These valve covers were originally used on 1987 Corvettes. They are cast magnesium.

Part Numbers
10055781 - 1987 Corvette Cover (Left Hand This magnesium rocker cover with central hold-down bolts is used on production aluminum Corvette heads. It has a Corvette emblem and no oil filler hole. Technical Note:  Rocker covers for Corvette aluminum heads require special hold-down bolts GM# 12338092, washers GM# 14094717, bolt gaskets GM# 14088793, and neoprene gasket GM# 14088564.  
10055782 - 1987 Corvette Cover (Right Hand Same as above, except right hand side with oil fill hole in place of Corvette emblem. Technical Notes:  See above. Use screw-in oil filler cap GM# 12558300.

Be patient when ordering these parts. It took me almost 3 months to get them. Hopefully yours won't take so long. The total cost of all the parts was about $200

There is a hole in the left side cover that needs to be plugged.

It is .915 in. I guess the original installation had a breather installed there. I used a 3/4 in. copper pipe cap. I had to grind the diameter of the hole slightly larger and sand down the diameter of the pipe plug slightly. I then painted the copper plug and tapped it in with a rubber mallet. Be careful not to push it in too far until you are ready to install it for real as there is no easy way to get it out again, as the underside of the hole is not accessable. I am sure that there are better things to use to plug the hole, I just used the first thing that seemed like it would work.

The installation on the drivers side is fairly straight forward. Disconnect the AIR pump fitting from the exhaust manifold and remove. This allows the valve cover to be removed. Install the neoprene gasket to the valve cover and replace on the head. I used the supplied Torx head bolts that came with the valve covers, although it appears that the original bolts might work also.

The passenger side requires that you remove the serpintine belt and remove the bolts rom the alternator so that you can rotate it out of the way in order to remove the valve cover. You may also have to disconnect the AIR pump fitting from the exhaust manifold to get clearance. The grommet for the breather from the original valve cover can be used in the new cover. It takes a little patience to get it to go in the hole. Install the new gasket on the cover and install the new cover. Reconnect the alternator, serpentine belt and AIR pump fitting.

These covers add a little something different to your engine compartment.

Michael Ellis S.A.I.L.
mellis@ddc.net