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-   -   Re-Torquing Heads after Rebuild (http://forums.pelicanparts.com/911-engine-rebuilding-forum/854769-re-torquing-heads-after-rebuild.html)

agfours 03-06-2015 08:53 AM

Re-Torquing Heads after Rebuild
 
I know I'm asking permission here for a shortcut, which is not recommended, but I'll make my question either way to gauge the response on seriousness of my actions... :)

Last week I opened up the valve covers to do a valve adjust. There was a top end done about 10k miles ago, and this was overdue as a second valve adjust (did one at ~1k, but got clicky again soon thereafter). There was a bit of an oil leak from the 1-3 cyl bank, and so I decided to check the head stud torque specs... sure enough the nuts/studs were about 5-10lbs shy of 23.5lbs specification. The 4-6 bank were all in spec.

Now, for the shortcut...I didn't remove the rockers to get to studs/nuts #1-8 in the head diagram for torquing order (as specified in Bruce Anderson's rebuild book), but went ahead with retorquing studs #9-18 in order and pattern recommended. This means that the outside nuts/studs are in spec but the inside 8 could be undertorqued...but the perimeter nuts/studs are tight.

Will this be problematic? Any experience on this approach?

Flat6pac 03-06-2015 10:49 AM

Are you torquing the head nuts (10mm) Allen or the cam carrier 8 mm nuts?
Bruce

agfours 03-06-2015 10:53 AM

The head nuts (10mm) and Allen bolt heads - of which there are 18 total as specified in the cross torquing pattern for the heads.

smokintr6 03-06-2015 12:30 PM

Quote:

Originally Posted by agfours (Post 8518618)
The head nuts (10mm) and Allen bolt heads - of which there are 18 total as specified in the cross torquing pattern for the heads.

The head barrel nuts are 4 per cylinder, so 12 per side. Sounds like you may be talking about the cam carrier bolts

agfours 03-06-2015 02:07 PM

Er, um. Yes. The cam carrier bolts...just went back and looked again at the diagram with caption, and I evidently misread what I was tightening...so I actually just retorqued the cam carrier bolts. :o I must have gotten in a hurry and read right past it, not to mention not even taking notice of why the pattern of 'studs' was so haphazard and numerous... eek. :eek: Good news is that they were loose and I retorqued them but about 1.5lbs shy of spec. Also good news is that this is a first step before tightening the head studs. Guess I will be trying again next time I have the covers off....

Question remains, if the cam carriers are not retorqued with the inner nuts but only those accessable with the rockers in place, am I looking at issues...i suppose less serious given these are not head studs :confused:

MikeD 03-06-2015 02:48 PM

Well, the torque spec for those is 18 ft-lb so they were ok to start with and you over tightened the ones you could reach. I'd just leave it alone at this point.

smokintr6 03-06-2015 03:34 PM

I actually might be inclined to fix it. ..you want the cam to run true in the center of that thing. I wouldn't want a mix match of torque throughout. Could be over kill but the last top end I did we followed Waynes book using lock tite under the cylinders. The loctite set unevenly and the cam locker up tighter than a drum when we bolted the carrier down....so they are somewhat sensitive to variation. I'm not a pro builder like others on the board, so it's good to solicit other opinions.

smokintr6 03-06-2015 03:34 PM

I actually might be inclined to fix it. ..you want the cam to run true in the center of that thing. I wouldn't want a mix match of torque throughout. Could be over kill but the last top end I did we followed Waynes book using lock tite under the cylinders. The loctite set unevenly and the cam locked up tighter than a drum when we bolted the carrier down....so they are somewhat sensitive to variation. I'm not a pro builder like others on the board, so it's good to solicit other opinions.


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