Stripped rocker pedestal nut

Side valve, 803, 948, 1098., 1275 and Vizard mods

Re: Stripped rocker pedestal nut

Postby mark wilson » Wed Dec 14, 2016 8:15 am

Thanks, I did wonder about the lubrication effect of Loctite, so I'll omit it. I changed the studs as I didn't know the history of the engine and the originals looked past their best, but I'll dig them out and see if they have the high tensile markings Phil described. I've already ordered replacements - from a different supplier!
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Re: Stripped rocker pedestal nut

Postby philthehill » Wed Dec 14, 2016 9:09 am

Mark
Having checked your torque wrench and found it to be in tolerance thankfully that is one source of the problem that can be discounted.
Back to those spring washers:-
The original spring washers fitted under the 'A' Series rocker pillar nuts were of a very flat profile and the upper face of the spring washer (which had an O.D. of 4.8mm and depth of 2.2mm) was covered by the whole of the under side of the 5/16" UNF nut. The max cross dimension of the original 5/16" UNF nut is 4.4mm.
The original 5/16" washers fitted to the 'A' Series can be identified by a light knurling on the outside edge.
The majority of 5/16" spring washers supplied today are of a square 1.7mm profile with an outside diameter of 2.15mm. They are not suitable for this application because as mentioned above they can and do distort under pressure. The original spring washers do not distort and therefore are suitable for this application.
I would suggest that you fit the original type washers and torque to 25lbf ft un-lubricated.
I would also suggest that BMC/BL fitted those washers for a purpose and they should not be discarded.
Phil
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Re: Stripped rocker pedestal nut

Postby mark wilson » Sat Dec 17, 2016 11:31 pm

All now torqued up ok with new rocker studs and nos BMC spec nuts and spring washers. Cause of problem still not definitely identified, but quality of studs and washers still a prime suspect. There was, though, some slight contamination of the threads with copperslip (which I'd used on the UNC threaded ends), so this may well have contributed to the problem. Carefully cleaned it all up before .retightening - but applying the final torque to the rocker studs was a real test of my nerves!

Thanks for all the advice, really appreciated

Mark
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Re: Stripped rocker pedestal nut

Postby The vast minority » Sun Dec 18, 2016 6:37 am

A happy ending to a thread, that's a great result then

Al
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Re: Stripped rocker pedestal nut

Postby Panky » Sun Dec 18, 2016 11:20 am

The vast minority wrote:A happy ending to a thread

Al



Happy ending to a stripped thread :)
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Re: Stripped rocker pedestal nut

Postby philthehill » Sun Dec 18, 2016 11:38 am

Mark
Well done.
Did you determine the type of cylinder head studs fitted i.e. the high tensile type with their identification symbol as posted above?
Phil
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Re: Stripped rocker pedestal nut

Postby The vast minority » Sun Dec 18, 2016 2:10 pm

Panky wrote:
The vast minority wrote:A happy ending to a thread

Al



Happy ending to a stripped thread :)



Belter :x
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Re: Stripped rocker pedestal nut

Postby mark wilson » Sun Dec 18, 2016 4:25 pm

philthehill wrote:Mark
Well done.
Did you determine the type of cylinder head studs fitted i.e. the high tensile type with their identification symbol as posted above?
Phil


No markings on either the head studs or the rocker studs which the engine came with, so I stuck with the new head studs and the second set of new rocker studs.


Panky wrote:
The vast minority wrote:A happy ending to a thread

Al



Happy ending to a stripped thread :)


Great stuff!☺☺

Mark
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Re: Stripped rocker pedestal nut

Postby philthehill » Mon Dec 19, 2016 7:28 am

Mark
Thanks for the reply.
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