Monday, 29 December 2014

More on Oil

So today, we have something like 6 degrees Celsius outside. I've just completed about 3 miles around town and I have measured the oil temperature using a meat thermometer (not the one that was stuck in the Christmas turkey last week), and we have 73 degrees Celsius.

Please don't stick it in the Turkey
If you use one of these though, you will need to stop the engine first. The RF interference driven by the HT cables is phenomenal and stops the thermometer working at all. I guess the thermocouple wires pick up the RF.

Now, looking at the oil data sheets, we can see that the kinematic viscosities are similar at 100 degrees Celsius. Plotted they look like this:

This gives us a clue, but we can't get too excited because there are only two data points per grade. The temperature/viscosity relationship is not linear. Look at this, plotted on a logarithmic scale:

This gives us a better picture. Notice that the viscosity of the SAE 50 is about 20 cst at 100 degrees C, which agrees with the data in  the first chart, but that at 75 degrees C the viscosity is about 40 cst. That should give us about a bit more oil pressure for the same temperature than the 20/50W we are using now.

Friday, 26 December 2014

Oil & Oil Pressure

So this is one of those posts that we use to collect thoughts.

Amelia has done about 25 miles, and has had her head torqued down and the oil pressure relief valve spring replaced. She is running in on Tetrosyl 20w/50 multigrade oil, to API SE spec. When cold, the oil pressure gauge shows about 55-60 psi at idle speeds; after a 6 mile run around town, at speeds up to 25 mph or so, the oil pressure drops to almost zero at idle.

Darcy's Law tells us that flow through an orifice is proportional to the area of the orifice, the pressure drop across the orifice and the viscosity of the fluid.

The viscosity of the 20w/50 will be something like 18 centistokes at 100°C, rising to something like 135 cst at 40°C. After the run, the oil was visibly very free flowing and hot.

The relief valve may be controlling the pressure at idle - it may prevent the pressure exceeding 55-60 psi, but if this is the case it will have no effect at higher temperatures unless it is stuck open which seems unlikely given that the pressure displayed on the gauge falls gradually as the temperature rises.

Additionally, the effect is repeatable - the cold idle oil pressure is always 55-60 psi, and it always drops to near zero when it is hot, so I do not think we are seeing mechanical changes in the relief valve or the engine clearances - yet.

The Morgo is a gear pump which requires clearances between its gears to operate, and these clearances will allow more fluid to slip ineffectively around the gears when the viscosity is low. Are we right to fit gear pumps when the engine runs so hot?

And then there is the gauge. Ariel indicate that these engines should run at about 40-45 psi on SAE 50, so my gauge readings are not unreasonable, but we don't really know how accurate the gauge is or even if its accuracy is linear.

But one thing is clear - when the oil is hot (and we don't yet know how hot it really is) the loss in viscosity is such that the pump can push its full flow capacity (which itself may be compromised by low viscosity) around the engine without creating any pressure in the system.

And pressure is needed to prevent the bearing surfaces coming into contact with each other.

Wednesday, 3 December 2014

Oil... everywhere

So a few days later and I run the engine with the front main bearing cap off. I'm not going to show you a picture, because there would be oil everywhere, but you can see from this shot with the cap loose that there is oil there; with it off it gushes out:

And here we have a new spring just arrived from Draganfly, about 25% longer and somewhat stiffer than the old one:

And here we have an oil pressure gauge showing a previously unreached figure, 55 psig, at tickover - engine relatively cold (about 5 minutes running). Thats more than 50% up on last time.

So now we need a road test. Yippee!

Saturday, 29 November 2014

Another Four Miles

Well, I have had the timing cover off and the pump is solid, so I have stripped the relief valve to reseat it. Oil pressure after a four mile run today is much the same, as we await the new spring.

Still, she's running a treat and she looks lovely!

So to get my head around engineering behind the oil pressure regulator I need to confirm what size the ball seat is, i.e. the diameter of the oilway in the offside end of the front crank. The ball is 3/16", so the seat must be maybe 5/32"? I'm trying to understand what the spring rate would need to be for a given back pressure in the system.

For example, a 5/32" seat would give an area of 0.019 sq in. exposed to pressure, so a 1 lb spring would give me about 50 psi. My existing spring is not that heavy (its the original one, new one on the way) and, surprise surprise, does not achieve 50 psi on the gauge - thats assuming the valve is ever opened!

I plan to have a look and see if the regulator valve is used next time I run the engine, and I will have to find a way of calibrating the pressure gauge..

Monday, 24 November 2014

Latest trip

Well, a bit more news today, and a four mile trip around town. 

The fuel filter has gone back in the spares box to be replaced by a plain pipe and a gauze strainer in the carburettor banjo - all air locks now banished to the spares box along with the fuel filter. Apart from a very fast tickover, all seems well in the fuel department.

