The funny thing about all this is that the factory GM bolts are generally very high quality...
but not as high quality as the ARP bolt which is rated at 180,000 psi breaking strain (they even do one rated at 220,000)
Broken Helicoil in block to head thread
Started by
_zooma355_
, Jun 17 2013 10:36 PM
43 replies to this topic
#26
_Mint_
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Posted 20 June 2013 - 06:38 PM
#27
_oldjohnno_
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Posted 20 June 2013 - 07:15 PM
but not as high quality as the ARP bolt which is rated at 180,000 psi breaking strain (they even do one rated at 220,000)
True, but in those cases where a factory bolt is entirely adequate (and there are lots of those) then an aftermarket bolt is no improvement at all, no matter how many psi's it has. And if the length isn't quite right or there's some other problem it's just a step backwards that you paid good money to take.
I guess what I'm trying to say is that 50 years ago blown fuel engines stayed buttoned up with plain old OEM bolts (not even studs) and now we have kids thinking they need 200,000lb ARP gear holding their engine together, right down to the anodized rocker covers...
#28
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Posted 20 June 2013 - 07:37 PM
True, but in those cases where a factory bolt is entirely adequate (and there are lots of those) then an aftermarket bolt is no improvement at all, no matter how many psi's it has. And if the length isn't quite right or there's some other problem it's just a step backwards that you paid good money to take.
I guess what I'm trying to say is that 50 years ago blown fuel engines stayed buttoned up with plain old OEM bolts (not even studs) and now we have kids thinking they need 200,000lb ARP gear holding their engine together, right down to the anodized rocker covers...
i understand what your saying johnno...but i personally am not going use an old rusty/corroded bolt thats been clamping a head down for 20+ years
#29
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Posted 20 June 2013 - 07:44 PM
Yep i totally agree , the stock bolts are of excellent quality and will do the job many times over if they aren't over tightened .Stock bolts are designed to stretch approx .004"-.006" at the specified torque and it is this stretch that clamps down and stops them coming undone . When u use higher tensile bolts such as arp in your conrods for example you will need to torque up higher to achieve the same stretch ,this is not a bad thing as long as the required stretch is achieved .
True, but in those cases where a factory bolt is entirely adequate (and there are lots of those) then an aftermarket bolt is no improvement at all, no matter how many psi's it has. And if the length isn't quite right or there's some other problem it's just a step backwards that you paid good money to take.
I guess what I'm trying to say is that 50 years ago blown fuel engines stayed buttoned up with plain old OEM bolts (not even studs) and now we have kids thinking they need 200,000lb ARP gear holding their engine together, right down to the anodized rocker covers...
#30
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Posted 21 June 2013 - 08:51 PM
that looks like a broken heli coil in the bottom section of that hole to me.
#31
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Posted 21 June 2013 - 08:56 PM
and the stretching of any bolt is called - Elasticity
every bolt as it's Elasticity Limit, and once you pass that the Bolt is Stuffed
Edited by TORYPOWER, 21 June 2013 - 09:00 PM.
#32
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Posted 21 June 2013 - 09:03 PM
You got it
and the stretching of any bolt is called - Elasticity
every bolt as it's Elasticity Limit, and once you pass that the Bolt is Stuffed
#33
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Posted 21 June 2013 - 09:06 PM
Thank-you Mick,
Got something right for once. Dave I
You got it
#34
_zooma355_
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Posted 23 June 2013 - 03:28 PM
Thx for all the replys guys it has been really helpful, just a quick update on the issue. The thread dmg was from previous builders but my bad in not noticing it b4 hand. There was no sign of thread material on the head bolt once i pulled it back out and my diagnosis is that it was a helicoil that wasnt installed properly. Anyway i put a new 1 in and the head torqued up ok, so cool bannanas!
Although threww my new adjustable street terra rockers on and the clearence between the spring retainer and the outer edge of the rocker is super close. Any major issues with this? I knew i might need to take a bit from the underside of the rocker but anything else i should be aware of? Also i had to throw two spacer washers under the rockers and had to adjust them all the way out to get the right preload. Length of push rod? or is this ok?
#35
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Posted 23 June 2013 - 05:54 PM
G'day mate,you need to check all clearances between rockers ,retainers and pushrod cups . The pushrod length may be a bit long due to block and head machining but if the roller contact patch is somewhere near the centre of the valves and everything else clears (including the rocker cover) then it will all work ok.
#36
TerrA LX
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Posted 23 June 2013 - 07:44 PM
Glad to hear you saved the block.
A paper clip is good for checking any potential issues with binding on the valve train.
#37
_zooma355_
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Posted 23 June 2013 - 10:05 PM
G'day mate,you need to check all clearances between rockers ,retainers and pushrod cups . The pushrod length may be a bit long due to block and head machining but if the roller contact patch is somewhere near the centre of the valves and everything else clears (including the rocker cover) then it will all work ok.
Sorry mate what clearances am i checking for at the pushrod cup?
Glad to hear you saved the block.
A paper clip is good for checking any potential issues with binding on the valve train.
thx mate, paper clip bout as close as ya wanna get? Mine might be a bit closer than that! 
#38
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Posted 24 June 2013 - 09:04 AM
You can measure your paper clip? They are usually about 40thou, you don't want to really go under that unless you are super confident there will be no issues.
#39
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Posted 24 June 2013 - 07:26 PM
Ok , When the valve is at max lift check that the pushrod is seated in the pushrod cup insert in the rocker and that the pushrod is not touching the rocker .A paper clip clearance will be more than enough .You need to check this and ensure the roller tip contact patch is near the centre on every rocker .
#40
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Posted 24 June 2013 - 07:51 PM
^ and check for spring bind while your at full lift.
#41
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Posted 24 June 2013 - 08:08 PM
something seems wrong there...the grub screw poking out the top of the rocker lock nut is odd..and i see you used ARP supplied bolt washers?
#42
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Posted 24 June 2013 - 08:11 PM
The Grub Screws are on their last thread, need shorter studs, or wind the barrel nut higher.
Edited by TORYPOWER, 24 June 2013 - 08:16 PM.
#43
_zooma355_
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Posted 24 June 2013 - 11:51 PM
something seems wrong there...the grub screw poking out the top of the rocker lock nut is odd..and i see you used ARP supplied bolt washers?
rockers arnt adjusted up mate, bought shorter trend rods today and was able to cut down to 1 spacer and wound the grub adjustment rite down to less than half way. And yeah i did use the washers mate, no good?
#44
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Posted 25 June 2013 - 08:30 PM
rockers arnt adjusted up mate, bought shorter trend rods today and was able to cut down to 1 spacer and wound the grub adjustment rite down to less than half way. And yeah i did use the washers mate, no good?
hi matt...all good with the rockers then..yeah as i said in a earlier post that i used the ARP bolt set on my 308 an found using their washers made the bolts about 10mm shorter than the original Holden head bolt..at least on all the long ones so i didnt use them.
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