July '16

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JULY 2016 PRECISION ENGINE 7 PRECISION ENGINE studs have been pre-installed to the head deck) takes a bit of patience due to limited finger access in the lifter valley windows. I used a hemostat to slip the shouldered washers onto the studs, making sure that the shoulder registers into the hole. I also used a hemostat to locate the nut, and gingerly began to rotate the nut onto each stud with one finger. This was done with the engine block rotated to orient the head deck perpendicular to the floor, with the lifters parallel to the floor. This makes access a bit easier, but use caution because if you rotate too far toward the floor, the lifters can slide out of their bores. Once all four of these nuts were threaded onto their studs. I used a 1/4-inch-drive Mac Tools digital torque wrench and a 3/8-inch torque wrench extension that adds 2 inches to the effective length of the torque wrench. The 8mm nuts require a value of 22 foot- pounds. Because of the added length of the extension, I set the torque wrench at 19.06 foot-pounds in order to achieve an actual 22 foot-pounds. ROCKERS Rocker arm whiz Randy Becker from Har- land Sharp visited my shop with rockers and pedestals and shims to determine the optimum setup for the Trick Flow L92/ LS3 heads. After a bit of test-fitting, he determined that the SL927 rockers (intakes feature an offset) require a rocker pedestal height of 0.0700 inches in order to obtain proper sweep contact between the rocker roller tip and the valve tips. Becker then machined a set of pedes- tals to our required height. The machined billet rocker arms feature a 1.7:1 ratio. The supplied 8mm socket head cap screws are torqued to 22 foot-pounds. Note: Whenever installing LS rocker arm bolts, be aware that all intake rocker arm bolt threads must be coated with a sealing compound such as Teflon thread paste, since the threaded holes in the heads are open to intake ports. PUSHRODS During test-fitting, I swapped out the left cylinder head's number 1 intake and exhaust springs for light checking springs. After bringing number 1 piston to TDC and with number 1 intake and exhaust cam lobes on their base circles, I installed the head with an MLS head gasket, installed an adjustable checking pushrod and a pair of our Harland Sharp roller rockers. At zero lash, pushrod length measured 7.649 inches. Morel recommends a lifter preload of 0.045-0.050 inches, so max- imum pushrod length would be 7.699 inches. Since pushrods are available in increments of 0.025 inches, I ordered a set of 5/16-inch chromoly pushrods with 0.080-inch wall thickness at a length of 7.700 inches from Trend Performance. Trick Flow actually recommends a length of 7.700 inches with its 255cc LS3 heads, but we always measure to verify length. By the way, I also ordered a few pushrod cleaning brushes, which are handy when cleaning new pushrods to eliminate any manufacturing particles that may be present inside the oil passage. NEXT... Next time, we'll discuss the final engine assembly and see how she does on the dyno. MIKE MAVRIGIAN owns and operates Birchwood Automotive in Creston, Ohio, where he builds custom engines, street rods and performs vehicle res- torations. He has written thou- sands of technical articles, as well as nine books on automotive technology during the past 30 years. Mike can be reached at 330-435-6347 or Visit Birchwood's website at www.birchwood- Once pushrod lengths were determined and with pushrods installed, all rocker bolts were tightened to 22 foot-pounds. Note that LS cylinder head intake rocker bolt holes are open to intake runners, so thread sealant is required on all intake rocker bolt threads. The most exciting thing in air cleaners... well, since the air cleaner! cleaner! ®

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