Pop rivets were first installed on the timing cover on 1980 models to help prevent anyone (except the dealer) from tampering with the timing system.
They were to be removed by the dealer for servicing the ignition and then replaced with new ones.

Removal of the rivets are fairly simple. Just drill out the center of each one (which is the strength of the rivet). The size drill bit used is not critical. It should be wider than the center hole of the rivet but not as wide as the rivet head O.D.
The head may start spinning while you are drilling it.
If that happens, just hold one end down with a screwdriver and continue drilling.
Try not to drill too deep.
Once the center has been drilled, sometimes the head will just fall off.
If it doesn't, you can use a small screwdriver to pop it off.

Drill the center of the rivets. 1)	Chisel off the head if it didn't fall off. 2)

Then lift the cover out. 3)	This second plate is in the back. 4)