I am going to be torquing down my heads today hopefully. How much torque, if any, would I lose when using an extension? Also, if I need to use an extension with the angle finder, will the extension throw off the reading?

 

Assuming you are talking about a typical socket extension (90-degrees to the torque wrench) and you keep the wrench square to the socket, the reading won't be affected. One might argue that a long extension may slightly skew the reading BUT it's incredibly minimal that it isn't worth making a big stink over.

Now if you add a crow's foot extension that's a different story.

 

Just a regular extension.

 

Just use a 3" long 1/2" extension and no worries there - it is stiff enough not to make much of a difference.

 

There are 2 situations where an extension can affect torque.

1-You are using an impact wrench: Impacts apply torque in quick bursts and only turn the socket a few degrees with each burst. Extensions can create slack from flexing. The impact does not turn enough in one cycle to take up all the slack which kills the torque output.

2-You are using Torque to Yield bolts: While the initial torque reading will be correct, the angular reading afterward can be skewed by long extensions flexing if you put the gauge on the extensions.

If you are applying a smooth constant torque to the wrench, extensions will not cause the torque being applied to the bolt to be changed.