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Discussion Starter #1
Yes, before anyone says it I know this is pretty unnecessary if the torquing method was done correctly but if you could just humor me I would greatly appreciate it.

I performed the an insert job (Norms) on my '99 Northstar. I used new head bolts and torqued down to 30 ft*lb and then the 180 additional degrees (60, 60, 60). Can someone tell me what the ft*lb value the bolts should be at a minimum, after performing this torque sequence? I want to merely CHECK and make absolutely sure that I am achieving some sort of a sensible minimum value. Would 100 ft*lb be a likely minimum value? I would like to check everything while it is still accessible.

Thank you.
 

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Master of the Dark Art of Diagnostics
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Re: '99 Northstar Torque Values

I used new head bolts and torqued down to 30 ft*lb
and then the 180 additional degrees (60, 60, 60).

that is the correct torque spec/method -

Can someone tell me what the ft*lb value the bolts should be at a minimum -
there is no such torque value -
head bolts are "torque-to-yield" -
that means the bolts are DESIGNED to stretch -

if you used new head bolts -
and you followed the method you listed -
the torque is correct -
leave the bolts alone -
 

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And as a general rule, NEVER take a torque wrench to a tightened fastener to "check" the torque. The only way to verify proper torque on a fastener is to loosen it and re torque. Not possible on a torque to yield bolt.
 

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Discussion Starter #5
Re: '99 Northstar Torque Values

Let me rephrase the question: Say a bolt was turned its last 60*, using a standard click-type torque wrench, at approximately what minimum torque value would the wrench turn the bolt before it clicked? For example it would click, but not move the bolt, at 75 ftlb, 80ftlb but at 85ftlb it started to move the bolt without clicking. I am not looking for precise numbers, just an approximate lowest value. I am sure the number is much different for 120 degrees than at 180 degrees, even with the bolt stretching.
 

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Nobody knows. There isn't a torque value spec to work off of. 180 degrees from 30 LB-FT is a lot. 40 more? 60 more? There is no answer. You could probably do some advanced math based on friction of the materials and thread angle and surface area, but I don't think anyone here is capable of that.
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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Re: '99 Northstar Torque Values

Let me rephrase the question: Say a bolt was turned its last 60*, using a standard click-type torque wrench, at approximately what minimum torque value would the wrench turn the bolt before it clicked? For example it would click, but not move the bolt, at 75 ftlb, 80ftlb but at 85ftlb it started to move the bolt without clicking. I am not looking for precise numbers, just an approximate lowest value. I am sure the number is much different for 120 degrees than at 180 degrees, even with the bolt stretching.
======================
Let me rephrase the question...................
OK - let me rephrase the answer -

there is no such torque value -
head bolts are "torque-to-yield" -
that means the bolts are DESIGNED to stretch -

if you used new head bolts -
and you followed the method you listed -
the torque is correct -
leave the bolts alone -

if you don't think you followed instructions correctly -
the ONLY way to be 100% sure -
would be to replace all the head bolts with new bolts -
and follow the directions you listed -

and YES -
there IS a chance you might damage the inserts when you remove the bolts -
or install the new ones -

I suggest you leave the bolts alone -
 

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Re: '99 Northstar Torque Values

JTraik, Please follow the procedure and don't try to second-guess the engineers.

Head bolt torque and degrees-to-yield is one thing; head stud nuts and washers total torque is quite another.

............. and there is a Technical Service Bulletin posted in 2010 that modified the degrees of turn on the final pass of OEM Northstar head bolts. Please read the entire TSB linked in this sticky thread ........

http://www.cadillacforums.com/forums/northstar-engines-system-technical-discussion/198220-northstar-ring-cleaning-procedure-proper-oil.html

This thread belongs in Engines; Northstar. You really need to study all stickys in any thread of interest. Timeless info that may update paper service manual info for which there is no update.

EDIT: This thread is germane ..............

http://www.cadillacforums.com/forums/northstar-engines-system-technical-discussion/644953-head-gasket-replacement.html
 

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Discussion Starter #11
Re: '99 Northstar Torque Values

there IS a chance you might damage the inserts when you remove the bolts - or install the new ones -
Could you expound on this statement? Do you have personal experience with the Huhn inserts being damaged when bolts have been removed? I went with the Huhn inserts because I felt they were the best possible solution to the root cause of the issue which I see to be the block threads themselves. I purchased them with intent to eventually do a full engine rebuild in the future.
JTraik, Please follow the procedure and don't try to second-guess the engineers.
Thank you for the info, I really do appreciate it and will be fully educating myself. However, not to be snide, but are we referring to same engineers who designed the original, flawed, method of fastening heads to the block? Or the engineers that, as a corrective action, delegated Timeserts to be the GM accepted solution to their initial blunder? A "solution" that evidently has shown to be only mostly, but certainly not completely, effective? Your one piece of information notes a different torque sequence for inserted blocks, however does that take into account differences in the type of inserts used? Especially since the Huhn inserts use a much coarser/deeper thread. Is this their next installment of correcting their blunder, i.e. the timeserts being pulled out?
 

