -4 black braided hose, with a T-fitting at the left (driver) side. The horizontal right-to-left hose was bend-routed behind the valley plate- mounted K&N breather for cosmetics. The T-fitting was then plumbed to the Meziere water pump's low-pressure port in the pump's left side. A -8 AN male straight thread (O-ringed) to -4 male flared-end fitting was installed to the pump. For clearance issues, I then installed a female-to-male 90-degree adapter to the pump's fitting. The T-fitting on the left cylinder head was then connected to the pump's 90-degree adapter with -4 hose fitted with a 90-degree hose end at each end. This will allow air to be burped out as the water pump returns coolant to the radiator. All -4 hose, fittings and hose ends were sourced from Holley's Earl's Plumbing divi- sion. The 90-degree female/male adapter was supplied by Summit Racing (Fragola 498102BL). The -8 to -4 adapter at the water pump is an XRP unit. LIFTERS Our COMP hydraulic link-bar roller lifters P/N 8957-16, featuring a diameter of 0.842 inches, were soaked in 5W-30 COMP break- in oil overnight before installation. Note that when installing link-bar lifters, pay attention to the orientation of the link bar (an arrow indicates up). As noted in Part I of this build article, our lifter bore clearance is 0.0015 inches. CYLINDER HEADS As noted in Part I, for this build we chose AFR (Air Flow Research) LS3-style Mon- goose heads, P/N 1840. Features include 69cc combustion chambers and 260cc intake runner volume. The heads are 100% CNC machined, including combustion chamber, intake and exhaust ports. Valve angle is 12 degrees. PAC Racing springs were installed (1.270- inch OD hydraulic roller dual springs rated at a maximum rpm of 7,000-7,200). Full specs are listed in our previous Part I article. PRECISION ENGINE The Fluidampr crank balancer was smoothly drawn onto the crank snout and is secured with an ARP crank bolt. I installed timing tape to the damper, with the pointer aligned with zero at No. 1 cylinder TDC. Our COMP Cams hydraulic roller rockers feature a diameter of 0.842" and are link bar connected. We soaked the lifters in break-in oil a day prior to installation. The AFR Mongoose LS3 heads feature a unique 2.155" rocker stand bolt hole spacing, requiring rockers that are paired together on sliding/adjustable shafts, or by using a unique rocker stand made for us by Harland Sharp. Our head stud kit from ARP features the following stud sizes per head: QTY (EA HEAD) THREAD (LOWER/UPPER) O/A LENGTH 8................................... 7/16" X 14 / 7/16 X 20.................................. 3-1/2" 2................................... 7/16" X 14 / 7/16 X 20.................................. 3-5/8" 4................................... 3/8" X 16 / 3/8 X 24...................................... 2-1/4" 4.................................... M8 X 1.25 / 5/16 X 24................................... 70mm 5.................................... M8 X 1.25 / 5/16 X 24................................... 65mm

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