Rated by 21 members
Written by David Schnitzer from NYMCGP
- Picture 1: The package from ZZPerformance.
- Picture 2: Untouched engine bay right after popping the hood.
- Picture 3: Complete spread of all included parts: Six 1.80 ratio rockers (top row), Six 1.85 ratio rockers (bottom row), 2 modified aluminum pedestals, 12 new torque to yield rocker bolts, and 2 new valve cover gaskets. [Note: This dual ratio has proven to be the optimal setup for the GT’s L36 Engine, whereby the GTP’s modified ratio is typically 1.90 all around.]
- Picture 4: Removed plastic engine cover and replaced oil fill cap. Removed front engine mount dog bones. Disconnected negative battery terminal.
- Picture 5: Removed spark plug wires and grey harness from bottom of ignition module.
- Picture 6: To remove the black cast iron coil pack mount from engine block I had to remove 3 nuts, (and a fourth nut to take off the alternator bracket), one of the 3 nuts came right off, but 2 were a bitch because two of the bolts stuck out an extra 3 inches, so I couldn’t use my regular sockets. Instead, I had to use an open ended wrench at a VERY awkward angle to carefully loosen them so I could remove them by hand. Note the position of the ground wire on bottom most bolt.
- Picture 7: Removed entire cast iron ignition module mount, exposing the left side of the front valve cover.
- Picture 8: Removed six valve cover bolts using a 3/8” socket and extension. Remove front valve cover.
- Picture 9: Side-by-side comparison of the underside of modified 1.85 rocker (left) vs. stock 1.6 rocker (right). You can clearly see how the pushrod seat has been moved down, closer to the fulcrum. This change in geometry allows the valve to open and close quicker then stock increasing effective duration.
- Picture 10: Unbolted all 6 rocker studs using 3/8” socket, and removed the stock aluminum pedestal.
- Picture 11: Placed modified aluminum pedestal in position, and started installing modified rockers by threading new bolts by hand.
- Picture 12: 1.85 rockers installed on intake (above spark plug), 1.80 rockers installed on exhaust (above exhaust manifold). Rocker bolts were tightened to 11ft-lbs, then an additional ¼ turn. Torque wrench pictured.
- Picture 13: Shot of the inside of the valve cover, with the new black gasket installed.
- Picture 14: Now for the rears: I opened the drivers door and began rocking the car forward and back to build up some momentum, then when the car was very far forward, I quickly hit the E-brake to hold it there. This rotated the engine forward so there was a little more access to the rear valve cover. I took a ratchet and removed 3 bolts that held on a tubular black metal bracket that was blocking the top of the valve cover. After disconnecting several wiring harnesses and vacuum tubes and pushing a lot of wiring out of the way, the rear valve cover was able to be removed. It took a LOT of maneuvering to get it out. Smart planning on the part of GM designing the valve cover and bolts so that they can not separate, if they were not like that, it would have been tough preventing bolts from falling down. I started removing the rear rockers from left to right. The original orange valve cover gasket is visible.
- Picture 15: Picture of rear bank with all rockers removed.
- Picture 16: Same shot, close up. You can clearly see the pushrods sticking up.
- Picture 17 & Picture 18: Pictures a friend took of me as I torqued the rocker bolts.
- Picture 19: After the rear valve cover was replaced and the bolts were tightened so they were snug, I began reassembly. All wiring harnesses, clips, vacuum tubes that were disconnected or relocated to remove the rear valve cover were replaced. In this shot, you can see the cast iron ignition module mount halfway installed. After this shot was taken I reinstalled the alternator bracket, ignition harness, dog bones, spark plugs, and negative battery terminal. I then starred at the engine bay for 5 minutes looking for anything I forgot. Once I was confident that the job was done, I started the engine up and listened for any unusual sounds. All sounded good, and when I took the car out for a drive I had a car that pulled MUCH harder on the top end!
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