Although the Camaro had already been treated to ported heads with 2.02/1.60-inch valves in place of the
2.00/1.55-stock pieces, the new intake, along with more aggressive cam profiling, seemed to warrant yet another
head upgrade. This time, they installed 2.07/1.60-inch Ferrea stainless valves in extensively ported castings,
which had also been milled 0.030-inch for increased compression.
Cylinder Heads
Since the intake manifold had improved breathing, the team felt that further head modifications
were warranted. Fresh cylinder head castings were fitted with larger 2.07–inch intake valves, while the exhausts
received the 1.60–inch valves used in the previous heads. After three weeks of eight hour days, cylinder head
instructors Greg Good and Casey Snyder, with the help of many students, developed intake ports that flowed 324
cfm at 0.650–inch lift–the previous heads had topped out at 288 cfm. (See the accompanying chart for complete
flow test results.) The castings were then milled 0.030 inch, removing 4 cc from each combustion chamber to
bump compression from 10.1:1 to 10.4:1 (though this was later negated by cutting valve reliefs in the pistons).
The increase in airflow prompted pilot Massingill to move his shift points from 6,800 to 7,000
rpm. With engine speeds above 6,800 rpm, it is imperative that lifter plunger preload does not exceed 0.015
inch. If adjustments are necessary, shims can be used between the rocker stands and the head casting. The
revised cylinder heads improved performance to 11.14 at 122.90 mph.
Those familiar with the LS1 probably raised an eyebrow at the 241° duration and 0.615–lift of the solid cam,
but the students had anticipated the big stick, and cut valve reliefs in the stock pistons using an Iskenderian
tool. It fits into the valve guide in the head, then the head is positioned on the block, and the tool is turned
with a drill. The S.A.M. team says it works like a charm.
Camshafts
Now that the heads were flowing more, the team stepped up the cam profiling to match them.
In anticipation, Instructor Patrick Topolinski had the students cut valve reliefs in the stock pistons while
the heads were off, using a special tool from Iskenderian. Student Chris Grimes has been overseeing the cam
changes since the first, back when the Camaro was in the low 12s. That swap consisted of a hydraulic roller,
similar in design to the stock cam but ground for 224 degrees duration at 0.050–inch lift and 0.533–inch lift
intake/exhaust on a 113–degree lobe seperation. Comp Cams ground the LS1 blank for 224/232 duration at 0.050
and 0.590/0.600–inch lift, while maintaining the 113–degree lobe separation angle. Again, Massingill raised
his shifts points, this time to an astonishing 7,200 rpm, and the Camaro responded with an 11.00 at 123.60.
The performance increase was substantial, but the high rpm level was well beyond safe for
hydraulic roller lifters. For this reason, the team switched to a solid roller. Of course, that afforded
more profile alterations, so this stick, custom–made by LSM Systems Engineering, was ground for 234/241
degrees duration at 0.050 and 0.615/0.605–inch lift, now on a 112–degree lobe separation angle.
Going with a solid cam required an adjustable valvetrain, so the stock rockers were retired
in favor of Jesel shaft–mounted 1.7:1 ratio arms. Since the stock valve covers would not clear the height
of the Jesel rockers, the students designed billet aluminum spacers to fit between the heads and the covers
and had a CNC shop mill them. (S.A.M. now offers them to the public.) The added valve cover height
necessitated longer spark plug wires, which Moroso custom–made with an extra 2 inches of length. This
valvetrain upgrade was the demon tweak that pushed the Camaro into the hallowed 10-second realm (10.90 at
124.50 mph).
With the increased airflow, rpm levels were far exceeding the generally accepted "safe" operating range of
the hydraulic roller lifters. A change to solid roller required adjustable rocker arms, sourced from Jesel.
However, the increased height of the rocker assemblies would not clear the stock valve covers, so the team
machined aluminum spacers to provide the necessary clearance. This in turn required custom–length spark–plug
wires to reach from the valvecover–mounted coils to the plugs.
