||XIM controller and harness
||shaft rocker arm system, 1.8:1 ratio
|II Much Fabrication
||rocker cover breather and catch can, alternator spacer, remove FAST eDIST, and install FAST XIM and new harness
||sheetmetal rocker covers, 8mm primary wires
|Mike Norris Motorsports
||labor, dyno testing/tuning, billet fuel rails, LS3 injectors: 39 lb/hr (at 60 psi)
||10W30 synthetic oil
|Scoggin-Dickey Performance Center
||SD 8801 CNC L92 cylinder heads, 65cc combustion chambers, Manley Race-Flo series stainless steel valves: 2.165-inch intake; 1.590-inch exhaust, S-D/Patriot double springs: 1.80-inch installed height; closed pressure: 135 pounds; 1.15-inch compressed height, open pressure: 375 pounds; titanium valvespring retainers, SD 0121 hydraulic camshaft, 92mm throttle body, L76 intake manifold, and Cometic MLS head gaskets.
|GM ASA Cam
|Duration at 0.050:
||Intake 226 degrees
||Duration at 0.050:
||Intake 226.2 degrees
||Intake 0.525 inch
||Intake 0.610 inch
The engine had a small but persistent oil leak at the rear of the block. The head/intake manifold swap story revealed the origin: Both of the rear intake manifold bolts were missing. John Parsons is an engineer/hot rodder/upscale car builder who surmised that there may also be an internal pressure problem so he machined a rocker cover breather system and fabricated the corresponding overflow canister. The catch can end goes into the intake manifold, the breather side (that uses the original breather opening) on the tightly sealed Moroso sheetmetal rocker cover issues into K&N air intake tract. Primary ignition wires are solid-core 8mm Moroso. Parsons also fabbed a 1-inch spacer to move the alternator outward so that it would clear the end of the taller Moroso rocker cover).
Regarding a persistent engine misfire at proximately 4,500 rpm, he removed the early (and sometimes problematic) FAST eDIST module and installed a more modern FAST XIM box (thank you David Page) in its place. Then, all power and ground circuits were rewired. Parsons: “The actual problem with the original stuff was a badly frayed crank signal wire.” All of this conspired to make the engine cranking sequence way too long and the engine difficult (farting, backfiring, and the like) to start when cold. The new XIM module was the cure.
“The insulation was cracked and missing altogether in some spots. Worse, it was wound around the ground wire for the signal—a real mess. I redid the power and ground circuits so they come directly off the battery as recommended by FAST. Problem solved.”
Base 454 Runs
The old combo paired the LS6...
The old combo paired the LS6 intake manifold with 36-lb/hr injectors (the smaller of the two) originally meant for a Buick Grand National. One for the L92 is from an LS3 and rated at 39 lb/hr. Fitting them to the Holden L76 (or FAST) intake manifold requires O-rings of a different size. Thus, the difference of inside diameters on the LS6/FAST 0.540-inch injector boss and the LS2, LS3, LS7, and L76 0.565-inch boss creates a sizable vacuum leak. You cannot swap the lower injector O-rings for stock late-model pieces as the inside diameter of the manifold bung is also different and will result in escaping vacuum.
Intake runners of the LS6...
Intake runners of the LS6 intake (left) have more of a hump than the L76. The undersides look nothing alike, nor does the throttle body attachment point. Norris also installed the cable-operated 92mm throttle body in place of the 85mm one in the original combo and modified the throttle cable bracket to accept the Lokar cable attachment.
Surely there were nonswap-related...
Surely there were nonswap-related snags as well. The original fan controller became inconsistent, so Norris applied relays to make it work properly. He went from a stand-alone controller, with its own temperature probe and only one relay, to this three-relay setup with the FAST XFI and Vintage Air A/C switch to control the fans. The middle and righthand relays are for each fan. This way, there is not so much amperage going through one relay and both fans, especially when the fans engage on start-up. Originally, the relay on the left used to turn on the fans when the A/C was engaged. This relay actuates it when the A/C compressor sees the voltage to turn it on and supplies a ground for the other two relays.
Norris: “This [XIM spark curve]...
Norris: “This [XIM spark curve] is typical. Final timing is 18-20 degrees at idle [800 rpm] to give her a little more torque for better idle quality. From there, it is 24 at 2,000, 28 at 2,400, 29 from 2,800-3,600, 28 at 4,000, 27 at 4,440-4,800, 28 at 5,200, and 29 from 5,600-6,400. This allows for a smooth transition under hard acceleration and takes into account the loads preparing to go through the peak torque areas and ward off spark knock. After that, the timing ramps up for the best horsepower. At cruise rpm with a little load, timing is in the 34- to 36-degree area.”