The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: bikerboy on 10.03. 2026 16:59
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For some reason I simply cannot fathom virtually every time I roll one of my A10s out of the garage I need to tighten the bolts that hold the rocker feed on or they leak oil. I have tried new washers and dowty washers but they still need tightening every time anybody noticed this and found a fix?
A pic of my latest completed project, notice the twin carbs sneaking in lol
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Dunno about the leaky feeds - but amazing colour-co-ordination of exhaust pipes with the rest of it. *smile*
But seriously, what a nice beast. Goes, obviously stops, and is 'personalised pretty'. I like.
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This is typical, unfortunately. The correct fibre washers are very thick, so they compress and go hard, then they leak again, so you tighten them up etc, etc. Sometimes, if you're lucky, they'll settle down and be fine. I've never got round to doing any sort of modification, but this is something that needs a better engineered solution.
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Make sure the Acorn Nuts at the other end are doing their job and keeping the rocker shafts pulled nice and tight to the rockerbox casting. There should be a support washer between the shaft Thackeray spring washer and the alloy. This has the same ID as the shaft thread diameter, not the rocker shaft.
Swarfy.
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Mine has solid copper washers with blue Hylomar. Never been a problem with either leaks or coming loose.
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Yep, annealed copper washers for me, too.
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Thanks for the hints copper washers next.
Thanks Groily for the nice comment
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Annealed aluminium is my favoured choice. They use them for air fittings and they work harden so they tighten and stay tight they are softer than copper so put less stress on the fitting and can be reused by annealing.