ARP Torques

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Mc Tool
Helpful or Confused
Helpful or Confused
Posts: 114
Joined: Mon Dec 31, 2018 2:29 am
Location: Thornbury New Zealand

Re: ARP Torques

Post by Mc Tool »

I only got up to 70 f/p ,I just got that feeling that something had passed its elastic limit but within 1/8 turn I got the wrench to pop ( warren brown 1/2" drive ), so I think ,as you say pull the head and have a look :)


I wish I was young again , Id be heaps smarter than the first time

garrycol
Knows His Stuff
Knows His Stuff
Posts: 527
Joined: Thu Jul 16, 2015 2:47 pm
Location: Australia

Re: ARP Torques

Post by garrycol »

Maybe the stud was not screwed in far enough and the release you felt was it starting to wind down a little more - remember they have to be in not much more than finger tight (cannot remember the actual torque) so if the treads were not totally clean or lubed the stud might have just needed a bit more.

Did you torque the head down in a three stage process? Is an absolute necessity.

However the beauty of studs you can just take them back out and do the process again - I would pull the ones you had issue with, as best you can check the threads and if they look OK - do a dummy run with a normal bolt to say 50 ft lbs and see if it is OK - if the threads are damaged the bolt should pull out - hey the threads were damaged any way.

In that pic of mine a crack developed from the water hole, through the head bolt hole and to the outer block - an angle grinder slot was made down the crack into good metal and then tig welded up from the water hole, in the stud hole and as you can see on the outside of the block. The engine builder used helicoils but these are only half as long as the threads in the hole and on the studs so when I torqued the stud up, the lot pulled out (70ft lbs) My mobile guy used a thread sert that was as long as the original threads and had meaty threads on the outside so lots of grip in the block.

Oh I have just realised that you have not mentioned what engine you are working on - if it is a 3.5 then you should be using ARP kit 124-4003 which is for the old Buick 215 and Rover 3.5. If you have a 3.9 to 4.6 you should be using ARP kit 157-4301 - these are a 10 bolt kit but have longer threads - if you use the 124-4003 kit in your 3.9 - 4.6 you do run the risk of pulling the studs out even though the torque is less at 70lbs vs 80lbs.

I think the later kit works OK on the earlier engines but I cannot conform that - however the early kit has 14 studs and the later 10 studs.

If you dont have them here are the instructions for both kits
https://cdn2.arp-bolts.com/instructions/124-4003.pdf
https://cdn2.arp-bolts.com/instructions/157-4301.pdf

Mc Tool
Helpful or Confused
Helpful or Confused
Posts: 114
Joined: Mon Dec 31, 2018 2:29 am
Location: Thornbury New Zealand

Re: ARP Torques

Post by Mc Tool »

Ya know sometimes I just :| . I have just finished pulling the heads off and removing all the studs with the intention of fitting the 10 x 2 to my 3.9 , so they are to short :roll: , cant be #ucked going back down to the cave and comparing the 3.9 head bolts for length :D , apart from that it was a good day. :lol:
I wish I was young again , Id be heaps smarter than the first time

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