Bob, the head marking should have two numbers, either 4.6 or 4.8. Standard torque tables indicate 3-4 lb.ft., or 36-40 lb.in. The application is "cap screws" being screwed into aluminum threads, so you don't want to crank them down. This is much less than the standard torque for 8.5 cap screws into steel threads (6-7 lb.ft.)
I don't know of a mechanic who actually uses a torque wrench on valve covers. The tool to use is a 1/4 inch ratchet and a 10mm socket. Spin the bolts down until they start to compress the gasket, then tweak "tight," going from side to side. A paper gasket will make up pretty quickly; a cork or composition gasket will do so more slowly; in either case, what is critical is that the gasket have some compression, but not too much at the screw points.
If the seal is an O-ring in a groove, generally the objective is to tighten so that there is contact between the two pieces (valve cover and cyl. head). That will make up very quickly.
Pro mechanics do jobs like this by feel, and "snug" with a quarter inch ratchet will get you there. If you want to calibrate your hand, screw an M6 bolt and split lockwasher over a nut clamped in a vise, and use your torque wrench. Then "feel" that torque with the tool you will use.
Hank
