I'm putting certain parts on my engine back together but some of them such as the valve cover require torques as low as 4 lbs. How do I measure that as there aren't any torque wrenches I can find that go that low?
If you're doing a valve cover and you have no torque wrench, tighten the nut to where it just has slight friction, then turn your ratchet about 45deg. That torque is not critical, it just keeps oil from passing the gasket.
On valve cover bolts, I use a 1/4" ratchet and use my thumb to steady the ratchet and pinky to turn it. When pinky starts to hurt, your pretty good I use the same technique with water pump bolts on aluminum crank case covers since anything over 10 ft/pounds causes them to strip out