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Your call, dude.

When the block metallurgy and fine head bolt thread problems surfaced the only fix on the street was the TimeSert from Time Fastener Company. Later, they developed the BigSert. Then Norm Huhn began his NS300L machining. Any of those inserts takes/took the original GM head bolt with the original and later torque + rotation settings. The 98 - 99 engines were the worst for head bolt hole failures - school is still out on whether it was threads, blocks, metallurgy, corrosion or a combination of all the above. The sticky threads on this forum's main page offer more insight. You might also want to study the entire Cadillac Technical Archive way up ^^^^ in the top black bar. Most of it was written by one of the Northstar Powertrain engineers.

Later, Jake Wiebe (NorthstarPerformance) and others began machining dedicated Northstar studs out of first-class materials using large, coarse thread block threads and fine top threads - those studs use specific torque settings; no degree of rotation settings.

You can also use ARP studs in NS300L inserts, which allows the use of fine thread nuts and hardened washers torqued to specific torque settings.

The GM engineers and those that developed the stud/insert systems did a LOT of destructive testing to arrive at their recommendations - we don't have that luxury, and so the "Don't second guess ......." advice.
 

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Discussion Starter #13
I am going to leave the bolts. If an engine rebuild is performed at a later date I might consider the ARP studs. Must have gotten lucky with my '99 block, made it to 150k on OEM assembly, the only way I confirmed failed gasket was I found coolant at the exhaust down pipe when I had everything separated for a steering rack install. Even at that point engine would not over heat and ran perfectly, coolant was minutely being lost but was getting worse.

While machining the block for the inserts the aluminum shaved and did not disintegrate. Tapping effort was consistent throughout. Can you comment on the allegation that inserts (particularly Huhn's) can be damaged upon bolt removal?
 

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Your new GM head bolts should have come with a blue or white thread sealant/locker applied to the lower portion of the threads. When you twist those puppies into their insert/block threads and heat is applied over time it sets HARD. There is then always the chance of partially backing out an insert during later bolt removal............ many members report that, when removing original bolts, one or more may "crack" as the sealant unsnaps.

Nothing to say you couldn't use Loctite on the insert block threads.

Studs are usually inserted finger tight with or without ??? Loctite ??? thread locker........... but they'll never have to be pulled again. Removing the fine threaded nuts and hardened washers is a piece of cake.
 

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Master of the Dark Art of Diagnostics
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Re: '99 Northstar Torque Values

Could you expound on this statement?
sure -
inserts fix the damaged threads -
but are NOT recommended for "high traffic" use -

Do you have personal experience with the Huhn inserts
being damaged when bolts have been removed?

no - not specifically Norm's inserts -
but - THIS is copied directly from their site -
Studs are typically preferred in race engines with extreme high compression,
and where the engine is constantly being torn down and rebuilt.
They also provide a more consistent torque load.

I felt they were the best possible solution to the root cause of the issue
which I see to be the block threads themselves.
I purchased them with intent to eventually do a full engine rebuild in the future.

you should have done a little more research -
read the FAQ's - specifically #6 on the HUHNSOLUTIONS site -
or asked here - before making your decision -

I GUARANTEE - if you asked here -
and stated you intended to remove the heads in the future -
EVERY RESPONSE - 100% - would have recommended using STUDS -
not ANY brand of insert -
 

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Re: '99 Northstar Torque Values

Interesting, in my research prior to this repair I did come across FAQ #6 from Huhn, which he states:

"Absolutely. ARP® brand head studs are excellent, well engineered, high performance studs with rolled threads, that will work very well with the NS300L™ insert, in fact, I believe you will find no better combination on the market for high compression, high performance Northstar engines. Studs are typically preferred in race engines with extreme high compression, and where the engine is constantly being torn down and rebuilt. They also provide a more consistent torque load."

Not sure why you felt necessary to leave the first half of his opinion out of your quote... My thoughts, as confirmed by Huhn himself, is that properly repaired thread holes in the block (with the best possible insert, presumably Huhn's design) in combination with a stud is the superior solution. In other words (Studs + Threadlocked Inserts) > (Studs alone). However, no one can prove sufficiently either way.

I went with OEM bolts only because I had some crazy fantasy that I was going to be able to do this in the vehicle. That did not happen, so here we are today.

Lets discuss some possible scenarios upon OEM bolt removal with Huhn inserts. The way I see it, the thread locker on the inserts could break loose when removing the bolts due to thread locker on the bolts being the stronger force. In such an event, either:

1 - Insert backs out entirely WITH the bolt. In such a case the block threads can be cleaned and insert (maybe a new one) is reinstalled.

