|Care for the elderly
Question : I HAVE a 45-year-old Morris Minor
that is fitted with an SU carburetor.
My regular mechanic advises that
the SU carburetors require attention
although he has not specified what
type of maintenance is required.
Can you advise if such work can be
carried out at home, and is it within
the abilities of the home mechanic?
The SU carburetors are simple devices that work extremely well. They were used
almost exclusively on British vehicles up until the early 1980s when exhaust
emission regulations were tightened.
At that point, it became either impossible, or economically unfeasible,
to modify the design of the SU any further to meet the increasingly stringent
The SU carburetor consists of very
few components that can go wrong.
Very often, these carburetors far
exceed the service lives of the engines
to which they are fitted, and with very
little attention along the way.
SU carburetors do indeed benefit
from a little regular servicing, approximately once every 10,000km, or
once every two oil changes.
Start by unscrewing the
dashpot damper located on the
top of the carburetor and place on a clean surface.
Then, remove the dashpot by removing the three or four screws located at
the base of the dashpot. The dashpot assembly is removed by lifting the
entire assembly upward.
The tube on the top of the dashpot is filled with a light oil that must
be emptied and the entire assembly immersed in some form of solvent such as
paraffin or petrol to clean off any soot or dirt particles.
Take extra care not to dam- age or scratch any of the components, especially the brass A
fuel metering needle located at b
the bottom of the dashpot. cove
Reassembly is carried out in
reverse order to the dismantling procedure.
The manufacturer recommends that
the dashpot be filled with SAE10 grade
engine oil but since mono-grade engine
oils are hard to find nowadays, a quality Automatic Transmission Fluid (ATF)
can be used.
Fill to within 10mm of the top of the
dashpot reservoir and refit the damper.