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+--- Thread: head bolt torque and block (/showthread.php?tid=7900)
head bolt torque and block - keith smith - 11-08-2022
hi can anyone tell me the torque settings on the 750cc head,, and the block settings too please,,, guys and dolls ,,keithy
RE: head bolt torque and block - David Stepney - 11-08-2022
18 to 20 ft/lbs for the head appears to be the recommended figure (although I tend to a risque 25!) I have not seen a torque figure for the block to crankcase nuts, as they can only be tackled with a ring spanner. As my first boss would have said: "
Do them up until they are perfectly tight." (He never did explain what 'perfectly tight' meant.)
RE: head bolt torque and block - Howard Wright - 11-08-2022
Hi Keith
This has been covered many times in the forum. David’s advice is spot on although on my torque wrench 26Nm (19 ftlb) is easier to set.
Cheers
Howard
RE: head bolt torque and block - Humps - 11-08-2022
For the block to crankcase nuts, the studs are in aluminium and I think a certain amount of sensitivity is require to avoid stripping the threads in the crankcase?
RE: head bolt torque and block - Denis Sweeney - 11-08-2022
A7 Companion includes an article noted as being taken from the Austin Service Journal January 1939 and states for 5/16” studs a torque of 360 in lbs
RE: head bolt torque and block - stuartu - 11-08-2022
Who am I to question the wisdom of the Companion? Still...
My latest s/c Ulster engine with 8 stud block was inclined to exhibit a little blowing up the studs at 4000+ rpm with a solid copper gasket and the cast iron 14 stud head torqued to 22 ft lbs.
I thought a little more torque might not come amiss but had no desire to cause myself more problems. I happened to have a 1937 block which had suffered the attentions of a tech college motor engineering department but had good threads in the top of the block. I decided to use this as a test piece with current Seven Workshop studs, Seven Workshop machined nuts and a cast iron cylinder head. At 24 ft lbs all was well. At 26 ft lbs stud and nut survived but the land around the top of the thread in the block began to rise.
I would think 360 lb in (30 ft lbs) ) is distinctly dodgy although I do know of one case where it has been used satisfactorily.
I wouldn't!
Regards,
Stuart
RE: head bolt torque and block - John Mason - 11-08-2022
Re your input on this thread David. My old mechanic friend used to say when I asked him how tight I should do nuts up. Tight is tight he would say.
John Mason.
RE: head bolt torque and block - Ruairidh Dunford - 11-08-2022
The Companion has several instances that cause the “it is written down, so must be true” brigade, to orgasm.
RE: head bolt torque and block - David Stepney - 11-08-2022
My first boss, who incidentally, was a superb motor engineer, only had three torque settings:-
1. Murder tight - this usually involved scaffolding poles
2. Perfectly tight
3. Conveniently tight - do the nut down and then give it a a sharp nip with the spanner.
Young Leon has just watched me put up this post and has remarked that I say exactly the same things to him when we are working on the cars.
RE: head bolt torque and block - Charles P - 11-08-2022
(11-08-2022, 10:34 PM)Ruairidh Dunford Wrote: The Companion has several instances that cause the “it is written down, so must be true” brigade, to orgasm.
What a turn of phrase.
Good job I've eaten.
C