I've been looking at more loose ends. I had meant to look at the chain oiler screw in the primary case for a while, since the thread in the primary chain case was refusing to allow the oiler screw to pass through it. I measured it, found it was 2 BA and cleaned it out only to realise that the screw I had was just an old carburetter mixture screw and was way too short. This is what it is supposed to look like:

Thanks to Steve Clarke for this picture.

The clutch has seen some adjustment and a much better cleanup job on the splines. It's dragging a little, but a vast improvement over what I had. Changes whilst riding are noiseless - engaging first at a standstill is still noisy but much less so. By the time I had got back it seemed to have loosened up and needed adjusting again.

The electrics are all behaving themselves; the handling is also fine but as I have discovered before I need to keep an eye on the tyre pressures - 28 in the front and 24 in the rear seems to be about right, and the consensus of opinion canvassed on the splendid AOMCC forum.

I've re-torqued the head, as regular blog readers will know. Cold, the oil pressure is about 35 psi - but this dropped to about 10 psi with the engine hot, so do we think the relief valve could be due for a new spring? AOMCC wisdom suggests that the Morgo pump may have loosened off (thanks Mark) so we will have to have a look at that before the next trip. I will get a new spring for the relief valve as well. It's getting properly hot now, but the engine is quiet and I have no exhaust or oil leaks.

Looking forward to the next trip!

Sunday, 16 November 2014

Settling Down

Time for some maintenance - re torque the head. There are a few small oil leaks around the head gasket, so I pull the nuts down a little more, maybe a 1/4 turn on each - except these guys:

These guys are only hand tight. Now I know I made a better job of that when i pulled them down the first time...

So I've worked around the head and the base gasket, pulling everything down. I've also replaced the rocker cover studs, one of which was badly stripped (at the nut, not the head, fortunately!).

So I've also had to reset the tappets, and since all the plugs were out I have bent the terminals a little to improve the HT cable routing.

I've sealed the exhausts at the cylinder head with high temperature silicone sealant, so hopefully we won't have any more exhaust or oil leaks.

Next stop was the clutch, which I have readjusted.

The final job today was to take out the inline fuel filter which served only to cause air locks. You have to be careful with these - there does not seem to be much resistance to flow but really they are better suited to pressurised fuel systems.

So that's it. She starts beautifully, coming off the bi-starter after a few minutes and settles at about 25 psi oil pressure at idle, which I am very happy with.

Just running it on the stand, the clutch seems better but it will take a road test to check that out. Since there is builder-mess outside the workshop door and my back is now aching again, we will leave it for today.

Saturday, 4 October 2014

Little steps

Well, its been 2 months since my last post, and you might be forgiven for thinking that nothing much was going on.

Soon after getting the bike started as I showed you in a previous post, the registration came through and I was able to order the number plates. 

There were a few little jobs left to do after start up, which got easier every time I tried it. I'd noticed when building the engine up that one of the rocker cover studs was damaged, not allowing the cover to be tightened down. I replaced them all with new studs from Drags. 

I made a spacer for the primary case to frame bolt, and filled the primary chain case up to the drain hole. This appeared to be necessary to get the oil level sufficiently high to lubricate the chain, but AOMCC wisdom suggests I may regret that later.

When I'm out for the first time on a newly rebuilt bike, I plan a route, around the house or workshop, not more than pushing distance away. That way, I can ride round and round and never be too far to push the bike home. When I've gained some confidence, I increase the radius – the idea being that I shake out the larger issues near home, and then if something happens when I am farther away I still only have the radius of the circular route to cover to safety.

Braving the mid-morning traffic on the first outing, the fuel line airlock returned just as I was passing a crowded pub... All the faces turned to listen to the old bike thundering down a shallow hill just as it spluttered to a halt before attempting the other side.

I pushed it down a side road and home, to arrive, in time honoured fashion, drenched in sweat...

Riding impressions? Initially I found the steering wandering, which was easily cured by backing off the steering damper. Its incredibly smooth – with a surge of torque as you open up. I didn't get out of second gear on the first few trips. Its easy to start, and every time I do it, I notice the engine's stiffness easing up. 

The fuel system is still plagued by air locks. Its not help by me filling the tank with barely a gallon – the tap is very high in the tank, especially since the tank mounting rubbers are not correct resulting in the rear of the tank being rather high.

The mixture needed setting up, as did the tickover, which resulted in me finding out that adjusting the carburetter with the engine running is a risky operation if you don't want to burn your hands. I made some special screwdrivers to get at oddly position screws.

The brakes are being adjusted on every trip, and they are still bedding in.

