Ausmini
It is currently Fri Mar 29, 2024 12:35 am

All times are UTC + 10 hours




Post new topic Reply to topic  [ 6 posts ] 
Author Message
 Post subject: Stripped head stud hole
PostPosted: Thu Feb 15, 2018 8:14 pm 
Offline
848cc
848cc
User avatar

Joined: Fri Jul 21, 2017 1:14 pm
Posts: 303
Location: Branxton, NSW
When re-torquing my head today, one stud thread in the block has started to pull! Not pleased. I guess I'll helicoil it but need to know if someone has any advice and especially is it a blind hole? Dont want metal in the engine

_________________
1972 Mk3 Mini 1000, 1150cc supercharged.
https://www.ausmini.com/forums/viewtopic.php?f=3&t=95872


Top
 Profile  
 
PostPosted: Fri Feb 16, 2018 5:24 am 
Offline
religious status
religious status
User avatar

Joined: Fri Mar 19, 2004 6:19 pm
Posts: 39621
Location: near Baulkham Hills, NSW
Yes it's a blind hole.
You can either helicoil it or tap 7/16" UNC for a custom made stud.
Either way, it needs to be done so the stud is dead vertical or you will have grief fitting the gasket. So I would not do it in the car unless you hire a magnetic base drill.
And use it also to start the tap square.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:


Last edited by drmini in aust on Fri Feb 16, 2018 6:43 am, edited 1 time in total.

Top
 Profile  
 
PostPosted: Fri Feb 16, 2018 6:40 am 
Offline
848cc
848cc
User avatar

Joined: Fri Jul 21, 2017 1:14 pm
Posts: 303
Location: Branxton, NSW
Thanks. is it 3/8" unc thread? I have heard use an old rocker post to get the drill square as well, mag base also an option

_________________
1972 Mk3 Mini 1000, 1150cc supercharged.
https://www.ausmini.com/forums/viewtopic.php?f=3&t=95872


Top
 Profile  
 
PostPosted: Fri Feb 16, 2018 6:42 am 
Offline
religious status
religious status
User avatar

Joined: Fri Mar 19, 2004 6:19 pm
Posts: 39621
Location: near Baulkham Hills, NSW
Yes it is 3/8 UNC.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:


Top
 Profile  
 
PostPosted: Sat Feb 17, 2018 5:28 am 
Offline
848cc
848cc

Joined: Fri Jan 02, 2015 3:59 am
Posts: 41
When drilling a block for 11 studs I used the cylinder head to get in right place. Plus some valve guides drilled out to 8mm internal and turned for sliding fit in the head drilling (note, there are different sizes depending on which one). The drilling was then just done using electric hand drill.

An old rocker post works well to keep the 3/8 UNC tap dead vertical, but it is too small for use with a 7/16 UNC tap or a 3/8 helicoil tap. Best used with an old rocker shaft and a second rocker post which you can clamp using spare 3/8 stud to keep from wandering about.

All lined up perfect, head slips on without touching the 10th stud - other one is the bolt at thermostat end which uses a 5/16 UNC helicoil.

But have not tried this with a stripped head stud.


Top
 Profile  
 
PostPosted: Sat Feb 17, 2018 7:21 am 
Offline
religious status
religious status
User avatar

Joined: Fri Mar 19, 2004 6:19 pm
Posts: 39621
Location: near Baulkham Hills, NSW
I made a custom stud once from a 1/2" UNC grade 8 bolt, I turned it down to 3/8 except at the bottom then threaded 3/8" UNF at the top.
Someone had already done a bad job of tapping the S block to 7/16", it was drilled and tapped crooked. Hence my comment above.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 6 posts ] 

All times are UTC + 10 hours


Who is online

Users browsing this forum: No registered users and 16 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  

cron

© 2016 Ausmini. All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.