1. For the top end, we selected LS7 Pro Elite heads from RHS. These 355-T6 aluminum units come fully assembled with lightweight Manley valves.
4. Note the rounded mounting surface for the valve stem lock. While I haven’t seen it specified, it makes sense that the radius avoids creating a stress riser better than a square-edged cut would.
2. The RHS heads are also CNC-ported. There’s still a lot to be said for the line-of-sight approach to flow, and there’s clearly plenty of that here.
7. Since removing the valves damages the seals, new ones were installed when the valves were put back in. The numbers denote the spring heights with the valves installed.
5. Here’s the mating surface of the valve after lapping. The frosted grey area is the area that’s been lapped.
3. The first step in our head work was to disassemble the heads and “lap” the valves into their seats in the combustion chamber. The heads were then surfaced, to ensure a true surface where they mate to the block.
8. A pneumatic tool is used to compress the valve stems and slip the retainers into place.
11. Unlike factory LS heads, the RHS units feature a six-bolt configuration. Mated to an RHS (or LSX) block with the anchor points for those extra bolts, this arrangement offers significantly increased clamping force, a plus on boosted engines.
6. Good springs are crucial, especially at high rpm. The dual-spring feature is added insurance: If one of the two breaks, there’s still another to keep the valve from dropping.
14. With the cam in place, we dropped in the Comp hydraulic roller lifters and installed a factory lifter tray to keep them in place. The lifters had previously been soaked in solvent to prepare them for installation.
12. Comp Cams provided the cam, which features 0.605-/0.615-inch lift, 238-/248-degrees duration, and a 112-degree LSA. After being lubed, it was slipped carefully into its bearings in the block.
9. After machining, the heads were cc’d to check the size of the combustion chamber. In our case, we wanted to stick with the factory 10.7:1 ratio.
16. In addition to providing more stability than traditional stud-mounted units, the aluminum Comp shaft rockers come drilled with oiling holes to keep everything lubricated.
15. The next order of business was to install the base for our Comp 1.8-ratio shaft-mounted roller rockers. Part of the installation process was measuring for the optimum mounting height, then shimming the base.
13. After the Comp Cams timing set was installed, it was adjusted to degree in the cam. The cam gear on the Comp set uses a screw on an eccentric to give some adjustment without having to disassemble everything.
19. We paired the LSXR with one of FAST’s beautifully machined 102mm Big Mouth throttle bodies. It’s every bit as big as it looks it the picture.
10. After putting a multilayer steel head gasket in place, the heads slipped onto their ARP studs. The fasteners were then torqued down, followed by the top cover.
17. Once the bases were shimmed and torqued in place, we could install the pushrods and bolt down the rocker shafts.
23. To install the assembled rails, we aligned the tops of the injectors with their respective holes in the underside of each rail, then pushed the rails down, essentially “plugging in” the injectors. After that, we indexed the fuel-rail mounting brackets with their holes in the intake, screwed them down, and put the crossover in place.
20. While the factory Corvette throttle body uses drive-by-wire actuation, the FAST unit is cable-operated. That means you’ll need to add a cable to your pedal assembly and, more than likely, change out your engine computer.
21. With their O-rings lubricated, the eight FAST injectors slipped easily into place in the intake. Thanks to a healthy flow rating of 65-lb/hr, they should provide plenty of fuel to feed our big-inch stroker.
18. FAST’s LSXR intake is made of lightweight polymer. The LS7 version we used features raised ports, removable runners, and a 102mm throttle-body opening.
24. The height of our valvetrain kept us from using stock valve covers, so we used this set of cast-aluminum covers instead. They came in a black-crinkle finish, with oil-control baffles already installed.
22. Along with the injectors, FAST supplied a set of red-anodized fuel rails and an -8 AN fuel crossover. We used an aluminum AN wrench to ensure we didn’t scratch up the anodized fittings.
25. Here’s a shot of one of the covers as installed. As you can see, they come with mounting studs that retain the factory centerbolt mounting arrangement.
26. Done. Our LS3 stroker is now officially together, and ready to hit the dyno.