It seems to be charging happily - in fact the electricals are all ok.

Tuesday, 26 August 2014

Happy Day!

Well... What a day!

As you know, I had run up the oil pressure on the power drill, and everything was connected so there wasn't really any excuse not to try and light her up. Initially I had a few issues getting the fuel into the carburettor, some sort of air lock, but once that was sorted, away she went!

YouTube video: Amelia Awakened 
YouTube video: Amelia's Oil Pressure 

And doesn't she look great with her exhaust wrappings off!

Thanks to everyone that's provided help, encouragement and bits over the last three years.

Friday, 22 August 2014

Oil Pressure

So as I have mentioned previously, my plan was to spin the engine up on the big power drill. I've now done this using a 1/2" square driver with a hexagonal shank in the drill chuck, with the drill set to 2nd gear - slow speed, high torque. The drill drives the engine through the crankshaft nut under the oil pump.

I connected a short hose to trap any fluids coming out of the oil pressure gauge line and take them back to the oil tank. Because of course the timing cover is off, there is a lot of oil in the drip tray which comes from the rear main bearing. 

The plugs are out to reduce the torque required from the drill.

And here it is:

Evidence of oil emerging from the return line. When the drill is running, you can see this pouring out, and you can see it at all eight rockers as well. Its noticeable that the inlet rockers get a lot more oil than the exhaust rockers - Ariel should have adjusted the size of the oil holes (smaller in the inlet rockers) to increase the feed to the exhaust rockers.

After a few minutes on the power drill, the bike is noticeably easier to kick over. Next I refitted the rocker cover studs and I put the tank and the oil pressure gauge back on and ran the test again looking for measurable oil pressure.

At maybe 250 rpm on the drill I am getting something like 25 psi.

Thursday, 14 August 2014

Oil Pressure Gauge

So the electrics are done and the oil system is next. As you can see from this pic, there is a lot of paint in the oil pressure gauge hole:

Easily sorted with a flap wheel in a hand drill (very very low speed)


Oil pressure gauge lines:

What's left?

Lots of bits and bobs left to do, but at least the electrics are done. No pictures, but after blowing a couple of fuses due to an ignition circuit fault in the ammeter panel, and some poor connections to old bulbs, I have a fully functioning electrical system. Only a few items left:

  • a link between the brake pedal and the brake lamp switch
  • the speedometer bulb is not working
  • the dynamo is untested
  • the regulator is not connected at the battery

It's mainly oil system now. The sump plate went on last night:

Its a new one with a drain plug, from Drags. Oil filter and oil pressure gauge next.

Tuesday, 12 August 2014

Modifications - Indicators

I've decided to fit Amelia with indicators, in deference to modern traffic conditions. They are typical Lucas look-alikes, and don't look too out of place.

Front indicators retain the headlights

These little tabs are cut from 3 mm thick sheet. They have 3/8" UNF nuts welded to them to suit the indicator stalks:

They weld to the rear mudguard stays:

For wiring up, I am using these 'Japanese Bullets' - small crimp on connectors, fully weather proof.

1.0 mm2 three core is useful for indicators. I like to make an entirely separate loom for the indicators, so that they can be removed easily if another owner wishes to do that:

Put a dedicated earth wire into the shell and attach it to the bulb holder with a ring terminal. By design, the earth path on these repro indicators goes through the plating... Nasty...

So, what you can do is bring an earth wire down the indicator stem to a dedicated earth wire. The earth wire can connect to one of the bulb holder mounting screws. Normally I don't use these modern terminals, but no-one will ever see this:

The handlebar switch is available as a generic indicator switch from many Brit bike outlets. It has three wires: a common yellow wire from the flasher unit, and red and green wires for right & left:

All the wires come into the headlamp where the red & green wires are terminated with a Y connector: one path to the front indicator, the other into the loom heading to the rear. The yellow wire connects to the flasher, which sits in the headlamp shell, protected by a rubber sleeve - MZ style!

The flasher is supplied from a dedicated fuse

Saturday, 2 August 2014


Time to make up some fuel lines. I've got 14" of 1/4" ethanol resistant fuel lines knocking around, and some suitable crimp ferrules.

To make a good crimp, you need a little tool which you can buy or, with a bit of 1/2" square barstock you can make your own. The tool is just two 2" lengths of 1/2" square bar, clamped together and drilled for a 1/2" hole, such that there is a semicircle in each bar. V shaped grooves have been filed at four positions around the outside of the hole, and two short 1/4" rods set into the two halves of the tool maintain alignment.

Cut the end of the fuel line square with a sharp blade. Slip the ferrule over the end and push the banjo, tee, or hose tail (with the union nut in place) into the hose, as far as it goes. The fuel line, normally 1/2" OD, will swell out to something like 17/32".

