The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: spottycat on 05.06. 2024 11:18
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Hi - I have tried to remove the sludge trap plugs from my 1961 A10 using all the techniques people talk about in the forum. Alas, I can not budge them. My local engineering shop can bore them out for me but they want to know the thread size before doing so. I have searched the forums but not found the answer. Can anyone tell me if the size and if it is a whit or BSF thread please? Cheers, Chris
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i seem to think they are 7/8ths 11 tpi someone will be along to correct me if this is wrong.
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Many thanks
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Plenty on the Forum to see how other folks do it. New plugs are available, sacrificing the originals is a shame but If you need to be a bit brutal after pussyfooting with.....
Drilling the plugs, not the crank, to remove the factory punch locking pips....
Using a well fitting driver with a wide blade (slot type) or hex key.......and an impact driver set to undo!
Giving the driver a good smack with the lump hammer.....to shock the thread.
Applying heat with a blowtorch......to soften any locking compound, expand the metal, get even!!!!
Welding a nut onto the plug......
Still stuck? Best sharp drills at the ready, time to show who's boss, start by drilling a hole accurately into the plug centre, then increasing the hole diameter until you are left with just a defeated threaded cylinder which can be collapsed inwards leaving the original crank threads to receive new plugs.
I would have thought for initial professional assessment the size of the plug core was clear to anyone familiar with nuts, bolts and threads. Nor would I expect them to machine away the existing crank thread so no aftermarket plug would fit.
Swarfy.
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7/8 BSF. I got a tap off e-bay for about £5. They may have one.
Oddly BSF is 11 tpi and BSW is 9 which hardly seems worth the bother *conf*
The sludge trap tube is probably jammed in so order one of those if you haven't, one plain plug and one with a spigot and double and treble check you put them in round the right way... Locktite is fine, no need for huge centre punch marks. The A65 is locktite and (correct me guys) no one in the history of man has has one undo.
Worth getting three flywheel bolts while you are there. Yes it all adds up *smile*
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G'day Spotty.
When ordering new plugs get the ones with the hex. Makes the job next time so much easier DAMHIK! https://draganfly.co.uk/shop/55405/sludge-plug-hex-socket-large-journal-78-bsf/#10404-58A
https://draganfly.co.uk/shop/74560/sludge-plug-hex-socket/#67-1212A
Pitty they don't make them for the small journal cranks.
Cheers
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https://www.a7a10.net/forum/index.php?topic=18484.msg160141#msg160141