2006-2013 Chevrolet Corvette Z06 LS7 valve spring replacement (heads-on)

The LS7 valve spring service is preventive on any Z06 approaching 60,000 miles and mandatory on any car with confirmed spring failure symptoms: valve float on a data log, a cylinder failing leakdown into the exhaust or intake, or a lifter tick that develops under load. Perform a hot leakdown test on all eight cylinders and record the results before disassembly. Any cylinder above 10 percent leakdown into the exhaust indicates a bent valve, and heads-on spring replacement will not fix that; the head has to come off.

Disconnect the negative battery terminal. Remove the intake tube, throttle body, and the intake manifold. Cover the intake ports. Remove both valve covers (four bolts each) and the coil pack rails. Remove all eight spark plugs. Note the position of the ignition coil connectors so they return to the correct cylinders.

Remove the drive belt and, on the driver side of the crankshaft, fit a socket to the crank bolt. Rotate the crank clockwise to bring cylinder 1 to top dead center on the compression stroke; both intake and exhaust rocker tips will be free of tension and the timing mark on the front cover will align. Fit the air chuck adapter into the cylinder 1 spark plug hole. Apply 90 psi of shop air to hold the valves against their seats. If the air pushes the piston off TDC, the crank will spin and the air chuck will fire out of the plug hole. Lock the crank with a fixture or by putting the transmission in gear with the parking brake fully engaged before applying air.

Loosen the two intake and two exhaust rocker bolts on cylinder 1. Lift the rockers off the pedestal and set them in labeled positions; LS7 rockers are handed and must return to the exact valve they came off. Do not mix rockers between cylinders or between intake and exhaust positions.

Fit the on-vehicle valve spring compressor over the retainer. Compress the spring slowly and watch the keepers separate. Once the keepers loosen, use a magnetic pickup or bent-nose pliers to lift them out. Release the compressor. Lift off the retainer, the spring, and the spring seat if present. Slide the old valve stem seal off using a pick or seal removal tool.

Lubricate the new valve stem seal with clean engine oil and press it onto the guide by hand; never hammer. Set the new spring seat if the kit includes one. Fit the new spring and retainer. Compress with the tool. Seat both keeper halves into the retainer groove with grease as a temporary hold, then release the compressor slowly. Confirm the retainer is fully seated on the keepers before removing the tool. Any keeper that seats crooked will fire out at the first rev.

Complete both intake and both exhaust valves on cylinder 1. Release cylinder 1 air pressure. Rotate the crank to the next cylinder in the firing order (LS firing order 1-8-7-2-6-5-4-3). Pressurize that cylinder and repeat. Working the firing order minimizes the crank rotation between cylinders and keeps the disassembly organized.

Set each rocker back on the correct valve. Fit new rocker bolts (torque-to-yield). Torque the LS7 rocker arm bolts to 22 ft lbs (30 Nm) plus 70 degrees. Verify against your service manual. Confirm each rocker rocks freely on its trunnion with no bind.

Fit new valve cover gaskets. Torque the valve cover bolts to 106 in lbs (12 Nm) in a crossing pattern. Verify against your service manual. Reinstall coil packs, plug wires, and new spark plugs. Torque the LS7 spark plugs to 15 ft lbs (20 Nm). Verify against your service manual. Reinstall the intake manifold with new gaskets if any port surface was disturbed. Torque the intake manifold bolts to 89 in lbs (10 Nm) in the sequence specified by the service manual. Verify against your service manual.

Reconnect the battery. Crank with the coils unplugged until oil pressure registers. Reconnect coils and start. Let the engine idle for fifteen minutes while listening for any ticking or knocking that would indicate a keeper that walked out or a rocker not fully seated. Perform a hot leakdown on all eight cylinders and compare to the pre-service baseline; every cylinder should read equal or better.