Place the two halves of the tool around the ferrule and squeeze in the vice. The ferrule compresses the tube back to about 15/32", thus retaining it on the hose tail. It produces a better crimp if you squeeze it half way, and then rotate the ferrule/hose assembly 90 degrees in the tool, then finish the crimp.

Compressing the ferrule to less than its original diameter generates some 'spare' material, which swages out into the V grooves we cut. Here is the fuel tap end:

Here is the carburettor banjo:

And here is the non-standard 1/4" fuel filter. Judging by the cr@p I get out of my Bantam tank we will need this:

Monday, 28 July 2014

Dynamo & Split Bullets

Time to hook up the dynamo. The split bullets so beloved of Mr Lucas are a crude but effective design. I thought I'd show you how to use them.

Strip the cable insulation so that there is a similar length of bare wire as the length of the bullet:

Push the wire into the wider end of the bullet, and fan the wire evenly over the bullet:

You may need to pass one of the wires through the Tufnol retaining piece before you fit the bullet. Push both the bullets into their socket in the dynamo and screw the retaining piece in place firmly. You will see the bullets slide into their slots:

Then you are done. Fit the dynamo end cover, making sure you don't trap the flexible brush wires in it, and screw the cap down:

Loose Ends

Well, its been an active and enjoyable weekend tidying up loose ends. Thanks go to Patrick Huthwaite who came by yesterday to do the inspection for the Dating Certificate - nice to meet you Sir.

On with the oil tank - the secret to fitting it, is to get it inboard enough to allow the clearance built in the top of the tank to accommodate the frame tube; the secret to allowing this to happen is to remove the nut on the gearbox top bolt.

Next problem is getting the oil lines in. I've realised that most of the struggle I have with this is down to the fact that the strainer I made is way too long, with the result that you have to bend it to get it in and it always catches on the threaded boss in the tank. I cut it down and re-soldered it:

So now, the oil lines go in easily.

I've also fixed the rocker feed oil lines:

And the rocker shafts are sealed:

What else?

Sunday, 27 July 2014

O Lucky Man

Well, there are advantages to being a bit of an eBay vulture...

Gauge, oil line, solder nipple and union nut
My latest purchase is this original Ariel oil pressure gauge, of exactly the right type for the Square Four. This is connected into the double oil line above the cylinder head with a short pipe that comes down through a tube welded into the fuel tank.

You can just see it in the top of this picture. The short line is made from parts from Draganfly - 17" of 1/8" copper tube, two 1/8" solder nipples and appropriate 1/8" BSPP union nuts. You can see the conical nose to the nipple, and the conical seat in the gauge - together these form a metal to metal seal. The nipple is soft soldered to the tube using Baker's Fluid, lead solder and a small blow torch.

That 2 BA stud on the back of the gauge passes through a welded bracket in the petrol tank.

Saturday, 26 July 2014

Slippin' and slidin'

Moving swiftly on...

Not a huge amount to report today, but the gearbox is now filled with a 50/50 mix of Castrol LM grease and 20W/50 engine oil.

Access to the gearbox filler entails removal of the oil tank, which I don't have the knack for yet. The oil tank is very tight to the frame tube, can't be tilted forward because of the distributor and the frame seat tube, can't be tilted back because of the toolbox and the mudguard and is generally a pain...

However, the gearbox is now filled with about 450 ml of oil/grease mix and the oil lines have their hose clips in place - modern ones unfortunately.

Tomorrow we will have a major step forward - we are having a visit from a local AOMCC member, Patrick Huthwaite, whose inspection is the next step in the registration process.

Hopefully it won't rain.

Thursday, 24 July 2014

Mighty Morgo

Today I fitted the Morgo oil pump made by Autovalues Engineering from Bradford.

The Morgo is a gear type pump, and is very nicely manufactured, well packed and is provided with a comprehensive set of instructions. While there are several Morgo rotary pumps for other Ariels & Triumphs, the fitting kits and instructions are bespoke to the model you are fitting. Very nice quality, well thought out.

The pump comes with a fitting kit, consisting of the left hand drive nut, a set of shims, a gasket, two tab washers and two mounting bolts

This is the drive side of the pump, showing the Oldham coupling used to drive the pump from the camshaft.

And here is the drive nut for the pump. Those slots are closely toleranced to prevent rattles and wear

Here it is in place. I've got it fitted with the original studs at the moment, since I don't like the idea of wearing threads in the soft crankcase to remove a service item but in practice you have to engage the pump coupling before bolting up - it is close fitting in its slots, as it needs to be, and this makes the bolts supplied with the pump the only practical way of fitting it.

I need to prime the pump - so I will refit it with the bolts supplied with the pump.