Edelbrock LT1 Aluminum Cylinder Heads - Killer Whale, Part 4

With the driver-side head... 

   

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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.

The combustion chambers in... 

   

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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!

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.

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.

Working on an LT1 requires...        read full caption Working on an LT1 requires a lot of manpower. But when you run out of patience and old beer, the natives tend to get restless and take matters into their own hands. Here, the J&T crew decides to help "Big Tom" speed things up at 8 p.m.	Looking at the Edelbrock intake,...        read full caption Looking at the Edelbrock intake, you will immediately notice the plenum is raised. Unlike the factory piece, the raised design slightly increases runner length and creates an air gap under the plenum, allowing air to pass through and cool this area for more performance. It also makes it easier to cool the car down in between rounds, as you can put some ice in there.	It should be noted that LT1s...        read full caption It should be noted that LT1s use torque-to-yield head bolts from the factory. We decided to use conventional bolts, so we ordered a new set from the local dealer intended for a traditional small-block and cranked them down to 75 lb-ft each. At this point, things are starting to look pretty.
At the back of each LT1 cylinder...        read full caption At the back of each LT1 cylinder head is a steam fitting. Because the lT1 is a reverse-cooled engine, GM used a crossover tube to collect steam that typically settles at the rear and allow it to settle back into an aqueous state when it flows back to the throttle body.	"Big Tom" uses a liberal amount...        read full caption "Big Tom" uses a liberal amount of silicones gasket maker to seal the ends of the intake manifold instead of using a conventional rubber seal. This ensures a leak-free fit because it can get into every nook and cranny.	Installing the intake manifold...        read full caption Installing the intake manifold is as simple as replacing the original one. All the sensors and fuel injectors directly transfer over and bolt right into place. We also transferred the 52mm Edelbrock throttle body, and as expected, it went on without a hitch.
After checking the rocker...        read full caption After checking the rocker arm clearance, we were ready to install our valve covers back into place. Thankfully, no modifications were required to the bolt stands for the Comp Cams roller rockers to clear.	Sitting pretty, sitting proud....        read full caption Sitting pretty, sitting proud. From our previous best of 14.405 at 92.81 mph, we were now looking at an incredible 13.903 at 96.55 mph with a 2.022 short time. That's a gain of .501 in e.t. and 3.74 mph on the top end.