BSA A70L Lightning - Fixing Head Gasket Leak - Part 1
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- Опубліковано 16 сер 2020
- Following last stable update, we know the A70 head gasket is leaking, so let's find out the cause and get it fixed. Warning - contains some engineering that may not be approved by all!
- Фільми й анімація
You can see where it was blowing into the pushrod tunnel and pressurizing the bottom cases.
As per my previous guess. Angus.
Thanks Roy I was wondering how it might be pressurising crank and that’s the answer.
a good rainy day's work Angus, just keep those cups of tea coming and save the beer till the workshop's cleaned up.
Definitely Peter - many thanks.
If you put the glass plate on your table and the head on top it will grind allot essayer .good vid
Why didn’t I think of that? Seems so obvious now you’ve pointed it out. Thanks for the comment and interest.
I admire your tenacity
Thanks Richard - well it's gotta be sorted. End of. Before Stafford - hopefully.
Don't forget to unload your torque wrench when you aren't using it.
Very good point John and one I usually forget, like many others no doubt. Thanks for interest and comment.
leaving it loaded up weakens the spring on the torque wrench and it'll give you a false readings, might be a good idea to re check with a new calibrated torque wrench. I made some thread inserts on my small lathe as an experiment to re thread the rocker box on my B44, made a 5/16 bar, drilled and tapped 1/4 BSC, threaded the outside 5/16 BSC, cut to length and then installed in the cylinder head, worked a treat, seemed to be more substantial than a recoil, only time will tell. I lime the bike collection by the way, there very nice. Keep up the good work.
Thanks David - very kind. I’m not an engineer and wouldn’t know one end of a lathe from another let alone how to operate it. So I have to use commercially available kits and ensure they are fitted properly. Thanks also for following up on John’s tip re torque wrench.
looking good m8 best of luck 😜👍
Many thanks Mick for the interest and continued moral support.
First time I've seen the glass method. Is that how it's often done then?
Hi Mark - yes - I was taught this in the 1970's when I had an A65L then with the same problem. Others have commented too, but suggested to put the glass on the bench and the head on top of that. Simple solution for home without having to have a mill to skim it.
Another good video, don't forget you can get different lengths of coils, longer the better in certain applications, you could have borrowed my new snap on torque wrench instead of the knackered old thing from ww1 lol, hopefully that's the engine about sorted now. What's next...
Excuse me Matt it’s from WW2 lol. Next up - finish reassembly, fit new points/backplate, time up and away we go. Possibly. Thanks as always. Get your welder ready for the Fury SS Silencers.
You will have to teach yourself to weld, you can borrow it, I am far to busy...that's another video in it's own right??
Deal mate. When the A70L is running. Properly. Cheers.
Cool,no probs,only if you chuck them old torque wrenches in the bin. lol..
It’s the user, not the torque wrench, that’s the problem.
Coils of the right length should be fine, especially with a bit of Loctite thread seal. Rather shocking though that the guy that fitted the sleeves didn’t flag that the stud holes were dodgy. Not part of the job he was asked to do, I suppose, but surely he’d check that the barrel is completely sound before starting work on fitting the sleeves (?)
Thanks and yes I’m a little surprised too that the issue wasn’t noticed/flagged up, but then I didn’t spot either when first inspecting barrel - too focussed on how to resurrect bores.
Angus D. Campbell Thanks for the reply and for your channel too. Great to follow your honest efforts to keep these machines alive, warts & all. I’ve been running old BSAs for 40 yrs, incl. a ‘63 Lightning Clubman. Many good times & mistakes too 😎
Many thanks - appreciated. That's exactly it - good times including free mistakes.
Interested to know how did your 1 year old T160 last ❔
Hi Peter - well it provided sterling service for a couple of years commuting until at 12,000m one of its big end bolts came undone. Common problem. Rebuilt it and kept it for a few more years when it shared a stable with a new T140D Bonny until I sold it to one Clive Humphries prob in about 1983 I think.
@@BSAPowerSet - thanks ✅
Looks like someone has probably overtightened the head nuts in the past. Nothing which can't be fixed.
My experience of helicoils is good (in the marine industry), often stronger threads than the original material.
Thanks Thomas that's reassuring. I've read that good helicoiling can be stronger but I know there are those that wouldn't entertain that type of approach. Each to his own and in my case, securing another set of serviceable late barrels will be difficult and wouldn't necessarily cure all the ills without stripping the whole lot again. Which I'll do if this fix turns out to be inadequate.
My experience of helicoils is good and I have found them stronger. However, the accuracy of the thread of the fixing and its amount of play can be a factor for failure IMHO.
Thanks Ian - agreed.
@@BSAPowerSet As an apprentice in the aircraft industry, I remember we used Helicoils on new alloy parts. The insert tool had a female thread and the Helicoil was screwed through this into the part and the tang broken off by turning the driver anti-clockwise.
Thanks for the interest, comment and anecdote Gerry. It seems that helicoils are used in more applications than just repairs and therefore supports other views regarding their strength. Cheers.
hope the extra 10lb/f helps 😀
Thanks Larry it most certainly should!
not so much so for the mechanicals but keep going on the ignition issues and for heavens sake,lets be contentious, do yourself a favour and ditch the Champions in favour of NGK or Bosch alternatives,you will be amazed.
Thanks Robert. Agree that is a contentious subject. There's so much conflicting information on the net and in the end it all seems to balance out to "fit what the factory fitted/recommended". Although I am a little biased as I do have a large stock of Champions .......