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MG Midget and Sprite Technical - 1275 cyl head torque specs?

Just had valve job done on 1275 cyl head and was looking for suggestions on what to torque at? Thanks.
GF Greg Smith

for a 1098 and a 1275 cc plain studs are 42 Ibf ft or 5.8 kgf m, studs stamped'22' or with drill point are 50 Ibf ft or 6.9 kgf m according to my haynes maual.
G Scott

GF

Are they stock studs or are they ARP hardware, you cant torque Arp to the same standard as stock

If they are ARP.. then 60 ftlbs with 30 wt motor oil (yeah that sounds high to me also) or with the special lube from ARP the torque is 40 ftlbs

if you have an aluminum head with ARP then 50 ftlbs with 30 wt motor oil or 35 ftlbs with the special ARP lube


If your not sure what studs you have (arp)... take a stud to a good high end machine shop that does blocks and heads esp race stuff. they will know. arp is the gold standard

remember to devide the torque into 3 ... dont torque all at once .

if the hardware is old..., at least buy new nuts and washers... not from regular stock... needs to be 5 grade minume but do 8 grade if possiable

prop
Prop

you crazy people with your strange lbs

Haynes says 68N/M with a small drop of oil.
i usualy do 65N/M as skimmed heads require less torque.
Onno Könemann

yeah but who the heck uses a "newton", granted I love the fruity taste of the fig inside.

Just my opinion but fig newtons make a better cookie than a unit of measurement. LOl

Prop
Prop

You have to admit after eating the 68 newtons you just measured with, its going to put the "lbs" on big time

Prop

Prop

"I usually do 65N/M as skimmed heads require less torque."

Why is that Onno, given that the requisite torque sets up a given amount of STRETCH in the fasteners, and it is this stretch that locks the male and female threads together, thus providing the clamping load?

Or are you saying that skimmed heads require less clamping load? I would have thought (if you WERE going to alter the torque settings) that the reverse is true, given that skimming a head will produce a greater Static CR!
Deborah Evans

because Keith Calver states:

OK. Basic brief on head gaskets over – head studs and torque settings. Now, I've heard all SORTS of weird stuff about how folk torque their head studs down. VERY weird. I don’t understand any of this as it’s plainly laid out in black and white print in a million manuals. All you have to do is torque the standard head studs down to 42-45lb ft (a generous lee-way there I feel), DRY. That’s no lubrication on nuts, washers, or studs. ALL torque settings in the manuals are quoted with the relevant threads DRY. And that's the way they're done at the factory.

And:

1 – DO NOT use any sort of thread lock compound. Yes, some folk did. No, I couldn’t believe it either. I have to say it’s a new one on me. Big-end bolts/nuts? Yep. Heard that one. Mains bolts/studs/nuts? Yep. Heard that one too. But head studs/nuts? Nope. Never. The excuses (sorry, reasons) were many – but the ‘well I couldn’t afford new ones, and I thought the old ones might have worn threads’ was the most common. Unless you use the specific thread-locking compound that is made just for the application you are using it for - it will detract markedly from the actual torque setting - some by as much as 30%. This is because the compound starts to 'set' with the friction generated when doing a nut/bolt up. Plus it can get under the head of the nut/bolt, set when torquing up, but will 'powder' from vibration/pressure when the engine is used. A small gap is then caused, and the torque setting/clamping pressure is relaxed/reduced. Not good.

2 – If standard spec studs/nuts are used, do them up with NO lubrication to 45lb ft. If you must oil the threads, do them up to 42lb ft, or if using a moly-based oil, 40lb ft.

3 – If using either Mini Spares up-graded stud/nut set OR ARP ones, use a lubricant – and preferably a moly-based one – and torque ‘em up to 45lb ft.

Why? The main reason (there are several) is because over-torquing will almost certainly distort the gasket to the point where failure is likely to occur. The most likely areas are the fire-rings that seal the head face (chambers) to block face (bores) off. Particularly between the bores where the steel fillet inserts are in non-copper/composite gaskets, and where modified heads have been a little over-zealously ‘relieved’ around the gasket fire-ring line. Especially between the centre two exhaust valves.

-so my haynes (mini) manual is way over according to CK
-i have broken 3 headstuds going to 68
-have read other sources that state skimed heads deforme earlyer and over torque


The problem with these things is that the experts give conflicting information.
As an amateur i can then only make my own conclusion using the (conflicting) info and my experiance.

Onno Könemann

I hear ya onno,

No doulbt you were reading with great intrest into what I was finding about 2 weeks ago about gasket walking... its amazing the trash you have to learn then figure out when something stupid like this happens. you just want to scratch your head and say why!

anyway take a newton measurement and then eat the fruity filling 1st...I dont think your out of spec by much. Ive heard that to about less torque on a skimmed head... I just figured the head has less metal so might be easier to crack


Prop
Prop

After 3 attempts, I have finally gotten my head gasket to seal more or less properly. CR is 160, all 4 cylinders and the oil leaking between the head and the block has been reduced to a minimum (there is no longer sufficient leaking to make it to the exhaust manifold).

It is my impression that the ARP hardware complicates the torquing and sealing as I never had problems with original hardware. The recent episodes, especially with the oil leaking onto the exhaust manifold, have been tedious.
Glenn Mallory

This thread was discussed between 08/06/2010 and 13/06/2010

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