W/NG - Cleaning the fuel tap

 One embarrassing thing that happened last year was a shortage of fuel - or rather not. I ran out of fuel out in the wilds of Norfolk having given son Thomas a lecture about coming out without checking the tank, discovering a little while later that not only had I run out of fuel but that the reserve tap wasn't working.

Emptying the tank, I pulled the tap off to check and found the filter torn and the reserve port full of paint chips:

A few minutes poking around soon had that clear, and I fitted a new filter:

I realised later that this one is of a coarser mesh than I would have liked - I'll have to replace it again...

FH fuel tap

The Owner's Manual for the FH describes, in several paragraphs, how to operate the fuel tap and makes it very clear that the tap specified was not the usual two-plunger tap used by Ariel since before the war. In fact the manual tells you to pull the plunger to turn on the main supply, and then to twist and pull it again to get reserve. It took me a few eBay mistakes before I found the right one, courtesy of John Mitchell of the AOMCC. 

The tap John sold me was in great shape, but it was missing the filter and the main supply pipe which draws the main supply from a point above the water in the bottom of the ethanol-laden fuel. Since I have other taps with this pipe, and I have made several filters, it was no problem to make the missing parts.

I started with a bit of 3/16" copper tube which I annealed with the wonderful Rothenburg Superfire torch. I set the tube up in my cable nipple swage:

Using a centre punch & a pin punch, I belled out the tube until it was a tight fit in the register machined in the tap.

Next step was to make a little cylinder on the lathe to position the pipe within the filter. This is machined internally to fit the tube and externally to the same diameter as the filter, and soldered in place at the top end of the tube:

So there we have it, the components of the tap:

To assemble the tap, I pushed the swaged end of the tube into the register machined in the tap body - I didn't attempt to solder it in. I then pushed the tube into the filter, and applied some flux to the tap body where the filter sits and around the cylinder I made earlier, through the filter gauze.

When soldering the filter onto the tap body, you need a fair bit of heat - I use my kitchen blowtorch for those sort of jobs.

You'll notice the tap has a fibre washer - I usually use Dowty washers in this application, but there was no way the plunger was going to 'fall easily to hand' with a Dowty washer on the tap - so a thinner fibre washer it had to be.

Charlie's Shed - Petrol Tap Filters

Updated from December 2017

Many of the fuel tanks we have on our bikes are not in the best of condition and may be flaking rust or paint from inside, or worse, your tank liner may be in the process of falling to pieces. It's essential to have a good fuel filter.

Here are a few I made earlier:

Most of the fuel taps I have acquired have had either missing or holed filters, and, having had very limited success with the inline filters on the market (poor fuel resistance in plastics leading to cracking & cloudiness, or a ridiculous flow coefficient leading to fuel starvation) I have set about replacing the missing in-tank filters. This is typical of the damage you will find, if not a lot worse:

These are pretty simple to make if you are reasonably adept with a soldering iron. Start by removing the old one. I use a kitchen-type blow torch for this, which is plenty hot enough for sweating soft solder:

Hold the intake tube with a pair of pliers and twist it gently when the body is warm. It should come free quite easily

Look for the finest mesh you can find. The originals are a very fine copper mesh which is easy to obtain (though the mesh in the pictures is actually brass). Cut a suitable rectangle with scissors.

Start to form the cylindrical shape around a pencil.

You'll see that the final size for the filter on this double-plunger Ariel tap is very close to the diameter of an AAA battery:

I use a chamfered edge on an old credit card to form a tiny lap joint on both edges of the gauze, like I did with the oil strainer on the SQ4:

I then roll them around, mating up the lap joint and folding it down tight on the AAA former.

You can make a simpler lap joint like this:

Solder the joint with a small iron:

Flare the end to fit into the recess on top of the tap:

Have a good look at the recess on top of the tap. Make sure you clean out the joint of all goop, old fuel, rust and old solder. We are going to tin this area and sweat the new filter in.

Put the main feed pipe back in and trial fit the filter:

Now, push your AAA battery former up to the other end of the filter and form the closure:

Lay some solder onto the flare:

Lay a little more solder onto the end closure:

Flux the top of the tap and using a small blowtorch (the type you might use in the kitchen) apply some solder all around the joint, without the filter in place. Let it cool and clean it up and have a good look to see that it has run all the way around, then add the filter. Reheat the tap just sufficiently to melt the solder , and the heat should transfer to the solder ring around the filter flare allowing the two to fuse.

You might notice that this tap is fitted with a 3/8" BSP Dowty seal - makes a better job of sealing that joint than a fibre washer.

If you still have problems with your tap, check my post on replacing plungers here.

Thanks for reading, and I hope you found it useful.

Oops

Well, I got out on my test drive, and it feels much happier - smoother, more torque at the bottom end...

Unfortunately, about 5 miles in, a misfire appeared and the engine stopped. Having experienced this many times during the fuel filter saga, I was quick to look for fuel supply problems and cracked the fuel supply banjo to find all was well. The bike started again, only to stop again after about 100 yards - this happened once more, and then I was close enough to push it home...

Charging had looked good on the ammeter from the first day. All the lights worked perfectly, apart from one indicator which persistently rotated around to face the floor, but in general everything had been fine. However today, when I had the bike running again, switching on the lights would kill the engine.

The Lucas C35SD gives 70 W at about 1700 rpm which equates to 32 mph in top gear, but when you are running around town the ignition, brake light and frequently used indicator loads soon drain the battery, which appears as a fuel-starvation-like misfire. I cursed that fuel line again until I realised what was going on, and a CTEK battery charger came to my rescue. Actually you need about 20 W for the ignition alone, or about 3 Amps; in top gear, you get 3 Amps from the generator at an average of 23 mph – these bikes are really not for town use.

My 1951 Mk1 has a 20 Ah battery bank hidden in the Lucas GU11E style fibreglass box. I'd be surprised if you could even get to the shops with the earlier small battery...

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!

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.

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 positioned 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.

Crimps

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: