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Cylinder Head Nuts

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philward:
One for the Metallurgists out there! I'm just about to re-zinc the cylinder head nuts ready for engine reassembly.
I have some Stainless Steel A2 DIN 6923 non serrated flange nuts and was wondering as to whether these would be suitable for the stress' put on these head nuts - I don't know the standard nuts tensile properties to be able to research a comparison table.
I don't want to fit the SS nut if the threads 'give' a little and affect the head seating
Whats your thoughts? (its bloody cold in the garage to be in there zinc plating!)

Skoti:
I find myself nodding my head as I read Oddjobs footrest bar experience.

I also discovered to my expense that stainless A2 grade stuff is bad for thread galling as it's easy to overtighten because you just don't get the same feel as you do with normal steel fasteners.
Of course it's just when you try and undo them again, that's when the shit hits the fan...

Anyway A4 grade stuff is the way to go for high stress applications such as footrests and engine mounts etc, A4 has a higher nickel content and most importantly contains molybdenum so no more swearing when trying to undo stuff.

Hope this helps

Skoti

Skoti:
This may or may not be that relevant regarding the question Phil has about A2 head nuts.

Some time ago I fitted a set of stainless head bolts to my 850 Commando which had been previously oil tight in the cylinder head area. I struggled with oil weeping in the pushrod area at the front of the head for ages after that, away to cut a long story short I had the original steel bolts re-zinced and fitted them back on -  problem solved.

   

K2-K6:
A useful discussion here http://www.volksbolts.com/faq/basics.htm specifically about A2 bolts.

As oddjob points out,  it's the stud on these engine that is stretched to tensile load as the nut is compressed. 

I was trying to find a definitive comparison, but getting the rating of the Honda originals is not easy.

Something nagging says I wouldn't use them unless I could find more about rating.

Trigger:
Not advisable to use S/S nuts on any head  ;)

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