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MG Midget and Sprite Technical - Torque Paranoia

This illness has definitely got me by the throat. I've been fitting the oil filter head and pipe this morning, and the only value I found in Haynes was adaptor to head = 19-21 lbs/ft. That was nerve-racking enough, because with PTFE tape you get a click from the wrench, then if you go at it again you get another half a flat, then ditto, ditto, ditto. It stopped eventually.

But, what about the filter head to block, with its tiny gasket, and what about the banjo?

BTW Dave, I attach this to show how pretty your filter head looks.



Nick and Cherry Scoop

Very pretty it looks, too.


Metro manual quotes 16 lbs/ft for nuts (and studs). That is for a UNF thread. Your set screws will be UNC, no doubt.
Dave O'Neill 2

Are you using teflon tape on retaining blots? It should be used only joints where some liquid flows through. Any place else and you get what you got. The tape makes the threads "slipperyer" giving you a false reading. On the sealing joints you tighten until it stops like you would without the tape.
Martin

Oh no, Martin - only on the tapered adaptor into the filter head.

Thanks, Dave. Is it more, less, or the same , with UNC threads? Less, according to Greybeard's torque table.

The 1/2" AF UNC screws for the fuel pump to block are quoted at 14 lbs/ft in Haynes, and the two for the filter are 9/16" AF UNC, so ???

And what about the Banjo, which is something like 15/16"?

Sorry about this. I must have had a lot more confidence 12 years ago when I built my only other A-Series.
Nick and Cherry Scoop

Take a tea break, your to close to this project

this is going to be fine, just snug it up tight, not like over tight just so it feels soild

When you fire it up, if it leaks rhen you know you need another good lick with the wrench.... there is nothing stress related or requiries a precision torque

The main thing id lose sleep over... are those 2 bolts contacting the crankshaft in anyway, if you can spin rhe engine by hand and not have any flouling and you got around 18 to 25 ft pounds, your golden

Take a bow your the man, the engine looks great well done

Remember these engines came from the factory with a lot of slop built into them, and they wear it very well, this engine is not a $40xxx L1 corrvette engine that requires meticulous massaging.

We are with you, some of us have been there were your sitting, you just have to belive in your self and go for it, you will be glad you did.

Your the man of the hour, the legand of the internet, you got this, you alwaays have
1 Paper

It is a bit paranoid to make over-use of a torque wrench isn't it? I would only use on safety-critical nuts (hub nuts for example), on very tight nuts which are at torques which are outside my ability to manually judge (engine pulley nut) or on performance critical (head nuts).
For the rest I hope I have developed a "that feels right" sensitivity based on stripping threads by overtightening in the past!
Graeme Williams

Yes, Graeme, it is! Hence the thread title. Too much time to do the job is probably the reason, and while Prop's comments are very kind, that's also the reason it looks OK. Though I might yet get a pot of BMC engine green paint.

Last time around I was still working, and used to dash out to the shed after tea for a couple of hours, and I don't remember worrying about the fastenings if I had the correct spanner, unless they were in the list in Haynes. Good to follow all of those, I think, because some surprise you by their low torque - sump screws, for example.


Too much time for typing, too.
Nick and Cherry Scoop

Generally, on non critical fastenings, using the right open ended or ring spanner will give the right amount of torque if pulled up snugly without straining!

It also depends on whether there is a gasket in the joint and what type of gasket it is.

No gasket or thin gaskets just snug up tight - if a spring washer is under the bolt nut then snug till the washer is flat.

Thick gaskets, rubber, card or cork, then use Hylomar sealant and snug up gently, especially on tin items like front cover, sump and the side covers that use thick gaskets plus a rubber seal under the bolt head.

If the nut is on a stud and a thick gasket is used - e.g. thermostat housing - then use a nyloc nut which will stay put even though it is only lightly torqued.
Chris at Octarine Services

THe basic rule is if it shears off it was too tight. Try a bit less next time. If it falls off it was too loose. Try a bit more next time.
Graeme Williams

I agree Graeme what 'feels right' using the correct sized spanner seems to do the trick. If I recall there were relatively few torque settings specified by the factory back in the day probably because it was chunks of old cast iron! I guess we have got used to using setting for most screws and bolts these days as the materials are more fragile and the tolerances closer.
Bob Beaumont

Still it's something to torque about!

Coat?
Graeme Williams

One little point here is that if you are going to look up the torque of these bolts on a universal chart- I notice the sizes being quoted on here are 1/2" and 9/16"--these are the head size of the bolt whereas the torque spec. will be quoted on the actual shank size of the fastener
Don't get the pair mixed up-----
willy
William Revit

Whilst I agree about using the right spanner there is a difference between using open enders and rings. I always remember my uncle, who was in the Fleet Air Arm, saying that they had ring spanners to undo things but you were only allowed open enders to tighten them up. You were in trouble if caught using a ring to tighten a bolt.

Trev
T Mason

Trev: my "standard" ring-spanners are longer than the equivalent open-enders so I can see that could screw up the "feel". However, like a lot of people, I favour combination spanners. Would be interested to know any ideas as to why the open end should be the choice for tightening.
Graeme Williams

This is wonderfully reassuring. Thank you. I will try to be calm and sensible.
Nick and Cherry Scoop

It's all about "feel" but no-one can really know if it's just right - more of an instinct I suppose. But it could be that my "feel" results in a lesser or greater tightness than someone else. But probably not enough to matter on old stuff.
Bill
W Bretherton

It's worthwhile grabbing hold of the correct spanner and say a 1/2" af bolt and seeing just how much welly it can take. Remember that and use just a bit less next time.
Graeme Williams

The material that it is going into also has a bearing on how tight you can do it.
Dave O'Neill 2

If you put a full nut on it takes a fair bit of effort
Graeme Williams

Graeme--I went to look up some info on nuts and found this --They can be a problem---lol
willy
https://www.youtube.com/watch?v=1XsUjY5Z8fk
William Revit

I confess I only use a torque wrench on critical bolts like bearing caps and cylinder head nuts, and some suspension bolts. Everything else I just tighten by feel and 50 years experience.
Mike Howlett

Same here mike

But i always get brain frezze on spark plugs...

Iguess 280 ft lbs never seems like enough ...haha

Prop
1 Paper

Engine fasteners I always tension apart from non critical/non stress items like covers, oil pans,fuel pumps etc
Wheel nuts-every time out of habit
willy
William Revit

This thread was discussed between 09/08/2017 and 12/08/2017

MG Midget and Sprite Technical index

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