Anyone use an angle gauge when torquing the head?
 

The second and third steps are 90 degree turns. A gauge would be more accurate but I haven't read anyone mentioning it's use...

source

YES you should use an angle gauge for angle torquing.

In the W123 300D / 240D FSM it says that you may estimate the 90 degree torquing angle. See chapter 05-115 page 12.

"Estimate the torquing angle... [apply] wrench handle and ratchet parallel to centre line of engine, and turn until it is at right-angles to engine. Do not use a torque limiting wrench for applying the torque angle"

I do not know if that is appropriate for your engine though (partly because you didn't state which of your cars you are talking about!)

I didn't on my 2.6. I torqued them down then did the 90 by eye. No leaks solid compression.

I eyeballed it. 90 degrees its pretty obvious.

Eyeballing it is the easy part. the problem is your brain telling you that it swears the bolt is going to break while you are doing the second 90 deg:D.

Yeah, I find myself pulling on the wrench for all I'm worth while turning my head and squinting to avoid flying pieces of head bolt when it shears off into a million pieces. Feels like 200 lb-ft at least, but probaly not.

No angle gauge here, easy to hit 90 degrees pretty accurately with the inline six head.
But with that kind of bolt torque, it's important to follow the cleanliness and lubrication recommendations to achieve proper clamp load and even pressure.

DG

Use the gauge. You can get a cheap one at AutoBone for like $19. Yes the 90 deg is easy to eyeball, but there are times when you may have to pick up the wrench and move it to complete the 90 deg rotation due to the hex being in the wrong location or some interference in the engine bay hitting the wrench handle, e.g. the firewall. It's poor economy to save $19 for a potentially $$$$ screwup. In Oklahoma we used to call that kind of thing "a dollar tripping over a dime", trying to save a nickel on a potentaily expensive screwup.

If you screw up turning a wrench 90 degrees, you shouldn't be working on an engine.