Edelbrock Cylinder Heads - Killer Whale, Part 4

We Gain Half A Second And Nearlyfour Mph At The Track By Adding Edelbrock's Performer Lt1 Top Half To Our Caprice.

Vinnie The Hitman Jul 1, 2008 0 Comment(s)
Sucp_0807_20_z 1992_chevy_lt1 Driver_side_head_off 2/22

With the driver-side head off, you can take a gander at our factory hypereutectic pistons. There are four valve reliefs from the factory, so it's good to know that should we upgrade the cam for more lift, there's some room. The passenger side is more difficult to work around because of the air-conditioning system that tends to get in the way of everything.

We left the stock camshaft in place. It has a torque-oriented profile for the iron-headed LT1, with its 260-horsepower rating. This cam checks in with an advertised duration of 205/207 degrees, and total lift with the 1.5 rockers is .447/.459 for the intake and exhaust, respectively. LSA is at 117 degrees, and compared to earlier '94-95 LT1s, our cam specs are milder on our '96, no doubt a concession to OBD-II. We'll stick with it for now to see how the intake and heads work out by themselves. We'll address this cam situation later.

Looking for an LT1 expert to install our new top half wasn't as easy as it used to be. Quite frankly, everyone is now involved with LSX cars, so finding a good shop is no longer a walk through the small-block park. However, experienced LT1 technicians can still be found within the veteran ranks of the GM performance movement, so we were happy to find John Moundros of J&T Auto in Huntington Station, New York, in our Rolodex.

Once there, we quickly got to work as Tom O'Sullivan (aka "Big Tom") started turning the wrenches while we shot the pictures. After a full day of work, we finished the installation and promptly took our cop car back to Raceway Park in Old Bridge Township, New Jersey. Once there, we quickly cooled our car down, slapped on the Nitto Drag radials, and went for broke. With the car staged shallow and stalled on the converter, we mashed the gas and were rewarded with an incredible 13.903 at 96.55 mph on the first pass. This represents a drop of five-tenths (.501, to be exact) and a gain of 3.74 mph from our previous best of 14.405 at 92.81 mph.

Sucp_0807_23_z 1992_chevy_lt1 Edelbrock_heads 3/22

The combustion chambers in the Edelbrock heads (right) are less shrouded than the factory castings (left) for improved breathing during low- to midlift valve events. This promotes and, of course, better cylinder filling and evacuation during part-throttle use, which helps fuel economy and emissions. Of course, the ultimate benefit that comes with increased efficiency is more power.

Excited and very satisfied with our all-motor performance, we then armed the Zex nitrous system and made another run. This time around, we launched at the same rpm and left with a 1.76 short time and dropped our e.t. to an incredible 12.855 at 101.44 mph. Previously, our best time with the stock heads and intake manifold with the nitrous armed was 13.522 at 98.70 mph, so our gains were substantial, but the car hit the rev limiter at about 1,200 feet out and rolled through the traps. With the 27.76-inch tire height of the 275-60-15 Nitto drag radials and the 3.73 gears, we should have had enough room to make a full pass, but with the higher-stall torque converter and the relatively low 5,400-rpm limit of the factory PCM, we just couldn't go any faster. It's too darn bad, because we felt there was at least another .020 in e.t. and 1 mph in it.

Now that we're staring at a stack of wrinkly old timeslips, it's time to start optimizing our setup. In our next installment, we'll look at some other internal engine mods and try to unlock some hidden potential in that aluminum-cased brainbox sitting in the engine compartment. Long live the Cop-rice!

Sucp_0807_31_z 1992_chevy_lt1 Rocker_arm_adjustments 4/22

The rocker's arms are then adjusted. We like to tackle this by making sure we adjust the valves while the lifter is on the lobe's backside. To do this, rotate the engine until the cylinder you're working on is about to open its exhaust valve. Now, adjust the exhaust valve. After pushrod contact, turn the adjuster about one-half to three-quarters of a turn and lock down the polylock.

Sucp_0807_32_z 1992_chevy_lt1 Engine_fillup 5/22

With the engine assembly complete, it was time to fill the engine up with fresh fluids. Here, "Big Tom" uses an incredibly fancy filling system that purges all traces of air important, because any air pocket in the system will cause teh car to overheat, damaging the engine, and in a worst-case scenario cracking hard parts.


Comp Cams
Memphis, TN 38118




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