Head bolt torque settings

[Nickfrank]

would someone have this for the 650 twin? There is no mention of it in the owner's manual. Thanks.

[paul.jameson]

Such things are not generally quoted in Ariel literature, presumably because nobody had or used a torque wrench. The important thing, with copper asbestos or composition gaskets is to tighten the head down, then run the engine a little, let it cool down, then retighten (not forgetting to re- adjust the valve clearances), the do a few miles, retighten (not forgetting to re- adjust the valve clearances), do a few more, retighten (not forgetting to re- adjust the valve clearances) and so on until the gasket doesn't give any more.

There is an Ariel drawing dated 1956 which suggests 300ins/lbs for cylinder head nuts for OHV twins (on the 500cc KH, only one of the 9 studs can take a socket). As it suggests the same for the Square Four (which would simply pull the studs out of the alloy and you can't get a socket onto some of the nuts so you can't use a torque wrench on all of them anyway) I would strongly advise treating this figure with a large pinch of salt. Follow the procedure in the paragraph above and you won't go far wrong.

[Simon.Gardiner]

There was a time when the copper gasket was infinitely less prone to blowing than copper-asbestos. Also I'd always replace the head-bolts with allen screws 'cos they're good and strong and easier to get really well tightened down.
Head-bolt torque would be the same as an iron-head A10, if that helps any.

[andy.mcgregor]

SRM recommend 32lbft for the head bolts on the BSA A10:
http://www.srmclassicbikes.com/technica ... e-settings

[Nickfrank]

Paul, Andy, Simon, thanks for the advice! Nick.

[satchison]

Would these torque values also apply to a 1947 NH 350?

[paul.jameson]

No. Simply do the head bolts up tight, and use a smear of red hermetite on top of the spigot. Tight as in tight, not ***king tight and certainly not really ***king tight.

[Nickfrank]

Well, I broke a head bolt when retorquing the head (aaarrrggg!) as for whatever reason, my torque wrench didn't give me the necessary click as it did with the other 8 bolts. I have ordered all new bolts from Draganfly. A few questions. The head gasket is copper and appears unmarked. Can I reuse it or should I put in a new one? The only ones DF carries are fibre vs copper.
When replacing the pushrods, how do you know which lifters the inlets and exhausts goes in when looking down the hole? They all appear to be in a horizontal line. When replacing the rocker box, is there a technique for getting the pushrods into the rocker arm cups? Looks like it might be a bit of a sod. Many thanks.

[nevhunter]

The iron KH/KG's had a name for being difficult to manipulate the pushrods into.
Relating to other BSAs etc
If you rotate the engine in a forwards direction as the exhaust closes the inlet starts to open. This will identify the particular valves for you. The engines are mirror imaged about the centre line.( Crankcase split.) Nev

[john.whiting]

There is a special tool for positioning the pushrods.When I was a lad,I always used a kitchen knife with a thin blade.In the "Motor Cycle",there was a segment where readers were awarded a pound for good ideas.A reader would suggest this tool,get their pound ,then there would be a storm of protest that this was a BSA service tool.Must have happened ten times over the years.Regards John.