I've just removed the valve cover for the first time to inspect the cam.

The sockets in the cylinder head bolts are full of sludge but the rest of the inside of the head and cover seems fairly clean. I haven't looked inside any other Zcar engines so I don't know if this is normal. Any wisdom from someone who’s got more experience would be appreciated. I’m now afraid of what’s in the oil pan.

Vince

77 280Z

From what I've learned sludge was caused by cheap oils. Especially years ago when the cheap oils didn't have many detergents. It can accumulate anywhere that oil has been. My advice is unless your planning a rebuild soon, leave the engine alone. Change the oil regularly, but don't take anything apart, ie.. oil pan, head, timing cover etc.. If you accidently dislodge a speck of sludge it can clog an oil passage or bind up your oil pump. Thus resulting in catasrophic engine failure.