July '16

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2 PRECISION ENGINE JULY 2016 PRECISION ENGINE CYLINDER HEAD INSTALLATION Dart's Dick Maskin recommends the fol- lowing cylinder head installation proce- dure: Test-fit all 7/16-inch head studs to check thread depth engagement. If the upper portion of the 7/16-14 threads disappear below deck, and the unthreaded portion of the studs meets the deck surface, this may subject the deck to excess stress, as the unthreaded portion of the studs are forced into the deck threads. In this case, the stud depth in the block needs to be adjusted by dropping a ball bearing into the blind hole and reinstalling the stud. Required ball diameter can range from 1/16 to 3/16 inches. This is only nec- essary if your studs feature flat-bottom tips. If the studs feature a tip extension (bull- nose, etc.) this shouldn't be necessary. The goal is to make sure that the upper area of the stud's lower threaded in-block section doesn't engage at or deeper than the block deck surface. If the 7/16-14 threads disappear below deck, even though the studs will be installed finger-tight, when tightening the nuts, you stand a chance that the unthreaded shank area can dig into the top female threads in the block. Also, Maskin recommends using only CMD #3 high-pressure lubricant for nut- to-stud lubrication. In addition, he suggests soaking the upper fine threads of the 7/16- inch studs in muriatic acid (HCl–hydro- chloric acid) to eliminate the black coating. As a result of his extensive research, Maskin LS NEXT PROJECT Cylinder Heads • Trick Flow GenX, P/N TFS-3261T004-C01 • 255cc intake volume • CNC competition ported • 69cc CNC combustion chambers • 448-pound springs • Titanium retainers • 6-bolt • LS3 style with rectangular intake ports CYLINDER HEAD STUD KIT ARP offers a cylinder head stud kit specific to the 23-bolt LS-Next application. Each head utilizes the following studs: QTY LOWER THREAD UPPER THREAD O/A LENGTH WRENCH SIZE LOCATION 4 3/8-16 3/8-24 2 1/4" 1/2" OUTBOARD 5 8X1.25mm 5/16-24 65mm 3/8" INBOARD 4 8X1.25mm 5/16-24 70mm 3/8" "EXTRA*" 2 7/16-14 7/16-20 3 3/4" 5/8" LOWER CORNERS 8 7/16-14 7/16-20 3 1/2" 5/8" PRIMARY Male Hex Wrench Sizes to Drive Studs 3/8 STUDS 5/32" 8mm/5/16 STUDS 3mm 7/16 STUDS 3/16" *The four (per head) "extra" 8mm x 1.25 x 70mm studs thread into the bottom of the head and pass through bosses in the block, secured with 5/16 x 24 nuts and special shouldered flange washers. A 3mm hex wrench is required to drive (install/remove) these studs. Install all studs only finger-tight. Dart suggests applying Loctite 241 to the course threads, although this isn't necessary (although not a bad idea for the five 8mm studs that screw into the cylinder head deck). Note: When test-fitting the Trick Flow LS3 heads, I discovered that the four out- board bolt holes on the heads were originally drilled to 0.350-inches in diameter, likely to accommodate OE size 8mm bolts on a GM factory LSX block. In order to use the required 3/8-16 ARP studs for the Dart block, I enlarged these four holes on the outboard side of each head to 0.390 inches, which was no big deal. This provided a comfy fit for the 3/8-inch studs that the Dart block requires. Once the holes were drilled to the larger diameter, the upper and lower edges of each hole were lightly chamfered using a deburring tool. Our cylinder heads are Trick Flow aluminum, featuring generous 255cc intake runner vol- ume. Due to the LS3 design, intake ports are rectangular. Pay attention to head gasket orienta- tion. Each gasket is clearly labeled "FRONT." The right and left side gaskets are dedicated for position and are not interchangeable.

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