Feb 252015

The installation of the fuel tank had taken a number of fitting attempts and required the enlargement of one of the mounting holes. The toing and froing had inevitably resulted in a couple of light scratches inside the boot space. So I decided to remove the tank for a final time to paint the exposed metal in the mounting hole and touch up the scratches.

The tank was completely wrapped in sheets before extracting it to avoid further scratches. As it was being lifted clear the sheet snared on the corner of the flange for the boot boards, stopping the tank in its tracks and putting me off balance …. the tank came down on the rear wheel arch!

Even though it was the lightest of landings, the weight of the tank was sufficient to put a dent in the wheel arch. It was less than a 1cm long but, as its on a double curved surface, it stood out like a sore thumb. Absolutely gutted!

Even though it’s a small dent, your eye is drawn to it The irony of it all: it’s hard to photograph!

The only saving grace was the sheet had offered some protection and the paint wasn’t damaged. I’d seen companies offering a paintless dent removal service. It had to be worth a go so I contacted a guy operating under the name Dr Dent.

His toolkit appeared to consist of a vast number of levers in all shapes and sizes which are used to press out dents from behind. A couple of minutes later (most of which was spent chatting!) and he was out with the polisher – job done! Even right up close, I can’t find where it was dented. Needless to say I would thoroughly recommend him if you’re equally careless!

Good as new! Chuffed!
Feb 092015

Even though the engine was started last year, there were a number of outstanding issues and tasks to complete the fuel system. The most concerning was the new fuel tank didn’t fit! At the time, it was just left in situ and the fuel lines connected while the engine was fired up. Refitting had to wait.

Carburetter Overflows
First, however, was the replacement of the three carburetter overflow pipes. At some stage these had been replaced by shorter pipes. Functionally there was nothing wrong with them but they should come together near the oil filter and be held in place by small clip.

The short pipes will be replaced New pipes from Burlen Fuels
Either short overflow pipes had been fitted or the originals had been cut short  New overflow pipes are available from Burlen Fuels – very expensive for what they are!

Everything is available from Burlen Fuels although they offer two lengths of overflow pipe: 19” and 25”. The length of the shorter pipe would have been marginal for the rear carburetter so I opted for 25” pipes …. just in case. With hindsight, 19” pipes should have been ordered for the front two carburetters as the distances are much shorter.

I had decided to replace these once the engine had been fitted. While it would have been much easier to shape them when the engine was sitting on its trolley, I was concerned that guesstimating suitable clearances to engine frames etc would be too easy to get wrong.

Several hours later, ready for fitting The clip securing the ends of the pipes
 Several hours later, the pipes were ready for fitting

The only slight difficulty was the overflow for the rear carburetter as access was limited once it had been shaped. The jury is still out on whether it would have been better to do this job with the engine out!

New bulkhead fuel line
Another fuel problem encountered when the engine was started was the fuel line had gone into the filter housing cockeyed, causing it to cross-thread and leak. The temporary solution had been to reverse the fuel filter however the root cause was the bulkhead section of pipe, which needed to be remade.

These earlier troubles had been caused by a combination of the pipe not being square onto the filter housing and the brass fitting supplied in the fuel line kit. The fitting had an un-threaded shoulder section which then only allowed a turn or two of thread to engage before it bottomed out on the olive. A replacement was found that was threaded to the end.

The vacuum tank needed to be removed to provide sufficient access to offer up the new pipe as it was bent into shape. I wasn’t happy with the original routing of this section of the fuel pipe, as the P-clip securing it to the bulkhead, pulled the pipe hard against the paintwork where there is an ‘X’ indentation in the toe-box.

Original routing Now routed higher on toe-box Upturn no longer fouls bodywork

By inverting the P-clip, so the pipe was supported by the clip rather than being hung from it, the pipe is routed above the ‘X’. The other problem that was cured from my first pipe attempt was the length of the downward run to the union had been cut too short, causing the upturn bend to hit the bodywork.

Installing the fuel tank …. 4th time lucky!
I take my hat off to the original fuel tank fitters, who must have developed quite an efficient technique for getting the fuel tank in place on the production line. Although, with trails and tribulations I had trying to get the tank securely fastened, it was becoming a less daunting challenge with each fitting attempt. Perhaps there is some truth in the joke about E-Types being built up around the fuel tank!

