Does an A65 have a sludge trap?

[KiwiGF]

If so……might explain this absolute disaster for the (NZ) owner. The cost of repair will be eye watering.

I have spare cases for my A10 in case this ever happens to me (not great condition but usable) but not a spare barrel or crank.

[limeyrob]

Yes it does and yes it blocks up and causes things like that.  I bought an A65 new and the sludge trap blocked and seized the bottom end in 25,000 miles. It was rebuild-able and i got it done at the factory in the final weeks before they shut.  I fitted a cartridge filter and would strongly recommend anyone with an A65 does the same.  Its not unknown for the rod to punch though into the gear box and trash that too.
I would say 15 to 20,000 is the max mileage between sludge trap clean outs.

[Rex]

Expensive maybe, but dunno about "eye watering".
It was a mass-produced bike and many thousands were made, so the parts are relatively common plus they're easy to work on.
 The same damage on say, a Scott, Rudge or Vincent really would be eye watering.

[limeyrob]

Its the cost of the rebuild. A used engine will be cheap enough but then there's the boring, crank grind etc and the shells and pistons are getting a bit pricey.  Frustrating if the engine that blew was a good runner.

[JulianS]

The radial flywheel bolts can also fail due to fatigue. Happened on my A10. One bolt sheered off and punched out the bottom of the crankcase. Crank x ray checked and no other damage to it but cases totally written off.

[BagONails]

Very sad 

As someone who's an A10 owner and rebuilding a '67 A65 Spitfire currently I'm interested to know why a unit engine would sludge up quicker than a pre unit, the bottom ends appear very similar?

I have until now resisted the urge to fit a filter on my A10 as I figure on doing less than 2000 miles / year on it and I change the low detergent oil, clean the screens, scoop out the sludge in the oil/settling tank flush the lines and run a magnetic sump plug etc. once a year and I figured on doing the same with the A65 if it ever gets to the running stage!

Your thoughts/comments gentlemen?

[limeyrob]

Having done quite a bit of mileage on both A10s and a late A65, the A65 is a much higher revving engine and needs to be revved a lot more.  There's a noticeable kick at around 4000 revs and its enjoyable to keep the revs up.  That's a lot more centrifuging going on.  I found my A65 worked its oil hard, I had an oil pressure gauge and the pressure would drop alarmingly once the oil had a done a couple of thousand miles.  And compared to the A10 it did get very hot.  I had 10 1/2: 1 pistons and it ran really well but only straight 50 could survive the heat and loads.  I fitted the cartridge filter after the sludge trap blocked.
A 9:1 Lightning is 52 hp and with 10 1/2 :1, inlet stacks and free flowing exhaust I would say it was between 55 and 60 hp, that's a lot for a design that's mechanically very similar to an 30 hp A7.

[chaterlea25]

Hi All,
A few weeks ago I pulled an A65 crank apart, it had not been stripped since it had an SRM conversion 34 years ago . It is fitted with a return line oil filter and got very frequent oil changes, it ran on 20/50  oil.
The sludge trap plug looked odd and did not have a hex or slot, so I welded an allen bolt to it and removed with the impact gun..
The sludge trap was more than half full and the shell bearings were showing copper through the white metal in places so it was time for a refurb . The big end journals are still in spec so new shells and rod bolts will get it back on the road for the foreseeable future. The main bearings are fit for re use.
Attached photos include a couple of the tool I use to remove the sludge trap tube without damaging it
A 4in. long piece of 1/2in. threaded bar has a 1/4in hole drilled at right angles to it near one end, plus a 11/16 in long (or near) piece of 6 mm bolt or rod thats an easy fit in the 1/4 hole. Remove the radial flywheel bolt and enough of the sludge to insert the threaded bar into the sludge tube then poke the short piece down the bolt hole and into the cross hole in the 1/2 bar, tighten the nut and it will pull out the tube without damaging it
This tool also works on big journal A10's and Triumphs

John

[limeyrob]

That's very interesting and disappointing as it shows that the in-line filter is not keeping the sludge trap clear.  What millage had it done since the trap was cleaned?
I do wonder whether the sludge traps get to half full quite quickly then stay at that level for quite a long time as the oil flows across the surface and out the holes?  Wishful thinking perhaps?

[groily]

The filtration question is interesting. I was lucky with my A, which had a semi-clean sludge trap after about 30K miles in my hands, plus whatever the previous bloke had done (not much probably). That also had b/e journals within spec and a good t/s bush & journal, still at 1.5 thou clearance. It didn't have a return side after-market filter, also ran on 20/50 and was changed every 1000 miles. So I just fitted new shells, rod nuts etc and away she went and still does - at close to the same mileage again. It seldom did trips shorter than 20 miles, and mostly was run for a few hours, with stops, when taken out. I think that is one key to longevity, but whether it affects sludge build-up  particularly, rather than just condensation levels, bore wear and so on, I'm not sure.

By comparison, my AMC twins are fitted with a (primitive) feed-side filter system, involving a replaceable and cleanable felt / mesh item in a chamber across the crankcases just inboard of the (separate) supply-side oil pump. That filter comes out for a good clean every oil change, or every other at worst. There is always some small amount of debris embedded in the felt - tiny bits of aluminium, other specks of whatever. If I added all that up over, say, 30 oil changes, it would probably be 'quite a lot' although the amount inevitably decreases after the first few thousand miles following a rebuild. Were the debris NOT in the filter, it would presumably find somewhere else to park itself - in the oilways or the tank. Those cranks have screwed-in c/sunk 0BA plugs to allow access for cleaning the oil passages (but no trap as such) and a clean-out is naturally a 'should do' when things are apart.

