Yes Allan exactly as the one I'm looking at same spaces. That says to me it seems ok, GOOD!!!
Thanks

I have put some A70 engine pix in my Google Drive. Click HERE to request access.

There are no full pictures of the crankshaft. I will add those.. as soon as I find them!

Thanks Ray I have downloaded them for reference in the future.
When you find more please let me know

Indeed they were fitted to late A65s. I bought a '72 lower end about a year ago & it had the steel capped rods. I thought I had an A70 crank for a brief moment.

I just uploaded some crankshaft pictures that compare a '72 A65 to the A70 crank. These give the idea of the differences in flywheels & bush size.. There are pix of an A65 bush on both cranks. The difference is noticeable in spite of the poor lighting. Apologies for the dim pix. I'm not in a position to retake them!

Many thanks Ray. I will add them to the portfolio if that is ok?

Go for it Allan!

A question to you with A70 experience,
A65 has a 3/4" sludge trap plug but the A70 seems to have a ⅝" plug which is about 3mm less in dia for us metric.

Can anyone show a photo of a A70 sludge trap tube? or best both a A70 and a A65 so one can compare.

I wonder if the A70 sludge trap tube holds less or same amount of sludge before it gets full???
the attached image is A65 and the A70 must be less diameter cause of plug is smaller but is the long part same diameter?

If the A70 is less in diameter how many miles less should one ride before cleaning is a must? I know its a hypothetic question..

Pictures please

Fit an oil filter in the return, then question will not need an answer, which will be guesses anyway.

Hi Kommando,
the bike have 15000 miles at least since last cleaning and I think it has run with non detergent oil so I believe it must have quiet lot of sludge.
putting a filter will it help under those circumstances? will it not just build up more..

Whatever is there will be added to very slowly once the filter is in place as long as you use a detergent oil, the original plan was for the trap to be close to being filled as your engine needed a rebuild so you were not expected to clean the trap between rebuilds.

I have looked everywhere for info regarding the maximum miles before sludge and other bottom end service interval (how many miles) but failed to find it.
I also wonder if its different from a65 with a smaller sludge tube.

The thing if it has 15000 miles on non detergent with loads of sludge and suddenly you use detergent and filter would it not start slowly to drag sludge thru the bid ends? I mean the detergent would start to lose up the sludge?

Many thanks Ray

I concur, I used to run mineral oil and when I stripped the motor down only a few thousand later I found that there was some soft sludge inside the trap. Not like the hard compacted sludge you normally find but some all the same. This was with an oil filter also.

The trap was removed, crank cleaned and when checked again after a similar distance there was nothing to speak of in there.
I’ve used modern bike oils since and now use Ester based oil.

As for sludge being loosened, I don’t know but as any deposits are centrifugally flung to the outside of the trap, I can see it doing very little to the sludge already in there. Although that’s only My assumption.

There’s nothing to stop you stripping the motor down, check all the specs, clean and rebuild feeling quite happy that it will all be ok.
Or run the bike, keep the oil changed and see how long it lasts, if it was well looked after before in its life then it might go for a very long time.

If it was me I’d strip it down but there are many a bike on the road that’s been bought and ran with no problems at all.

Allan, you are a wise fella.. I have ridden singles for 35 years and very little twins and not worked on any engine twin since 1983 which was a T120R.
Never a BSA twin. That and the fact that A70 parts are so hard to find I fear its a fair chance the rebuild will stall.. This is why I need to discuss it.
And while having it down I probably would remove the triumph pistons and add proper A70 pistons but then I would need to replace new liners or have another STD cylinder. so you see I create my own little problems..

That sludge in the trap is normally rock solid, the one and only time I have seen it been disturbed was a B44 crank that was shipped for the US to the UK by ship, the crank was dry and a few grains worked loose making the big end feel notchy. Cleaned out the sludge trap which was the normal concrete.

The sludge trap plug is smaller. Mine was badly mangled. I spent an hour dressing it up for reuse when I discovered that britishonly.com has them.

The part number is 71-2682.It's one of the few A70 specific parts that is available!

I think as long as you don't loose your thrust washer that you should be ok for a rebuild.

Ray BO list them as 1/2" x18tpi but I heard they should be 5/8 x 18tpi
what size is yours ?

You would be pretty unlucky to have a busted sludge trap tube.

I think its unlikely that the bike has used a non-detergent oil for its entire life, especially when you consider that the oil recommended by BSA in 1971 would have been a 20W50 or similar oil with an API grade of SC or above. These would have been oils with some detergent content so any sludge and debris would have been dispersed in the oil. Perhaps later in its life someone used a non detergent monograde and this should result in any sludge ending up in the sump.

Since the OIF A65 had no oil filter, using a detergent oil should cause any oil contamination to settle in the frame reservoir and the sludge trap. You could perhaps try and check for sludge in the frame but its going to be tricky as there is no access, maybe a borescope could be used?

The only real answer is to check the sludge trap, but that means major work unfortunately.

Does anyone know what an A70 sludge trap tube looks like?
I've recently managed to find an A70 crank less flywheel, having previously modified an A10 crank to fit my A70, but the tube appears to be firmly stuck in the hole. At first I didn't think there was one fitted until someone mentioned that the hole dia is 5/8", whereas mine is only 9/16" and I can just see the edge of a very thin wall tube. I can see it being a pig to remove without destroying it due to it being fitted in a blind hole.

The sludge tube should have a hole near the end which is used for hooking the tube out of the crankshaft, as well as being the main oil feed. If that's chewed up, it's also possible to wriggle a mechanic's hook or bent pick down the tube to hook the locating hole that the end of the flywheel bolt runs into.

Hi Servodyne,
I am not familiar with the A70 but can I ask, is the tube held in place by one of the flywheel bolts?
I made up a puller to remove Triumph tubes from a length of 1/2in, threaded rod
It is cross drilled near one end maybe 1/4in. dia.
Some measuring down the flywheel bolt hole to find the length of a pin that would fit down the bolt hole through the sludge tube
and the threaded rod, but not long enough to catch on the crank itself
Adding a thick flat washer and nut to the rod outer end, tightening the nut pulled the tube out without damaging the tube

John

Thanks for the replies.
I have tried using a hooked wire in the flywheel bolt locating hole but it doesn't want to budge and I can't use a threaded rod as a puller because you can only get to one side of the tube because it's fitted into a blind hole. There isn't a hole near the end, just the holes coming from the four big end feeds and the locating hole from the flywheel bolt.
The trouble is I'm not convinced it's a tube at all. I could be just a step where the bore goes from 5/8" to 9/16". That's why I would like to see what a sludge tube looks like before I get medieval with trying to remove it.

Jim

Find a taper thread tap that screws/ fits in the sludge trap, run a nut down the tap with a small collar for the trap to pull into. Crank on the nut, it should pull free. Obviously the tap will mark the trap inner , that wont affect its performance.

Morgan - the plug is 5/8. I uploaded a picture comparing it to an A65 plug. The difference is significant. I really don't know why it's so much smaller except that perhaps they wanted to keep more metal in the web as the journal is closer to the end of the throw. I'm a programmer not an engineer so I really have no idea, just speculating.

My Proto 1/2" driver screwdriver bit that I use for this purpose required some grinding before it would fit. The plug was a mess. I tried dressing it up a bit but the effort was useless. Luckily I found one (& bought 2).