First a few minor tasks were completed. The sump was checked for pinholes as it is prone to corrosion and fitting the missing metal fuel filter at the base of the pick-up pipe. The tank and surrounding bodywork was then covered with plenty of sheets and masking tape to try and minimise the damaging the paintwork.

Fortunately sump was pinhole free Pick-up pipe – now with filter

The initial problem is the aperture of the boot space is less than the width of the seam-welded lip around the circumference of the tank. Tilting the front edge of the tank downwards doesn’t enable the lip at the rear to clear the flange for the boot boards.

There’s a gap in this flange where the boot lock attaches. So the only option I could see was to remove the lock and then tilt the tank sideways, feeding the lip through the gap vacated by the boot lock.

The most obvious approach was to raise the right side of the tank and feed it down to the left since the tank occupies the left side of the boot. However this first attempt failed as the sump attachment is proud of the base of the tank and comes into contact with the floor strengthening sections, halting progress.

So the opposite was attempted, feeding down to the right. The aim was then to shuffle the tank all the way across to the left once the flange had been cleared.

Yet just as it was nearing that point, it fouled somewhere else! It wasn’t immediately obvious what was causing the problem but eventually it was traced to the clip for the boot board. Fortunately it’s only riveted in place and could be removed.

The offending boot board clip Eventually the flange was cleared

Finally the tank was below the flange and could be manoeuvred into position once the various filler and breather pipes were attached. The boot lid drainage pipe caused quite a bit of aggravation as it had a tendency to spring out of place and push the tank away from the mounting points.

Corner bracket should
have captive nut
Breather tubes for
later S2 tanks
So near, yet so far

However, until now, I hadn’t noticed the replacement forward mounting bracket simply had a nut welded to it, rather than a captive nut within a cage. The lack of adjustability provided by a captive nut meant it was impossible to get the distance between the two leftmost mounting points to match those on the tank.

One of the mounting hole in the tank had to be enlarged by around 3mm to get the tank to fit The tank had to come out in order to enlarge the mounting hole in the tank by a couple of millimetres. Unfortunately I wasn’t able to rig up something to measure the difference in centre distances with any degree of accuracy. The tank was re-fitted but it was still a millimetre out, so it was back out for some more fettling.

This time it fitted! Well two of the three mounts did. The third bracket is moveable as it can slide in elongated holes and so would be doddle in comparison. How wrong could I be!

The original bracket had one stud missing and two of the other studs had lost most of their thread due to corrosion. It didn’t feel it was worth trying to salvage it as new ones are inexpensive. So I made the mistake of buying a reproduction bracket – not once but twice!

Damage to original bracket Neither repro brackets were usable

The first wouldn’t fit because the studs were too far apart to mate with the holes in the bulkhead. To make matters worse, I only found this out after it was powder coated. The second was ordered from a different supplier. The studs were in the right place but much smaller diameter. However, as with the previous bracket, they both just had a nut welded in place rather than the captive nut.

This mount requires both lateral and fore/aft adjustability to have any chance of alignment with the bolt. Lateral adjustment is provided by the elongated holes for mounting the bracket. The movement of captive nut provides the fore and aft adjustment. Neither of the repro brackets were useable.

Its times like this that I do get frustrated with all the suppliers – it’s just lazy ‘that’ll do’ mentality and often it would be as hard to get wrong as it would right. Although I really should have spotted the differences when they were purchased. The original one will be repaired, which is what I ought to have done in the first place. Another lesson learnt!

Fuel Sender – stumped but fixed
For some reason the low fuel light on the dash wasn’t working, yet the fuel gauge was fine. The fault was traced back to the fuel sender unit, which has a removable cover plate. So it was easy to gain an understanding of how it worked to control both the fuel gauge and warning light.

W & T terminal mechanisms Low fuel light contact strip

As would be expected, the unit uses a rheostat to vary the voltage drop across the fuel gauge and the warning light is simply a contact switch. However I hadn’t realised they were two completely separate circuits, sharing a common earth – the sender unit housing.

As the float arm rises and falls with changes in fuel levels, its pivot rotates through approximately 80 degrees. Two slider contact arms are attached to the pivot within the unit and therefore follow the same arc. They are also in contact with the sender housing and so are the electrical contact to earth.

Fuel Gauge
One of the sliders runs along the edge of tapered coil of resistance wire which is connected to the exterior T terminal. When the tank is full and the float is raised to its maximum, the full length of resistance wire lies between the slider and the T terminal – a total resistance of 196Ω.

