torque settings

[Bob Culver]

There is a bit of a case for tight front hub nuts in that it pre stresses the sharp radii. However the stubs do not fail there. (Other cars with taper rollers tre adjusted just finger tight) High torque just collapses the spacer piece. 
Tab washers are dubious; the material has to be just right.
Split pins are a pain and the temptaion is to tighten to align. Very many Seven b.e bolts are stretched. Yet for non racers the bolts are very generously sized.  If the caps seat properly it is debatable if any lock methd is required. (My Seven and Jowett ran without) Many other makes with 5/16 big ends much more stressed accept less than 20 ibs ft.
According to Machinerys Handbook the accuracy of torque wrench cf actual tension is +/- 25%, so if using high figures easy to snap.

[Chris KC]

Ah now the accuracy of torque wrenches, that's another thing altogether. +/- 25% is probably being rather kind.

[Ian Williams]

Before we get all excited and dramatic about Torque wrench accuracy consider this, take a sample of all the bolts tightened by a myriad of owners without torque wrenches and see what range you get...... a dam sight more the the range of those using torque wrenches I wager. Maybe someone who regularly fits heads and who has a good feel can achieve consistent results, but I doubt many can. Another point besides the actual pressure applied is the consistency of tightness across the head, this is where a torque wrench scores. Chris has made note of lubrication, it is also worth repeating that Nuts/Bolts should run up freely along threads with your fingers, if you need to use a spanner the thread is dirty or damaged and you will not achieve consistent torque results.

[Tony Press]

" Fronts I don't know, I probably do 50, and the split pins. "

The front hub stub axle nut only stops the hub from coming off so doesn't need heavy tightening - as long as the nut is a little more than finger tight and the split pin fitted it will be good. 
Being two ball bearings there will always be some hub movement and overtightening does nothing.

[Colin Reed]

HI All,
Totally agree with Ian,
One thing that does help is to use a inch Lb torque wrench as most of the nuts & bolts on the engine are relatively low torque ,
also the increments are finer allowing closer tolerance 

just a thought 

Colin
NZ

["Slack Alice" Simon]

Having bought a good quality torque wrench I was surprised how big a variation there was in my spanner- tightened head nuts. 

At least now they are all the same - ish,  and not leaking from a re-used gasket.

[Tony Press]

Within +/- 25% of each other ?

[Bob Culver]

Hi Tony

I gather the variation referred to the typical range of bolt tensions for the same applied torque. Turn of nut method +- 15%, load indicating washer +- 10%; bolt elongation 3-5% (25th edition p1404)
Engines dismantled often reveal old replacement gudgeon bolts with letter R indicating standard h.t hardware (S is/was superior)

Working on moderns can be misleading. The bolts produced under very controlled conditons are tightend to remarkable torques.

For 45 tsi steel typical recommendation for BSF 1/4 7.5 ilbs.ft, 5/16 15 lbs.ft

It has been covered before but torque wrenches can be calibrated with weights. In the 1960s when expensive my father and self made wrenches from a piece of old axle and a length of 1/2 inch ht steel. See them now at swapmeets for $5!

[Jamie]

Posted by Bob Culver - 8 minutes ago Hi Tony

"It has been covered before but torque wrenches can be calibrated with weights."

I did this with mine very recently, using bottles of water hanging on string 1' from the centre of the square drive. I was pleasantly surprised at the accuracy of my two torque wrenches. Both are from the early 80s. One was a Williams device which cracked at 18lbs ft on the scale with 15lbs hanging on it. The scale is quite coarse, making accurate readings quite hard. The other, a bendy-bar type, was spot on, much to my great surprise.

It was reassuring, even if one is a little out.

Jamie.

[Bob Culver]

While on the topic, where torque wrenches are esp useful is when working in awkward positions. Accessible head studs can be judged reasonably with an appropriate length spanner but main bearing caps and the like on conventional cars are awkward lying underneath a car and each requiring a different contortion.