2 - Insert partially backs out and remains in the block. In such a case the insert installation tool can be used to remove the insert. Huhn inserts are not a "wedge" or "jamming" type but rather held in place with thread locker only. Then, again, block threads cleaned and insert reinstalled.

Any other possibilities?

----------

Studs are usually inserted finger tight with or without ??? Loctite ??? thread locker........... but they'll never have to be pulled again. Removing the fine threaded nuts and hardened washers is a piece of cake.
How can you deck or otherwise machine the block with studs in place?
 

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You cannot deck the block. And in my opinion there's no way an insert of any kind will outlast or perform a stud. Inserts are only used for repairs, if they were the best solution then they'd put inserts in everything from the get go.
 

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Master of the Dark Art of Diagnostics
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Re: '99 Northstar Torque Values

Not sure why you felt necessary to leave the first half of his opinion out of your quote..
it's not pertinent -
and inserts would not be needed if you used studs -

-----------------------

Lets discuss some possible scenarios upon OEM bolt removal with Huhn inserts.
1 - Insert backs out entirely WITH the bolt.
THAT couldn't happen -
the insert is larger in diameter than the bolt hole in the head -
so the insert couldn't possibly back out all the way -

BUT - it COULD back out until it contacts the head -
then what?

the OEM head bolt has thread-locker on it -
and the bolt/insert turns freely - up to the head -

IF the top of the insert contacts - and digs into the head -
it MIGHT cause enough resistance
to break the head bolt thread-locker loose from the insert -
so the insert stops turning - and the bolt turns out of the insert -
this is probably "wishful thinking" - and it wouldn't be that "easy" -

so - what if that doesn't happen - and the head bolt thread locker holds -

continue turning the bolt/insert until the aluminum threads strip out -
then pull the bolt/insert out with the head - in this case the block is ruined -

or possibly cut the head of the bolt off -
and lift the head off - then unscrew the remaining insert/bolt -

------------------------

2 - Insert partially backs out and remains in the block.
Huhn inserts are not a "wedge" or "jamming" type
but rather held in place with thread locker only.

similar to the above problem -

if the thread locker of the insert doesn't hold -
but the thread locker of the head bolt DOES hold -

how are you going to remove the bolt/insert past the head?

=========================

How can you deck or otherwise machine the block with studs in place?
you CAN'T deck the block - OR machine the heads -

if either is warped beyond a few thousandths of an inch -
the ONLY solution is replacement of either the block or head -
 

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Re: '99 Northstar Torque Values

Any other possibilities?/QUOTE]

Sure - an insert cannot "back out" any farther than the cylinder head gasket surface: The cylinder head bolt holes are too small for the outside diameter of the repair insert to pass through.

"Deck the block" - from the GM/Northstar service manual: If the cylinder block deck surface is warped more than .004", replace the block.

I.E.: No deck work allowed. .004" is pretty slight departure from flat.

Northstar blocks do not get machined for deck, bearing, halfcase, oil distribution manifold, piston ring hone, or cylinder liner problems - you replace the block. Just like your old cellphone - chuck it and start over.

Remember: Time Fastener, Norm Huhn, Northstar Performance, ARP, etc., etc. are in business to sell product. It's up to YOU to do the homework and decide the best "fix" for your application.

You really need to study the correct GM service manuals for your engine - that's the bottom line. Absent that knowledge you're flying blind. ("deck the block") School of hard knocks ? Yes. But we're all in the same boat.
 

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Discussion Starter #20 (Edited)
Re: '99 Northstar Torque Values

Sure - an insert cannot "back out" any farther than the cylinder head gasket surface: The cylinder head bolt holes are too small for the outside diameter of the repair insert to pass through.
In such a case, back out as many bolts as possible, elevate head from deck and continue to back out the partially removed bolts. The head should elevate away from the deck a distance equal to the deepest, stuck, insert distance. In any event, it is impossible to get the bolts stuck from being completely backed out of the block, UNLESS, the bolt snaps inside. A broken bolt would be a real problem... however, I don't really see that happening.

"Deck the block" - from the GM/Northstar service manual: If the cylinder block deck surface is warped more than .004", replace the block.

I.E.: No deck allowed. .004" is pretty slight departure from flat.

Northstar blocks do not get machined for deck, bearing, halfcase, oil distribution manifold, piston ring hone, or cylinder liner problems - you replace the block. Just like your old cellphone - chuck it and start over.
Is this because of the steel cylinder sleeves? They are pressed in from the top, can you access them such that they can be pressed in the opposite direction? What about the concept of inserting an enlarged sort of extractor tool to grip onto the sleeve and twist/pull out? Can new sleeves be purchased from GM or otherwise as a standardized part? What are sleeve dimensions?

What is the availability of NOS or remake blocks? Are there any aftermarket companies casting these older designs? Is GM still casting them?

Just curious on these things for the most part. Thanks.
 
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