Head torque settings

[moggymaniac]

Hi all,
Have finally got the 5 speed working...but blew the head gasket very quickly after torquing my new head down to 40 ftlbs on the 1275, as with the 1098 engines...rookie mistake...!
I've now torqued down the the midget 1275 torque settings of 42ftlbs and 50lbs if drill marked or marked "22". So we should be good now....
However....the head is a 12940 big valve mini head recon by mini sport at stage 2 with standard size combustion chambers, so compression remains standard, I was told. I'm using a payen bk450 non copper gasket as recommended on a mini forum. The engine is midget 1275. Have I torqued it correctly considering the above?
Just don't want to have the head off again if I can avoid it.
Thanks in advance!
Jamie

[philthehill]

It appears from reading your post that you have set the head nut torque to two different settings.
All head nuts should be set to either 42lb ft or 50lb ft. You should not have two different torques on the 9 head studs/nuts as you will be asking for trouble.
Head studs and nuts should be used in sets, later 1275cc higher tensile head studs are also marked by a pointy top and a 'Y' stamped on the top and those including the dimpled top are what you should be using (as I do not have any high tensile studs marked 22 I cannot comment on them).
The high tensile studs should be used only with the High tensile flanged nuts.
The 1275cc engine should be be fitted with the high tensile studs and flanged nuts and therefore you should have already the high tensile studs and flanged nuts fitted.
Not all high tensile studs have the same markings but they all have the same torque setting.
As regards the torques setting for the head nuts it is safe to set the original non flanged nuts to 42lb ft but ideally you should have all high tensile studs and flanged nuts and set the torque to 50lb ft.
As regards the head gasket the best gasket to use is the copper gasket re-torqued after the first heat cycle.
http://www.minispares.com/product/Class ... assic/head gasket.aspx|Back to search

[moggymaniac]

Ok...
So as in the picture attached my studs are a mix of drill point (2,3, 5,6,8,9) front to back) and either dome top as with the 1098 engine I believe (1+7) or flat top but unmarked (4). All nuts appear inflanged, the same type as was on my 1098 engine. I bought this engine as a low mile recon and the head was the aeg163 casting only utilised 9 of the 11 studs due to the block casting, which i sold on. Should I have all marked (high tensile) studs with all flanged nuts then? Now you can see why I thought to use two different torque settings...as the studs are different!
Cheers

[philthehill]

Thank you for the photo.
You appear to have a mixture of marked high tensile studs.
The only studs I have concerns about are the one hidden under the throttle cable (which looks to have a dimple) and what appears to be a plain top low tensile stud on the manifold side (2nd one in).
High tensile studs with a pointy end can vary in pointiness from a slight taper to a large taper. The studs you describe as domed are in all probability high tensile tapered.
All high tensile studs should be fitted with the flanged nuts.
To save stripping the head and as you have not run the engine - I would suggest that you obtain a set of flanged nuts and replace the nuts one at a time and torque each replacement nut to 50lb ft before moving to the next nut.
Regarding the plain top low tensile stud I would replace if possible with a high tensile version.
Replace the nuts in the same order as torqueing down the head.
Do not slacken off more than one nut at a time.
Re-torque after the first heat cycle.
Drain the coolant from the block before undoing any nuts.

As an aside a 10 stud and 1 bolt head can be fitted to a 9 stud block and a 9 stud 940 head can be drilled to accommodate the additional stud and bolt. Most people myself included fit a high tensile 3/8" stud to the front of the head instead of the bolt but still torque the bolt to 25lb ft.....Paint the nut red to remind yourself that the torque setting is only 25lb ft.

[moggymaniac]

Unfortunately I have since run the engine very briefly since blowing the last gasket and fitting a new one with two different torque settings. I'll get some flanged nuts which I've head don't require a washer between them and the head?
I'm not sure where to buy a High tensile long stud...I see some websites that sell single ARP studs, but I've also read that they're to be inserted into the block using engine oil as a lubricant or sealant if it is a stud that protrudes into a water-way.
As I've run the engine, I'm guessing it's a head off job again!

[philthehill]

The long high tensile stud is available as a singleton item from MOSS see link below:-

http://www.moss-europe.co.uk/stud-cylin ... soc=417291

Since you have only run the engine very briefly I would give replacing the nuts and stud as I have described above a try before removing the head which should only be done as a last resort.

When fitting the flanged nuts they do not require to have the flat washer underneath them. Screw the stud into the block finger tight and fit and torque the flanged nuts dry.

I have sent you a PM.