However, I haven't ever seen enough to worry about in any of the cranks I've run with. One of the engines has done several hundred thousand miles now and still does a few thousand every year. Some of the real experts with these things reckon on 60K miles between bottom end rebuilds, although I have usually pulled them down as a preventative at about 40K in an effort to preserve the cranks, which, like A10 ones, don't exactly grow on trees.

I therefore wonder whether the ultimate answer to cleanliness and long life would lie in having a proper pressure-side filter system. The AMC one is, as I say, primitive, but better than nothing. There was a marque specialist who redesigned the supply side of his and some other folks' AMC twin engines to allow the incorporation of modern cartridge filters on the feed side via external plumbing and crankcase mods, but it was complicated. Was it, would it be, could it be, worth it, even if it were possible? Could a Beesa pump handle it? And would it reduce the sludge thing anyway?
Dunno at all, but it's something more interesting to ponder of a shite wet morning than the state of the nation  . . .

[Triton Thrasher]

Was it, would it be, could it be, worth it, even if it were possible? Could a Beesa pump handle it? And would it reduce the sludge thing anyway?  . . .

A filter between the pump and the pressure relief valve is good in principle, but it’s just too complicated on most old Brits.  You’ll end up with a net reduction in reliability: too many high pressure hot oil leak opportunities.

[groily]

too many high pressure hot oil leak opportunities.

That is so very true TT. There are some quite good techniques for sealing the crankcase joint where the pressure-side filter passes across on AMCs - but it's work, and a pita to fix if it leaks. About the same pita as replacing the ball and spring on a pre-unit A to reduce wet-sumping.
With cold oil you're looking at up to 140psi they say (the prv goes off at way less obviously but the joint still has to be spot-on.)
The filter's presence may be why those cranks stay reasonably clean I suppose, although it might also be partly because the b/end supply is a powerful squirt going a very direct, short and equal distance to each side from the slightly-unfairly-infamous third main plain bearing. Which avoids any of the timing side bush palaver, or the need for end-fed quills, along with any concern about reduced flow or pressure on one side, while also allowing the use of generous roller mains because c/shaft float is controlled by car-style thrust washers in the middle. (Shame the execution wasn't always as good as the bare bones of the concept though!)
Oh well, sun's out now, time to trundle down to the boulangerie for some fresh bread on the old LE Velo  . . . .

[chaterlea25]

Hi All,
Rob,
We were trying to estimate the mileage the A65 had done in those 34 years
For the first number of years it was the owners sole mode of transport around London, then he came home to Ireland and the yearly mileage went down somewhat
He still uses the bike to travel all over Ireland on a regular basis,
Estimated mileage is 40-50 k miles
The top end of the engine is well worn out
Compression was down so much you could easily push the kickstart down by hand, a blown head gasket prompted the stip down.
The bores were on plus 60 so need sleeping or fitting the Devimead 650 cylinder I have, then either rebuild the head or fit the one that came with the Devimead cylinder which only had a few hundred miles on before the crank broke, (c 1990

John)

[Triton Thrasher]

That is so very true TT. There are some quite good techniques for sealing the crankcase joint where the pressure-side filter passes across on AMCs - but it's work, and a pita to fix if it leaks. About the same pita as replacing the ball and spring on a pre-unit A to reduce wet-sumping.
With cold oil you're looking at up to 140psi they say (the prv goes off at way less obviously but the joint still has to be spot-on.)
The filter's presence may be why those cranks stay reasonably clean I suppose, although it might also be partly because the b/end supply is a powerful squirt going a very direct, short and equal distance to each side from the slightly-unfairly-infamous third main plain bearing. Which avoids any of the timing side bush palaver, or the need for end-fed quills, along with any concern about reduced flow or pressure on one side, while also allowing the use of generous roller mains because c/shaft float is controlled by car-style thrust washers in the middle. (Shame the execution wasn't always as good as the bare bones of the concept though!)
Oh well, sun's out now, time to trundle down to the boulangerie for some fresh bread on the old LE Velo  . . . .

Feed side filtering should be designed into the engine, as in practically all cars.  I don’t know much about the AMC twins, but it’s disappointing to hear that they didn’t make the high pressure oil route foolproof.

I was thinking of a conversion that is or was available for Tr****h twins, that led oil out through the side of the timing cover, to a filter in front of the engine, thence to the end feed gallery.  It looked vulnerable.

Edit: Google tells me it’s available and the filter is behind the Unit gearbox.

[groily]

Feed side filtering should be designed into the engine, as in practically all cars.  I don’t know much about the AMC twins, but it’s disappointing to hear that they didn’t make the high pressure oil route foolproof.
I was thinking of a conversion that is or was available for Tr****h twins, that led oil out through the side of the timing cover, to a filter in front of the engine, thence to the end feed gallery.  It looked vulnerable.

Not 100% foolproof TT, no - but not so bad for late 1940s I guess, and definitely a good idea in theory. That said, a felt or mesh job is never going to be good compared to a modern cartridge at picking stuff up, although it's better than nowt. There are in fact fairly generous mating surfaces on the AMC cases in the critical area, and most people do manage to keep things oil tight there - it's just a big pain in those relatively few cases where the joint does leak, generally but not always due to poor assembly.
The modern filter adaptation on them doesn't look TOO bad, see pic - but the machining work to create the filter base and the internal drillings to get the 'ins' and 'outs' to line up with the rest of the oil system is very nadgery (and way beyond my pay grade). There are drawings available on the website of the owners' club but just looking at them makes me feel queasy. As with all our obsessions though, there are folk with the skill and the patience to do amazing things (whether they're needed or not!).