Torquing the head

Dave ..........I think that you are going to find a lot of engineers will not agree with the accuracy of this method of torquing.

I agree with Phil. Maybe someone with a degree in physics will comment on the angles and torque applications involved.

A simpler method would be a 12" long ring spanner (30cm to you afflicted with the metric system) and a fishing weight scale. The scale should pull at 90 degrees to the spanner. I have also seen the new digital type scales being sold for weighing your luggage.

Hi David, as others have hinted at Torque = force x Effective radius at 90 degrees to the point of rotation. I suppose if this drawn out to scale you will be able to find if the effectine radius is the same. Too short and the nuts are loose, too tight and the stud of nut COULD fail.

Cheers Roger

Previously david_evans wrote:

Torquing the upward facing head fasteners is no problem but the two sleeve nuts and the rear central nut can cause problems. By using a 1/4 whit combination spanner with a 1/2 inch square drive torque wrench at 90 degrees you can get the set torque on these three nuts.

I have just rebuilt a 650 Twin and had the underside cylinder head nut torquing problems that Dave had plus the crankshaft flywheel to bolt together.

My torque wrench solution was similar to Dave's. But first I put a 5/16" bolt in my vice and then wound on a nut with a thick washer to trap the head on the jaw tops. Next I torqued the nut down to 20fps. Then I replaced the 5/16" socket on the torque wrench with a 5/16" ring/open spanner. Because my torque wrench has a rachet I can position the spanner to sit nearly in line up with handle. Finally, I adjust down the torque preload on the wrench and then raise it again,torquing up the nut,until the clicker sounds just as the 5/16" bolt head starts to move. Then I know that it is about 20fps of torque moving the bolt and can safely use the wrench on the 5/16" cylinder head nuts and bolts.

Swopping the 5/16" spanner for a 5/16" angled head ring plus a reducer lets me set up the wrench for tackling the crankshaft after resetting the torque load. Similar moves to the above with a 3/8" bolt allows me to get to grips with the bigger 3/8"nuts.

Previously david_evans wrote:

Torquing the upward facing head fasteners is no problem but the two sleeve nuts and the rear central nut can cause problems. By using a 1/4 whit combination spanner with a 1/2 inch square drive torque wrench at 90 degrees you can get the set torque on these three nuts

Hi Dave,

This is a perfectly acceptable method as long as the spanner is at right angles to the toque wrench and you are very careful with how you push the wrench.

Consider (and I know this is not realistic but you will understand what I am getting at) if you pushed or pulled on the end of the wrench in line with the wrench rather than at right angles, you could tighten to failure without the torque wrench even noticing any torque.

Tony