center bolt for valve covers

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michael
Posts: 148
Joined: Mon Aug 30, 2010 12:24 pm

center bolt for valve covers

Post by michael »

Are all center bolts for valve covers on 1000cc airheads the same length and thread pattern?
Kurt in S.A.
Posts: 1577
Joined: Tue Aug 03, 2010 12:08 pm

Re: center bolt for valve covers

Post by Kurt in S.A. »

Appears to be the case. Using the part number 11120023160, it seems to cross many models:

http://www.realoem.com/bmw/enUS/part?id ... 1121744330

Snowbum talks about the acorn nut and threads at the bottom of this page:

http://bmwmotorcycletech.info/pushrodseals.htm

If the stud pulls out, it can be replaced with a longer all thread and loctited in place.

Kurt in S.A.
michael
Posts: 148
Joined: Mon Aug 30, 2010 12:24 pm

Re: center bolt for valve covers

Post by michael »

Thanks Kurt
barryh
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Joined: Fri Oct 01, 2010 12:30 pm

Re: center bolt for valve covers

Post by barryh »

There's no issue with the nut, it's the studs that are too short. Either replace the studs with longer ones or make sure the the stud fully engages all of the threads in the head and accept whatever threads are left for the nut. Steel in steel can cope with fewer threads better than steel in alloy. I've never put a torque wrench on one but It doesn't need to be much above finger tight, at a guess not more than 5ftlbs. I've never had one come loose at that or leak any oil.
barry
Cheshire
England
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jagarra
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Joined: Mon Dec 26, 2011 12:42 pm
Location: Reno, Nevada

Re: center bolt for valve covers

Post by jagarra »

When I pulled that stud on mine I noticed that the threaded portion was longer on one end than the other. I reversed the stud and installed the longer threaded end in the head enough to catch threads and gingerly tightened the other end against the cover.
1974 R90/6 built 9/73
1987 BMW K75S
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1964 T100SR Triumph
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Wobbly
Posts: 300
Joined: Mon Aug 07, 2017 8:48 pm

Re: center bolt for valve covers

Post by Wobbly »

I've seen photos where the stud hole was drilled on through. Then a steel hex nut was coerced into the open area between the rocker area and combustion chamber. (There's an existing hole at that location in the head.) A longer stud was then threaded into the hex nut so that the valve cover stud is pulling against the steel hex nut.

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ME 109
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Joined: Tue Aug 03, 2010 3:00 am
Location: Albury, Australia

Re: center bolt for valve covers

Post by ME 109 »

I thought all heads had the centre stud hole drilled though?
I'm running with just a centre nut plus silicone on one head to overcome head warp and oil leak. Leak stopped.
Lord of the Bings
barryh
Posts: 683
Joined: Fri Oct 01, 2010 12:30 pm

Re: center bolt for valve covers

Post by barryh »

ME 109 wrote: Sat Jun 16, 2018 12:51 am I thought all heads had the centre stud hole drilled though?
I thought so too. That's how I check all the threads are engaged by looking down the gap to see if the end of the stud is flush. As it came from the factory they weren't flush so I double nutted the studs and turned them in a bit.
barry
Cheshire
England
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