When we left this fat ol' mutt last month, its motor was fixed with the foundation for a spicier camshaft. A Crane rocker-arm kit (1.8:1, dual valvesprings, stouter pushrods, etc.) and the beginnings of a deep breathing apparatus (K&N cold-air intake and Bassani after-cat system) laid the groundwork for a Crane cam featuring more lift and duration than the stock camshaft. Although our Silverado is equipped with a 5.3L engine (325ci), this stick can also be applied to a 4.8, 5.7, or a 6.0L engine with similar results.
Roger Vinci specified the grind (HR-210/ 3241-2S-12 2A) because it works well with the stock LM7 aluminum cylinder heads (61.15cc combustion chambers, 9.5:1 compression ratio, 200cc intake-port volume, 70cc exhaust-port volume, 1.89-inch intake valve, 1.55-inch exhaust valve) and the OE cast iron exhaust manifolds that remain intact for the initial phases. This grind also promises compatibility with freer-breathing heads, tubular headers, high-flow catalytic converters, and the roots-type supercharger that will likely complete the final combination. With a 1.7:1-ratio rocker arm, the specs are 0.551-inch lift for both valves and 210/218 degrees of duration at 0.050-inch.
Ancillary equipment for the cam swap was Crane's adjustable dual-roller timing set (PN: 144984-1), including billet steel sprockets, oil pump spacers, and instal-lation hardware. This tough ensemble ensures that the timing gear will stay where it should be. Without it, the worst case would be that the cam slides back in the block, causing the lifters to hit the lobes next to them as well as the cam-bearing journals, chipping the lifters and the sides of the lobes. Further, the cam sprocket can be adjusted to retard or advance timing by five degrees, but Vinci's Greg Warner installed our camshaft straight up.
As you've noticed, gasoline prices have become a concern, notorious in some parts of the country. In mid-May, 93-octane was selling for $2.26 a gallon in central Florida; in southern California during the same period, we paid as much as $2.95 for 91, the highest rating available there. We wondered how this normally aspirated engine equipment would affect the overall picture. Without getting too involved, our strictly around-town numbers are something like 14 mpg; a mixture of super-slab and stoplights puts the tally a bit beyond 18, and that's without regard to the throttle. Of course, a large part of this has to do with the engine design; the stuff we put to it has simply magnified its superiority.
On the visceral side, the engine now has a loping idle that smoothes out some-what as the engine reaches operating temperature. It sounds like the old days, and elicits that same bad-boy emotion from a middle-age psyche and stirs some cayenne in the blood. As designed for mid- and upper-range response, the cam is a bit on the lazy side under normal throttle, but when you push the pedal halfway down, the engine zings. Mat the throttle and it goes right to six grand with a head-turning howl. Passing up a semi on a two-lane in the bug-blown, tar-black Florida night is no more difficult than popping a tallboy by the pool.
So far, the engine enhancements have provide these corrected maximum outputs: stock: 289.4 lb-ft, 236.7 hp; Crane rocker-arm kit: 299.6 lb-ft, 255.9 hp; K&N and Bassani exhaust: 318.9 lb-ft, 273.5 hp; Crane cam: 324.2 lb-ft, 304.7 hp. Next, well be looking for more low-end, as well as an increase in top-end performance with aftermarket cylinder heads, tube headers and high-flow catalytic converters. Think you can stay awake?
To pull the cam out, use the three water-pump bolts as a handle. Rotate the camshaft to push to lifters up into the bores. You can't feel this happening but a couple of turns will do the trick. Then slowly pull the cam out of the block, as not to nick the bearings. | 
Prep the Crane cam by washing it thoroughly to remove the packing grease. Run a brush down the middle of it for the same reason. Dry with compressed air. Apply drops of Crane break-in lube to the lobes and journals, working it in by hand. Using the three bolts as a handle again, insert the cam slowly into the block. Coat the retainer plate with a film of oil and install the bolts (as long as you can feel the ridge of the O-ring gasket, it's safe to reuse the original plate). Torque bolts to 22 lb-ft on iron block (18 lb-ft on aluminum one). | 
As the installation device for the new sprocket, use the old sprocket, centering it over the double-row unit and applying enough torque on the installation device to push it home... |
...Apply the Crane lube to all surfaces, including the thrust bearing (supplied with kit). | 
The double-roller cam gear has provision for advancing or retarding the camshaft simply by loosening the Allen screws and moving the sprocket accordingly... | 
...Secure the gear to the camshaft with red Loctite on the bolts and torque to 26 ft-lb... |
...Align the timing dots on the gears, and tighten the Allen timing-gear bolts by hand. Repeat the procedure. Note oil pump pick-up tube. | 
Clean the oil return hole (to the oil pump) and apply some sealer around it. Align the pump with the pick-up tube O-ring (use a mirror to verify the fit)... | 
...Install the provided shims behind the oil pump to gain the clearance needed for the extra width of the double roller chain. Attach the pick-up tube. |
Raise the truck again. Tighten the oil-pan bolts as well as the two bellhousing bolts previously loosened in order to drop the oil pan. | 
Replace the timing-gear cover, being sure to align the hole for the crank snout on either side. For an added measure of reliability, we replaced the crank bolt with a hefty ARP unit (PN: 234-2503) torqued to 250 ft-lb... | 
...Reinstall the rocker arms (tightening and bleeding the lifters down in the proper sequence), rocker covers, and coil packs. |
Vinci specified Champion RS12YC spark plugs (right). The OE Denso extended-reach platinum plugs have a 0.120-inch projection. The Champions are only 0.060-inch. Vinci favors them in the face of the increased combustion-chamber pressures of a modified engine. Warner gapped them at 0.040-inch. | | |