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torque for Head bolts -- solution found

36K views 40 replies 20 participants last post by  stubadub 
#1 ·
Hi,

Last weekend I started to rebuild my engine (4.6). In the shop manual I found that the head bolts should be torqued at 20 Nm and then 90 degrees and again 90 degrees.
I 've fastened them on 20 Nm and after that 90 degrees. But I really had to put a lot of force on them to get those 90 degrees (using a tube to get a longer wrench!!). Is there a printing mistake in the shop manual or do I have to ask the Hulk to come and help me with the other 90 degrees?


The Manual said:
* Cylinder head bolts:
- Stage 1 - 20
- Stage 2 - Tighten further 90°
- Stage 3 - Tighten further 90°
I remember that for the RRC, that has the same block and heads, there was no degrees, only torque values in the shop manual.

Could I leave it as it is with 1 time 90 degrees after the 20 Nm? I am affraid to break the bolts if I go any further but at the same time I know how important the torque on heads is and if the book says 2 times 90...
(I don't feel too good about it)
Any expierience?

thanks
 
#27 ·
15lbs is marginally over finger tight, my 110lbs torque wrench doesn't even go down that low. Although if using the stud kit rather than stretch bolts, I go 35, 50, 65lbs/ft, done. Problem you have with stretch bolts these days is that you have no way of knowing if they are made to the exact spec of the originals. If they are softer they may stretch too much or even break, if harder they may pull the threads out of the bloc. Even if you buy genuine Land Rover ones they still may not be identical spec to the ones they supplied 15 years ago.
 
#31 ·
You've only done head gaskets?
No moving parts to bed in so, assuming you've built it right, straight out of the box!
 
#33 ·
I should drive it for a week or so (to give it the chance to cool down at regular intervals) just to make sure all the air is out before relying on it's max cooling capacity when towing.
 
#34 ·
Noted. I'm keeping an eye on things like a hawk right now and driving easy. The main reason I asked is BC at some point yrs & yrs ago I heard something about not flooring a vehicle outta the factory or with a new head gasket till around 1k miles to let things settle.
 
#35 ·
If it's a new engine or one that's got rebuilt components you do need to treat them gently initially to wear the machining marks off everything and let it bed in. Equally, back in the days before composite head gaskets you had to re-torque them after a few hundred miles but you don't need to do that with modern ones. As Ferryman says though, drive it gently and check fluids regularly just in case you've caused any leaks or air locks by having it apart but if everything is staying as it should, then just use it.
 
#37 ·
Its strange when some have good experience with torque to 60-65 ft/lb, why go to 100 ft/lb. In my recently bought ARP kit the instruction still say 80 ft/lb. I`ve heard horror stories of people stripped the treads on much less than a 100 ft.
I`ve installed now with 100Nm equals to about 75 ft/lb, as I`ve read the recommandation from Martin and RRToadH wich I think they seems to know what their talking about:thumb: and I was terrified even when pulling to 75ft/lb:pray:.

Should I dare to pull the last 25 ft - trying to reach a 100 ft/ lb?

I Still have access since Im in the prosess of shimming the rocker pedestalls to get the recommended rocker preload on my new cam / lifter setup.

Seems to be so very big difference in the recommandation regarding torque settings on these studs, stretching from 60-100+ ft/lb - reading this forum and Aulro forum on the matter. Actually makes me a little confused:think:, so I tried to relate to the recommandation / installation instructions that came in the box with my kit saying ( 80 ft/ lbs ) but as I said, I chickened out at 75 ft/lbs8~.

How do you know if the stud is turning in the block or if you turn the nut on the stud - when your at this high settings?

- By the way the Elring head gasket torque recommandation for a classic installation ( same engine almost ) is 95Nm ( 70 Ft /lb )- that also why I considered 100Nm would do it.


Brage
 
#38 ·
WHatever you do, how ever you set things, DO NOT use the printed directions that come with the stud kit. It does indeed call for 80lbs. Yes, it is possible to strip your block threads. 100 would be suicide. With the composite gaskets there is absolutely no need to go above 65-70lbs. THis takes into account miscalibration of wrenches, poor assembly lubrication practices etc. The goal is not torque to an exact spec but EVEN torque across the face of the head.

As far as turning the stud during torque... a properly installed stud will be bottomed out in a dry hole. it will be impossible for the stud to turn. Likewise you should be placing your dry head washers on the studs and only then placing assembly oil on the mating surface of the washer and exposed threads. This give a single low friction point at the washer and nut to ensure even torque readings.
 
#41 · (Edited by Moderator)
Just for the record since I've read about everything at this point & to be honest prob to much before I did my head job cause I was half scared of what "could" happen here's what I did.


Minimum, Britsh Atlantic head bolts for $90 (I strongly recommend to not buy junk for $50)

I did NOT use a 16mm at some mentioned, bought two new ones and they seemed sloppy and slipped on me almost immediately (factory bolts in head), used a new 5/8 and had zero issues. Keep your socket firmly planted or you will regret what will happen.

Blew the head bolt holes out w/ compressed air and inspected each.

Did NOT make sure every single one was spotless and clean beyond clean as some have mentioned doing. Just blow it out and make sure it's clean. Not that spotless isn't nice, just saying.

Lightly lubed the entire bolt, bottom, threads and under the edge as RAVE mentions. I did NOT heavily oil the bolts as that could lead to a nice hydrolock and more regrets.

Torqued Gently to 15lbs (make sure your bar will click this low).

Marked all bolts at 12 o'clock. Mark them where ever u want really, just don't forget where u started.

Turned each bolt with a breaker bar in the correct sequence 90 degrees or say 3 o'clock.

Waited 25-30 mins and prepped the other head and then turned the remaining 90 degrees. 0.0 issues.

I only used a 16 inch pipe on my breaker bar. Although hard to do I turned the last 90 with my left hand on at least half the bolts, kinda all depends on how your socket lines up.

I then put 150 miles on it all the while checking my oil, coolant & underside like a hawk before promptly loading up at least 4k lbs worth of boat, trailer, two 90lbs dogs, two friends + gear. Drove for an hour and a half with no issues and zero leaks when I got back home on Sunday.

Following the directions does wonders most times.
 
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