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Head Stud Torque Confusion

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Best Answer nicklouse , 15 April 2022 - 08:42 AM

Hi guys,

Going to put my head (12G1805) back on my A+ 1275 and bought some replacement studs (I believe they are C-AHT279A) from my local classic mini parts supplier. Whats confusing me is what torque spec I should use for the studs into the block. 

Mini Mania says 25lbft, Mini Spares says 48-52lbft, a similar product (CAM150) says 42lbft and a YouTube channel "Classic Mini Workshop" says Paul Hickey from "HRE IRL" says hand tight.

 

Who is right?

 

Mini Mania: https://www.minimani...ch_Settings_597

Mini Spares: http://www.minispare...gasket-problems

Classic Mini Workshop: https://youtu.be/nmr1sUVg7jg?t=439

 

Any information would be great as I would like to get the head done this Easter weekend.

 

Cheers
 

Sorry you need to go to Spec Savers or NZ equivalent.

 

Mini mania give no tightening torque for the studs.

Calver is referring to the torque of the  Nuts.

 

yes the studs are fitted hand tight.

 

I suggest getting a workshop manual.

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#1 Nootnoot11

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Posted 15 April 2022 - 07:11 AM

Hi guys,

Going to put my head (12G1805) back on my A+ 1275 and bought some replacement studs (I believe they are C-AHT279A) from my local classic mini parts supplier. Whats confusing me is what torque spec I should use for the studs into the block. 

Mini Mania says 25lbft, Mini Spares says 48-52lbft, a similar product (CAM150) says 42lbft and a YouTube channel "Classic Mini Workshop" says Paul Hickey from "HRE IRL" says hand tight.

 

Who is right?

 

Mini Mania: https://www.minimani...ch_Settings_597

Mini Spares: http://www.minispare...gasket-problems

Classic Mini Workshop: https://youtu.be/nmr1sUVg7jg?t=439

 

Any information would be great as I would like to get the head done this Easter weekend.

 

Cheers
 

 

 



#2 Ethel

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Posted 15 April 2022 - 08:34 AM

I vote hand tight, they'll get tensioned when you wind the nuts up on the other end.



#3 nicklouse

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Posted 15 April 2022 - 08:42 AM   Best Answer

Hi guys,

Going to put my head (12G1805) back on my A+ 1275 and bought some replacement studs (I believe they are C-AHT279A) from my local classic mini parts supplier. Whats confusing me is what torque spec I should use for the studs into the block. 

Mini Mania says 25lbft, Mini Spares says 48-52lbft, a similar product (CAM150) says 42lbft and a YouTube channel "Classic Mini Workshop" says Paul Hickey from "HRE IRL" says hand tight.

 

Who is right?

 

Mini Mania: https://www.minimani...ch_Settings_597

Mini Spares: http://www.minispare...gasket-problems

Classic Mini Workshop: https://youtu.be/nmr1sUVg7jg?t=439

 

Any information would be great as I would like to get the head done this Easter weekend.

 

Cheers
 

Sorry you need to go to Spec Savers or NZ equivalent.

 

Mini mania give no tightening torque for the studs.

Calver is referring to the torque of the  Nuts.

 

yes the studs are fitted hand tight.

 

I suggest getting a workshop manual.



#4 MiniMadRacer

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Posted 15 April 2022 - 08:48 AM

:lol: Nick is not subtle, but he is right...



#5 MiniMadRacer

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Posted 15 April 2022 - 08:52 AM

And the 1805 head (MK 3 S if I recall) has the bolt at the water pump end of the head, that should be 25 lbs



#6 Nootnoot11

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Posted 15 April 2022 - 12:43 PM

@nicklouse - Thanks for the info. I do have the yellow bible (3rd edition) and Haynes manual (1969-2001) but they don't mention stud torques or studs at all in section "2A" of the Haynes manual. What other workshop manuals do you recommend?

 

I think this information from Mini Mania below is why I thought they were talking about the studs.

 

"cylinder Head bolt (11 stud head) - 25 lbft"

 

I think what @MiniMadRacer mentioned helped me understand, my head is an 11 stud design and It seems hole 10 and 11 used bolts (on some model?), hence 25ft pounds for bolts, NOT studs.

 

Thanks @MiniMadRacer and @Ethel, hand tight it is.

 

Cheers team.


Edited by Nootnoot11, 15 April 2022 - 12:46 PM.


#7 nicklouse

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Posted 15 April 2022 - 01:58 PM

@nicklouse - Thanks for the info. I do have the yellow bible (3rd edition) and Haynes manual (1969-2001) but they don't mention stud torques or studs at all in section "2A" of the Haynes manual. What other workshop manuals do you recommend?

It does not matter as a stud can not have a torque figure applied to it and then only if it has a means to apply said torque.

 

just have a think about how many studs there are on the Mini power unit. A good fair few. More on the older versions and non of them are given a torque figure. The Haynes manual does mention using two jammed nuts to wind the studs out or in. Which is bad as if you are having to use force then the threads need looking at.



#8 Spider

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Posted 15 April 2022 - 06:21 PM

The Studs in to the block are hand tight, though, I like to just nip mine, perhaps 4 - 5 ft/lb at most.

There's some factory info on Head Studs here;-

 

https://www.theminif...studs-and-nuts/

 



#9 Ethel

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Posted 16 April 2022 - 06:16 AM

 I like to just nip mine, perhaps 4 - 5 ft/lb at most.

 

 

That's irritatingly thought provoking...

 

Could that put the end of the stud under compression & what effect would that have when you stretch it from the other end?

 

I'm sure it's neither here nor there with barely a nip, but it's a brain teaser.



#10 Spider

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Posted 16 April 2022 - 06:54 PM

 

 I like to just nip mine, perhaps 4 - 5 ft/lb at most.

 

 

That's irritatingly thought provoking...

 

Could that put the end of the stud under compression & what effect would that have when you stretch it from the other end?

 

I'm sure it's neither here nor there with barely a nip, but it's a brain teaser.

 

 

I think you could 'pull it apart' 6 ways in your mind !  I don't know that it puts the UNC end under compression, they aren't tightening up by bottoming out rather I'd say the very small taper at the finish of the thread on the shank of the stud.



#11 Ethel

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Posted 17 April 2022 - 10:14 AM

I went back to bed 'n thunked about it.  :shy:

 

Decided you can't  put a stud under compression by screwing it in from the opposite end. You're using the same side of the thread to make it go in.

 

I also decided "tap taper" would be the cause of resistance. That would put local (axial) compression on the thread, but only by loading the thread above in tension (equal 'n opposite). Way beyond my pay grade to decide if that'd be beneficial, but I can see how it might be by preloading the threads on the bottom to take a bigger share when the stud is stretched from the other end - asking most of the thread nearest the pull.

 

 

I don't think any of us would want an engine where it was remotely likely to matter.



#12 Tornado99

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Posted 21 April 2022 - 02:23 AM

Is there any benefit/risk for using anti seize on stud threads into a head or block?





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