Torque values for 750 Atlas (1967) engine?

Previously wrote:

All-

I am looking for the torque values for my 167 750 Atlas. The engine has recently been rebuilt, and I was advised as part of the run-in to re-torque head bolts, etc. Unfortunately I do not know what the values are for the major componenets that will nee to be checked/re-torqued. Any help would be appreciated.

Hello its because the running of the motor will put stress on the bolts . so after a good run you need to re-check the torque settings and do not forget the nuts on the barrel base , Yours Anna J

The Norton Maintenance Manual and Instruction Book (the Green Bible) does not publish torque figures. I have always used the calibrated arm with an appropriate length ring spanner or socket handle - that is to say not too long. It has worked for me successfully since 1969. However, a quick web search should find torque figures for various bolt diameters. If you are using a torque wrench, you must use the appropriate figure for dry or lubricated threads. It's eary to over-torque a lubricated thread. As for tightening down the head, I generally do it after 50 to 100 miles and check the valve clearances at the same time. If there is any noticable re-tightening, I will then do another check at 500 miles. Don't use stainless head bolts.

Haynes gives: 20 ft.lb for the 5/16th and 30 ft.lb for the 3/8th. However, you won't get a socket and torque wrench onto all of them and I follow Gordon's method. Not everyone has a feel for tightening nuts and bolts though.

PS Those are for the head!

Hi William,

I found years ago on the Old Britts' website a whole range of torque values for Nortons. It is still there:http://www.oldbritts.com/n_torq.html. They worked ok for my 650 Dommie. As for the tightening sequence, the tech section of this very website lists 2 possible sequences, see here:http://www.nortonownersclub.org/support/technical-support-heavytwinsand see tightening sequences in the cylinder head and barrel section.

You will need either a slim 'crows foot' for your torque wrench to reach the nuts that are fitted from the bottom, or (as I do) a known length spanner and a spring balance. eg, for 30lb.ft, pull a 6" spanner with a force of 60lb (30lb/0.5ft), a 9" spanner with a force of 40lb (30lb/0.75ft). and so on. Just make sure that you pull at a right angle on the spanner. Your spanner will need to be slim to go through the cylinder fins.

Yours being an Atlas it will have some (all?) smaller dia head bolts than either the 650 or Commando, so check what size they are before retorquing. I don't know whether it is just some or all are smaller, but someone on here will.

Hope that this helps,

George.

The Paul Dunstal, Norton Tuning book on page 31, gives all the data that you have asked for concerning the Atlas engines. It is shown in inch lbs, but it has the conversion to foot lbs shown or divide by 12.