Austin Classics

The Zenith 26VA carburettor was first fitted to all UK models of the Austin 10 (excluding the sports model) in November 1933 starting with chassis number 28,000 until the introduction of the Cambridge in July 1936.

The new Zenith "V" series carburettor introduced improved fuel atomization and uniform distribution of the atomised petrol. This resulted in more power and better efficiency over the old "U" series. In fact Zenith proudly claimed that the V series was perfect at the time it was introduced and advertised that "There is no finer carburetter on any engine".

The 26VA was produced in a number of different configurations for a variety of cars available at the time. Each car manufacturer would request their own specification for the engine they were using and Zenith would manufacture the carburettor to that specification and there would be a unique contract number. The Zenith 26VA as originally found on an Austin 10 had the contract number C541 stamped underneath the 26VA model number where the fuel line enters the carburettor. To further aid the identification, 26VA's that were fitted by Austin to the 10 were stamped on the flange where the carburettor is attached to the manifold with the number "10". Rather confusingly however there are two variations of the specification for the 26VA supplied under contract C541. Austin changed the choke tube size from 19mm to 21mm in 1936 and the jet sizes were modfied to suit, but the contract number was never changed. As a result it is not possible to identify the 19mm and 21mm from the contract number, the only way to determine the exact model requires some dismantling to read the choke size cast into the opening of the choke tube, the example below shows a 19mm model.

IMPORTANT For the Austin 10 owner looking for a replacement carburettor it is important that the correct version of the 26VA is found. The 26VA carburettor may look the same from an Austin 7 for example but it would not make a suitable replacement for an Austin 10 as the specification is different. Allthough the jets can be easily changed to suit the choke tube that is part of the casting and can not be modified is to small at only 17mm.

TIP Although the main body of an incorrect model 26VA is not usable most of the the parts including the bowl, strangler and cowl can be used as spares to repair your own carburettor. If you are unable to locate a genuine Austin 10 26VA, don't despair as other 26VA carburetors can be used providing you can find one with a 19mm or 21mm choke tube. It will just take some effort as the cowl will need to be removed to see the choke size.

To overcome the effects of petrol vapor condensing on the inlet manifold walls and not reaching the combustion chamber when the engine is cold, the 26VA has a strangler flap inserted over the air intake. When the control from the dash is operated the flap closes the air intake and when the engine is turned over the resulting vacuum is directed entirely on the jets of the carburettor. This results in a very rich mixture being supplied and the engine is able to start readily.

Slow running adjustment

The carburettor settings will generally not require altering, however should it be found that the slow running needs improvement it can be adjusted with the slow running air regulating screw.

Before attempting adjustments warm up the engine to its normal operating temperature.

Removal and re-fitting

It is likely that when the carburettor is removed that the manifold gasket will not be re-usable and a replacement should be installed to ensure that no air can leak at the join.

IMPORTANT The 26VA carburettor is made from a zinc alloy, sometimes referred to as Mazak. Take care when tightening screws and bolts as the threads in the casting can easily be destroyed, in particular when tightening the bolts that secure the bowl, take extra care.