October '19

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42 THE SHOP OCTOBER 2019 BUILDING THE Nighthawk II LS PRECISION ENGINE flush to both the raised and relieved surfaces on the valley plate, allowing a seal between the adapter's O-ring and the valley plate. I had considered fabricating an alu- minum stand-off tubular bung to the valley plate (with the center of the tube tapped for 16mm x 1.5 thread), which would have required weld dressing and re-anodizing the valley plate. The Holley valley plate was installed using an OE-style LSX valley plate gasket and ARP 8mm x 1.25 x 20mm 12-point stainless bolts and flat washers, torqued to 18 foot-pounds. The oil pressure sender adapter block mounts with a pair of 8mm x 1.25 socket-head cap screws. All bolt threads were lightly coated with ARP assembly lube. OIL CONTROL The oiling system features a Melling oil pump 10296 (high-volume/high-pressure), Holley LS oil pan 302-131BK and pickup and an OE-approach filter mount at the oil pan. The left side of the block features two -10 AN threaded ports (out at front and in at rear) if a remote oil filter is to be mounted. Since we installed the filter at the standard pan location, we installed a pair of -10 AN straight-thread O-ring sealed plugs in the block, using a Holley-supplied NOS Sniper hex-head plug at the front (oil out) port, and a -10 plug that features an internal hex drive at the rear (oil in) port. A plug with an internal hex is required because an external hex won't provide wrench access at the rear port location, which is slightly recessed in the block casting. Our -10 plug with internal hex requires a 7/16-inch hex bit. The Melling pump is equipped with a red high-pressure relief spring. Since Dart's Dick Maskin noted that the block's oiling efficiency is such that a standard pressure is preferred, I swapped out the red high- pressure spring with the included blue standard-pressure spring. The Melling oil pump is secured with four ARP 661-1007 8mm bolts torqued to 18 foot-pounds. I pre-oiled and primed the pump prior to mounting, and applied oil to the crank snout-mounted, wide-tooth drive gear prior to installation. Our Holley oil pan is supplied with a pickup tube/screen assembly. The tube mounts to the oil pump using Holley's brown O-ring or Melling's black O-ring (Melling supplies black and green O-rings, depending on the design of the tube neckā€”per the source of the pickup, the nipple may be stepped, tapered or straight, which will dictate which O-ring is correct). The tube is secured to the pump with a single 6mm x 1.0 x 20mm bolt (Loctite 242 and torque at 106 inch-pounds). Caution! If the bolt is longer than 25mm, the tip may contact the timing chain. Also, make sure that the pickup mounting tab seats flush with the pump mounting surface. The challenge was to secure the pickup tube's support bracket to the No. 4 main cap. The pickup is designed for use on an OE LS block, sharing a main cap bolt at the No. 4 cap. However, the Dart main cap bolts are not in the same left-to-right centerlines as the OE design, resulting in the tube bracket foot hanging outboard of the No. 4 main cap's left inboard bolt. The remedy was to cut off the sup- port bracket and fabricate a new vertical L-bracket that allows securing the tube to the No. 4 main cap's center-located 5/16- inch x 18 female threaded hole (each main cap features this 5/16-inch hole to allow the use of a dead-blow slide hammer for easy cap removal). The new bracket, with the vertical run at 3.25 inches long, was then TIG-welded to the tube. The short horizontal leg of the bracket was then secured to the No. 4 main cap with a 5/16-inch x 18 x 1.5-inch stud with 271 thread locker and a self-locking Stover nut, torqued to 20 foot-pounds. Since the Dart SHP LS Next block fea- Since the oil pickup supplied with the Holley oil pan was designed for its support bracket to attach to an OE main cap bolt location, we modified the bracket, mount- ing it to a main cap's 5/16-inch x 18 hole (all of the caps feature a center-located 5/16-inch hole designed to use a body puller during main cap removal). This made securing the pickup tube's support bracket a breeze. I installed a 5/16-inch stud in the main cap (using Loctite 271 threadlocker). With the bracket attached, I secured it with a locking nut. The Fel-Pro MLS head gaskets feature a 4.170-inch gasket bore to accommodate our bore size and the 23-bolt fastener pattern. Like all LS platforms, the lifters must be installed prior to installing the heads. Primary studs are 7/16 inches. Outboard studs are 3/8 inches. Far-inboard pinch bolt studs are 8mm, and the extra studs that are first installed to the head decks and pass into the lifter valley are 8mm/5/16-inch.

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