The right torque wrench

A box spanner, etc, with a T bar and one hand across the top of it. Tighten as hard as you can - it won't be far out.

However, someone is selling Sykes Pickavant spark plug torque wrenches (18 ft.lb only) on Ebay with a low starting price.

IMHO, reasonable price torque wrenches don't exist.

You get what you pay for. £22 full price for a torque wrench must be nearly 'pound shop' quality.

Teng tools, £38:

They have a number of others at slightly higher prices, but with a bigger range of torque, so probably more useful. This one at £44:

Take it to a calibration Co., only around £15-25.

Alan.

Yep - You are not going to strip the thread of a spark plug so its not that critical

Ain't that true.

You can use another torque wrench coupled and see if they trigger at the same time. using two sockets and allen key between or allen key socket and a socket.

I have three to span a reasonable range - 1/4", 3/8" and 1/2" square drives with the largest one suitable for use with my tractor/FoB 4x4.

This is similar to one of the ones that I have that I consider "OK":

You don't need a torque wrench. Just tighten them firmly - not as firm as if you were bolting a battleship together in a shipyard, but firm enough not to slacken off.

No problem.

McK.