7. To endure the rigors of high-RPM and the increased valvespring pressure of the 416, LME opts for a JP Performance billet double-roller timing set. It has multiple keyways cutouts on the crank gear for up to 8 degrees of cam advance or retard.
8. Using a degree wheel, LME verified the installed centerline of the camshaft. It was advanced two degrees to help bulk up low-end torque.
9. Since a stock LS3 utilizes a single-roller timing set, fitting an aftermarket double roller set requires grinding the back of the timing cover for clearance. LME made quick work of this process on its CNC machine.
10. The stock LS3 oil system is already plenty stout, but the LME 416 ramps up the oil flow even more with a Melling high-volume pump. Before installing it, LME radiused the outlet and grinded down all the sharp edges to improve flow.
11. All the cubic inches in the world don’t mean squat without a set of high-flow cylinder heads, and the factory LS3 castings are among the greatest production small-block heads ever built. GM engineers improved upon the already potent cathedral-port LS1 heads by pushing the pushrod passages over to the side, freeing up space for a larger rectangular port with a raised entrance.
12. To maintain valve control at high RPM, LME fitted the heads with PAC dual valvesprings that feature 170 pounds of seat pressure and 430 pounds of open pressure. They’re anchored in place by lightweight titanium retainers to keep valvetrain mass and valve float to a minimum.
13. After a trip through LME’s proprietary CNC program, the factory LS3 cylinder heads flow 365 cfm through the intake ports at 0.630-inch lift. That puts them right on par with the stock LS7 heads at a fraction of the cost.
14. The CNC porting bumps the exhaust port flow up to 235 cfm. Although the LS3 head castings have been criticized for having poor exhaust flow relative to the intake ports, 235 cfm is still right on par with a big-port Gen I small-block Chevy head. Likewise, using a slightly longer exhaust duration on the camshaft addresses the situation nicely.
15. LME’s ported LS3 heads retain the factory 2.165-inch hollow-stem intake valve and 1.600-inch stainless steel exhaust valves. They received a three-angle cut, and LME blended them into the stock 70cc combustion chambers.
16. Sending the lobe lift to the rocker arms are GM LS7 hydraulic roller lifters and 7.400-inch Trick Flow pushrods. The GM hydraulic lifters perform more like solid roller lifters, and can maintain valvetrain stability past 7,000 rpm.
17. In order to tighten up the quench clearance as much as possible, LME sets the pistons to 0.010-inch “out of the hole” and utilizes 0.048-inch-thick GM head gaskets. This yields a 0.038-inch quench clearance. Tighter quench not only produces more horsepower, it also reduces the potential for detonation by improving the homogenization of the air/fuel mixture.
18. Although head studs offer the ultimate in clamping force, head bolts are more than adequate for a naturally aspirated combination like the LME 416. The ARP bolts were torqued down to 70 lb-ft.
19. The LME 416 uses the stock LS3 rocker arms, but with a twist. To enhance longevity under increased valvespring pressure and higher RPM, LME fortified the stock rockers with a Comp Cams trunnion conversion kit. The trick setup replaces the stock pivots with heavy-duty rocker arm trunnions and bearings. At $135, the conversion is a heck of a lot cheaper than a set of aftermarket rocker arms.
20. Since the cylinder heads can only flow as much as an intake manifold will allow, LME matched up its ported LS3 castings with a high-flow Fast LSXR manifold. It features a 102mm inlet, which was matched to a Nick Williams billet throttle body of the same diameter.
21. A testament to the efficiency of the LS3 cylinder heads, the 416 required just 28 degrees of ignition advance on LME’s Superflow dyno. With the air/fuel ratio dialed in at 11.8:1, the motor kicked out 622 hp at 6,200 rpm and 574 lb-ft at 5,250 rpm.