Head acorn nuts always need retorqued

[vorhese]

I've got a freshly rebuilt top end. I have run through a series of torques and break ins. I replaced the 4 outer washers with thicker copper washers. The inners are still steel. I checked the compression recently and was getting 120 left, 140 right, so I decided to do another torque and valve job. As I'm torquing the acorns to 30ftlbs, It seems half of them (some copper, some steel washers) are loose every single cycle. Sometimes up to 1/2 turn before it clicks. That torque wrench should click right away every time. Any idea what's going on?


On one of them, as I was slowly torquing, it got REALLY loose and I thought for sure I stripped the threads. I decided to take the nut off and look, didn't see anything. I tightened it back up and it seemed to hold torque. Went around another sequence and it's slightly loose again.


I was reading somewhere not to put the acorns on dry threads, which I'm pretty sure i did. Could this be the problem? And how safe would it be to loosen each nut, one at a time,and put some grease or anti seaze on the threads... think that would solve it and not compromise my head gasket??

thanks for listening to my slight freakout.

 

[gggGary]

I am big on using anti seize. I have successfully removed the nuts one at a time, lubed replaced and torqued on at least ten engines now. Probably best to do an inside to outside pattern and don't forget to check the 2 under the spark plugs.

Recent 18K mile engine I did; the under the spark plug bolts and 6mm above the chain tensioner weren't even finger tight.
But something seems wrong on yours being constantly loose are you sure of your torque wrench? 30 pounds is a good solid pull out 12" from the nut.

 

[vorhese]

I've built 2 other engines this year and I think the torque is giving me good numbers. All the other bolts on the head are always correctly torqued and never need tightened, just the acorns. I'll put some anti-seize on, and try again. Report back.

 

[retiredgentleman]

Are those acorn nuts from Mikesxs by any chance? Everything they sell seems to be sub-standard and a poor fit. I would be very suspicious of those nuts. Either they are really poor quality threads i.e. wrong size, or they have been over torqued so much they are partially stripped.

Why don't you try using some new nuts, even just regular nuts to see if they will hold the torque without loosening.

 

[azman857]

My Acorn Nuts are bone stock and I just did a second or 3rd head torque after my recent rebuild. All of the nuts or bolts were a touch loose. Some looser than others. It's normal head gasket crush as heat cycles does its thing.Air cooled Beemers need regular head torquings too.