Classic cars forum & vehicle restoration.

[Ray White]

[norustplease]

Just a quick word of warning, PVA isn't necessarily water resistant. If you look at the packaging you can see that some is suitable for interior use and some for exterior. The Gorilla Glue advertised on t'telly seems to be very effective as there is an exterior grade that is advertised as soaking into the materials to be joined (if permeable).
_________________
1953 Citroen Traction
1964 Volvo PV544
1957 Austin A55 Mk 1
Boring Tucson SUV

[Ray White]

[Ray White]

Lately, I have been experiencing a fuel starvation issue. The other day, the normally reliable Trundles decided to stop in the road at the bottom of our drive - as if to say " I don't like that climb up to the garage and I am staying here"

On checking the float chamber I was not surprised to find it completely empty; indicating a supply issue.

I disconnected the pipe from the carb and checked to see if it was clear; it was. The filter was also clean.

Then, with a catch can at the ready and the petrol tap at the tank turned on, I collected a generous supply of petrol but just in case there was a problem inside the tank, I removed it from the car (just two wood screws) and investigated. I also removed the tap which checked out O.K. The ethanol proof tank sealant (TOPAX) was still in good condition and showed no signs of flaking off so I surmised the problem had to be at the carb end.

Could the needle valve somehow get stuck onto it's seat?

In the Zenith FZB up draught carburettor the needle is attached to the float chamber lid and passes through the middle of a brass float. When the float rises with the petrol in the chamber, it operates a simple mechanism to close off the valve with the needle.

I couldn't see how the needle could stick in the "shut" position as everything was working as it should. However, when I went to remove the valve from the bottom of the float chamber, I noticed it was loose. Very loose.

What had happened was the valve had unscrewed itself and gradually unthreaded it's way up to the needle; shutting off the petrol supply in the process.

With the needle valve tightened down normal service has been resumed.

With Austin Sevens it is usually something simple.

[Ray White]

My original optimism has been dashed today as the intermittent fuel starvation problem is still there. Two options are a blocked vent in the filler cap (easy fix) or a foreign body floating in the the tank. (not so easy).

My frustration was made worse with the realisation that the door hinge repair has failed.
I can see me having to undo the delicate interior trim to get to the frame. I expect it needs a bracket to hold the door pillar to the roof and a more substantial repair to the hinge area.

[bjacko]

If the MG is loke a Morris there is no vent in the cap but a hole under a plate on top of the tank
_________________
1938 Morris 8 Ser II Coupe Utility (Pickup)
1985 Rover SD1 VDP

[Ray White]

[Vulgalour]

That dowel door repair is going to come in handy, I need to do that on the driver's door latch on the Lanchester, door side rather than A post side. Helped me see how it's done so thanks for posting about that.

[Ray White]

This is a problem familiar to many Austin Seven owners. These Zenith up draught carbs are made of muck metal - otherwise known as Mazak - and they all go at the same place. What happens is that the screw holding the slow running device is over tightened and the collar breaks off. Mine has been like it for as long as I can remember and I have patched it up several times.

When an old repair failed again I decided to take the easy way out and swap the carb for a bronze one that I have had knocking about for years.



Apart from cleaning it up, I swapped over the good bits from the damaged carb. These included the needle valve, the seat of which I ensured would be a good seal by mounting it - and the needle - in my lathe. I used some metal polish to get a good seat.

The choke flap and lever on the bronze carb was a home made affair and pretty crude, so I changed it and the lever. I replaced the split pins with new but the flap return spring from the Mazak carb was usable. Getting the spring set to return the flap to it's open position was more fiddly than difficult.

I swapped the spring steel clip that holds the float chamber lid; the bob weights in the lid were good so they stayed.

I also swapped over the slow running device because it had been over lightened at some time and split at the end...a common finding.

The main and compensating jets were different so I have swapped them over too. I have 0.70mm for the main and 0.75 for the compensating which seems to be the normal combination.

The correct round head brass screw for locating the slow running jet and the brass adjuster lock nut were also both transferred.

A good clean up and the replacement carb is ready to go.

Whether or not the engine will perform as it should is yet to be established.

[Ray White]

At the time of writing I have to report one or two niggles with fitting the carb.

After ensuring the surfaces were perfectly flat, I made a gasket using the correct paper. I used hole punches for accuracy then cut it to shape. I de greased all the surfaces and applied a little Wellseal before fitting to the manifold.

Unfortunately, There is insufficient room under the top flange (on one side) for a nut AND a spring washer. I am not happy with just a couple of brass nuts to hold the carb to the manifold; I suppose I could use a dab of thread lock?

Another difference is that the bronze flange is thicker than the Mazak one which might mean finding some slightly longer BSF bolts.

Also, the slight difference in carb body length means the existing rod for operating the choke is slightly too short so I will have to make a new one.

[Ray White]

The "new" carb is now fitted to Trundles and I must say it looks nice. I have managed to get it set up in the garage...but what will it will be like on the road ? I know it prefers to be run on E5 petrol.

These old Zenith carbs were originally tuned by switching to different size jets...but of course today's user has to make do and mend. As this carb is using the jets from my old carb I am hopeful that the performance should be similar.

One potential improvement should come from the butterfly spindle which compared with the Mazak has very little wear; no more disguising the potential cause of a lean mixture with blobs of grease!

On a different matter, I was pleased (to say the least) to see the dynamo is now charging as it should. I had been worrying that the ammeter was only showing "charge" at high revs. It is now switching from discharge to charge at a much more sensible engine speed. This may have been related to the loss of residual magnetism - caused by a long period of inactivity - which I have rectified by "flashing" the dynamo field coils. This involves taking a cable from the battery positive terminal (- earth) to the dynamo for a short time with the engine running.

I may have mentioned (a long time ago) that my car is fitted with a later 'Ruby' dynamo which is regarded as a much better instrument. However, it lacks the built in resistor for the Summer/Winter charge setting but I have resolved that issue by adding an auxiliary resistor; better that, than overcharging the battery.!

[alastairq]

Splendid stuff.

I do wonder why Trundles runs smoother on E5 rather than E10?

Mind, I have only used SU carbs, which are more user friendly with regards to mixture settings than fixed jet carbs. Not that I've had to reset mixtures!

Will we see you resorting to 'numbered' drills when fine tuning the jet sizes?
_________________
Dellow Mk2, 1951 built, reg 1952.
Fiat 126 BIS
Cannon special [1996 registered. Built in 1950's]
----------------------------------------------
Ford Pop chassis, Ashley 1172 bodyshell, in pieces.

[Ray White]

[alastairq]

[Ray White]

I think we must face the possibility that the future for petrol - of any kind - is bleak.

I just go with the flow. If it gets too scarce or too expensive then that is life.