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Head bolt torque specs

gvr4ever

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Aug 6, 2002
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central Indiana
I finally got all the stuff in to put my car back together. I just wanted to verify that 80'lbs final torque was correct. They seemed way harder to break loose then that.

Also, should the threads have oil on them, or should they go in dry?
 

Barnes

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The bolts will be much harder to take out than put in. Generally oil will work its way to where the threads are, and over time it will coke up. It acts almost like glue.

I don't remember exactly what you have done to the engine up to this point, but I'll make a few suggestions:

Clean threads = accurate torques. Remember the factory put this thing together with everything clean as a whistle. If you are re-using your head bolts, clean them thoroughly! Lots of brake cleaner/carb cleaner or whatever that will break down all the old oil and coking. If new, just make sure any rust prevention coatings are removed. I can’t remember if they are just oiled or coated with anti rust liquid.
Clean the threads in the block thoroughly! These threads are nastier than you think. Lots of brake cleaner/carb cleaner and a bottle brush, rags, whatever. Just make sure if you use a bottle brush with wire bristles that they are fine, and preferably a soft material like brass. It will take a long time, but getting the threads clean is worth it IMO. Make sure you blow out the holes with compressed air to ensure no grit or leftover rag/paper towel bit remain. Clean the threads until a clean head bolt threads in and out nice and smooth with no resistance. These two steps ensure that the clamping force for each head bolt is as close as possible.
If you are using stock head bolts and head gasket (which I think you are?) you should follow the factory manual procedure. It probably tells you to oil the threads, which you should. Honestly, you should always lube the threads, and adjust torque to compensate if need be. If the manual says to oil them, and specifies a torque, use the torque they give applied using the pattern they specify. I recommend that after everything is clean, you put clean oil on the threads of the bolts and run them into the block a few times to make sure bolt bolt and block threads are nicely lubricated. Try not to oil *just* the bolt and put into the block with dry threads.

If I have time I’ll try to find the factory procedure/information.
 

gvr4ever

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I'm using new stock bolts, head gasket. It was my understanding that they stretched and were a one time use. I got new ones just in case.

I have to clean the block surface first, and I'll work on cleaning the block threads too while I'm at it.

At the moment, I just have some of the pdf scans on manuals that have been shared. I had the actual factory manuals, but they've been lost during a move or something.

I can't find instructions on using oil or not using oil, just the final torque spec and pattern to use. I was going to go at it in a three step torque process.
 

Barnes

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Stock 6-bolt head bolts are reusable. Stock 7-bolt head bolts are not, because they are torque-to-yield.

I'll try to find the factory info soon.
 

Street Surgeon

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Mar 3, 2004
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Omaha, Nebraska
Nm, torque kg, ft/lb

69 ft/lbs




 
Last edited:

Barnes

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Wtf. Two manuals I read show 65-72 ft-lbs, another shows 80ft-lbs. What the heck is going on? 80ft-lbs is all I remember.

All manuals seem to indicate that threads should be clean and dry. /ubbthreads/images/graemlins/dunno.gif
 

gvr4ever

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The scan I found said 80'lbs. I just wanted to double check. Wonder if one of them is a later updated manual. Anyway, I'm not in the biggest of hurry being Easter weekend and hanging out with fam, but the parts came in the other day. I might try and clean things up this weekend.

For now, I'll plan on no oil. I thought the point of oil was to ensure no binding on the torque, but if the manual states dry and clean, then that is what I will do.
 

Barnes

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Honestly, I'm confused that the manual doesn't specify oiled threads. However the general torqueing section at the front of the book seems to take into account that the bolts used throughout the car are zinc plated. Zinc plating acts to reduce friction. Reading through some engineering literature makes me think they shouldn NOT be dry-dry, just little bit oily.

Anyone else have specifics on this?

My guess is that if you clean the threads, get the threads a bit oily, and do 80ft-lbs you'll be a-okay. /ubbthreads/images/graemlins/dunno.gif
 

turbowop

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Apr 29, 2001
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Yakima, WA
Install some ARP studs using moly lube under the nuts and torque to 80ft/lbs. Problem solved. /ubbthreads/images/graemlins/grin.gif
 
Last edited:

prove_it

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I would add a tiny bit of oil to the threads. Factory FSM doesn't specify this. It's worth it. Don't soak them, just a drop will do. 80ft lbs is what I always torque factory bolts to and never had an issue.
 

Wizardawd

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Aug 7, 2007
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Franklin, NC
Don't forget to retorque after a few heat cycles.

Wiz
 

prove_it

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I thought that applied to studs and not oem bolts. I'm sure it's a good idea, but it's not like the factory ever did that.
 

Barnes

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It's a good idea for *any* fastener in a critical application. All bolts undergo local yielding due to imperfections in the bolt, threads, washer, etc etc. So after some time, creep will reduce the stresses in these localized points. This can lead to a reduction in bolt pre-stress, and ultimately its ability to remain in place. This also ensures all fastenser are torqued as close together as possible.
 

G

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Feb 24, 2004
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zompton
What head gasket are you using?
 
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