Torque wrench

Two torque wrenches are mandatory. One is not enough as martin mentioned.

Clicker type torque wrenches are really handy but less reliable than a bending beam type torque wrench. The bending beam type will never go out of calibration and never break. If the pointing indicator gets bent on the bottom of your tool box simply bend it back so it points at zero when unloaded. Couldn't be simpler. Click type torque wrenches are more convenient but after the spring inside gets weak the torque calibration will be off.

I've got a couple of dial type torque wrenches (made by Precision Instruments) which are a variation on the bending beam methodology, only much easier to read. Mine as labeled Snap On but they are identical to the standard type dial units Precision sells. These units are nice because they also don't go out of calibration. Problem is they don't like shock loads. I was torquing the head on a friends bike and the head nuts where momentarily slipping and sticking and this movement broke a small screw inside the mechanism. It cost me $50 + shipping to fix. Cheaper than purchasing a new device though. The old standard beam type is what I use now unless I know the fasteners are smooth and won't jar the mechanism.

I didn't have an in-lbs wrench so I figured I'd do it by hand and guess. I tightened my cam chain tensioner just a tiny bit, because 40 in-lbs has to be just barely snug right? Turns out I was WAAAAAAAY off and 40 in-lbs requires a lot more force than I guessed. Alas, I am not an experienced technician

Autozone has in-lbs torque wrench on their loaner program. Pay a $50 deposit and get $50 back when you return it. Otherwise check harbor freight and make sure to get a free item with your purchase!

I found out I was for years a good 20 inch lbs light on cam cap bolts (50 before - 70 now), valve cover bolts too and a good 20-25% less on the oil drain plug, filter cover and plugs..... but I still use about that much less on these 3 items as they sure feel to me as they could be damaged with much more.