When the tank is nearly empty and the float is at its lowest, the slider will have moved shortening the length of resistance wire between the two. At empty, the rheostat resistance is 18Ω. The fuel gauge is calibrated to display Full and Empty for these two resistance values.

Low Fuel Light
There’s a copper contact strip on the inside of the cover plate which has a small diagonal break in the copper so the two ends are electrically isolated from each other. The W terminal, connected to the gauge, makes permanent contact with one end.

When the tank is full the second slider arm is in contact with the other end of the strip and moves towards the W terminal contact as fuel is consumed. The slider eventually moves across the gap making electrical contact with the W-terminal, completing the path to earth and switching on the warning light.

I couldn’t work out why it wasn’t working. The multi-meter confirmed the internal connections were working correctly. Yet the switching wasn’t evident at the external spade connector. It didn’t make sense as a metal rivet connects the internals with the external spade terminal.

Checking with the multimeter confirmed that somehow the rivet and the external spade terminal were electrically isolated from each other. A dab of solder solved the problem but I still can’t fathom how they could not be in contact with each other.

Once it’s up and running, I’ll fill from empty to find out how many litres of fuel are in the tank when the light comes on.

The tank has since been filled from empty and it takes exactly 12 litres (2.6 gallons) before the warning light goes out. So there should be around a 50-55 miles range once the warning light comes on.

May 292014

The cars left the factory with untreated fuel tanks and so rusting from within was quite common. I wanted to seal the inside of the tank but needed to ensure that it was not of the PVC type, which is susceptible to hardening and cracking due to the increased percentage of ethanol used in modern fuels.

The other issue was avoiding the sealer blocking the small vent tubes again. Initially I’d looked at hot-dip galvanising but, after this was discounted, it came down to a choice of tank sealers from either KSB or POR-15. These both follow the same three step procedure; de-greasing, metal preparation and then application of the sealant.

In the end I opted for the KSB Gold Standard sealant. Although, oddly, the quantities sold are aimed more towards the motorcycle market. The tank needs to be rotated and rolled during all three stages of treatment to ensure all the surfaces are covered, including the baffles. Therefore it needs to be sealed to avoid leaks.

I didn’t want to ruin the final cork gaskets and so made up some silicone ones, using the left over two-part silicone used to create the mould for the heater vane.

Making silicone gaskets Masking tape retained the silicone Fuel sender gasket

The cover plate with the tube down to the fuel filter could be masked fairly easily to stop it being coated with sealant. Therefore it could be used to seal its hole in the tank. However the fuel sender couldn’t be masked effectively. So, to coating the moving and delicate parts, an aluminium disc was knocked up as a replacement.

Sealing the filler neck was slightly trickier as I couldn’t get hold of a large enough bung. A replacement bath plug from B&Q just about did the job, requiring some additional help from duct tape.

The KSB tank sealer is reasonably fluid which allows it to cover the internal surfaces fairly easily. As a result I concluded that periodic blasts of compressed air would be sufficient to stop the internal ends of the vent pipes from blocking.

Compressed air to clear vent tubes Sealed tank with de-greaser and metal prep Finally the sealant is applied

The first stage involved applying a warm diluted solution of KSB’s AQUA product to thoroughly degrease the tank. The tank then needs to be rinsed and completely dried throughout before applying their ‘Rust Buster’. Again, this needs to be rinsed and the tank completely dried before moving on to the final stage of applying the sealant.

The AQUA and Rust Buster are essential just a branded degreaser and a phosphate acid solution, to convert any surface rust. Therefore cheaper alternative options are available for these steps.

The Gold Standard tank sealer was then be poured into the tank and the tank slowly rotated to ensure all the surfaces are covered. A slow methodical approach to rotating the tank was definitely better than trying to shake the tank. The curing process doesn’t start for at least 30 minutes when it slowly becomes more viscous so there is plenty of time to get good coverage.

Compressed air was periodically blasted down the vent tubes to stop them blocking as well as every time the tank was turned. After about 30 minutes the unused sealant was drained from the tank before it started to thicken due to the curing process.

All surfaces need a light coating Draining the excess tank sealant Repainting the exterior

Unfortunately the various seals weren’t water tight so some phosphoric acid escaped over the painted exterior finish. The weak acid left light run marks in the paint which could probably have been polished out but I decided to repaint the tank with some POR-15 gloss chassis paint.

The completed tank sealed and re-painted