An article from Chairman Malcolm Marchbank

Spring has sprung and those classics will be
starting to come out of hibernation. After months
in the garage with the occasional start up to
keep it ticking over, your engine can suffer. I have
personally experienced this after months of an
engine sitting during restoration work and being
moved from one side of a workshop to another.
Once the work was complete, trying to drive
away from the workshop, my T2 Bay Campervan
wouldn’t accelerate down the road. Reason –
fouled spark plugs.

I have also had a spark plug with a closed gap
(don’t even ask how that happened, but it
involved losing part of the carburettor through
the engine… lucky it didn’t do any other damage!)
The condition of your spark plugs can make a
massive difference to the running of your engine,
so it’s worth checking them every so often,
especially after a period of time unused.
Hopefully the following information will help to
make you a spark plug expert.
Before starting work on checking your plugs, it is
helpful to have the right tools to hand; accessing
the rear two spark plugs at cylinders 1 and 3
can be a real fiddle, especially on later twin-port
engines where access is further compromised
by the inlet manifolds. A short 21mm socket and
universal joint may give you a bit more flexibility.
When checking the plugs, it can help to remove
each lead and plug individually so that you don’t
get them mixed up. This will cause an incorrect
firing order and your engine will not run.
When removing the ignition lead from the plug,
be sure to pull it off by the connector, not the lead
itself, as you’ll run the risk of pulling the lead off
the connector (trust me!)
If you notice any damage to a connector or if a
lead is a lose fit, it is best to go out and buy a new
HT lead set.
Make sure you have the socket on the plug
properly when you’re undoing them and it’s also
best to do all this while the engine is cold to avoid
burning yourself!
Once the plug is out, take a good look. Is it brown,
grey, sooty or oily? If the engine is running right,
it should be light brown or grey. If it is sooty but
dry, your engine is running rich and not burning
all the fuel. If the insulator is white and flaky then
your engine is running too lean. Either way, you’ll
need to tune your carb to adjust the fuel/air
mixture.
If the plug is wet and oily, there are a couple of
possibilities. The first is that you’re not getting
a spark, in which case you may have noticed
a misfire. If this is the case, check the HT lead
connection at the plug and also where it pushes
into the top of the distributor cap.
A worse scenario is that your engine has worn
piston rings and/or valve guides, which means a
rebuild is on the cards. If there is serious carbon
build up on the plug, or what looks like molten
bits of metal, chances are your ignition timing is
out.
Whatever their condition, while the plugs are out
of the engine they will benefit from a good clean
up using a brass wire brush. While you are at it,
check the spark plug gaps using a feeler gauge.
For most air cooled engines the gap should be
0.024” or 0.6mm, however check your workshop
manual because the gap will be different on
some engines. If the gap is correct, the gauge
should slip in and out without much resistance.
If it is too loose, you can adjust it with a gentle
squeeze in a vice to close it slightly, or if the gap is
too tight, carefully prise open the contact with a
flat bladed screwdriver.
Spark plugs should be checked every 3000 miles
and replaced every 10,000 miles as part of your
service routine. If you suspect a poor running
engine there is no harm fitting new ones sooner,
they are relatively cheap for a set.
When refitting, always start screwing the plug
back in by hand, only using the socket for the
final tightening, otherwise you risk forcing a cross
thread. If you feel any resistance early on, unscrew
and carefully try again

The mechanic has noticed a recent uplift
in questions and concerns surrounding the
upcoming introduction of E10 fuels. The
following is information provided by the
Federation of British Historic Vehicles Clubs
that we hope members will find useful.
Federation of British Historic Vehicles
Clubs – Introduction of E10 petrol
After an extensive consultation process, the
Department for Transport has announced that they
will legislate to introduce E10 petrol as the standard
95-octane petrol grade by 1 September 2021. They
will also require the higher-octane 97+ ‘Super’ grades
to remain E5 to provide protection for owners of
older vehicles. This product will be designated as the
‘Protection’ grade.
The introduction of the 95-octane E10 grade and the
maintenance of the Super E5 protection grade will be
reviewed by the Government after 5 years to ensure
they remain appropriate to the needs of the market:
In relation to the E5 protection grade, such a review
will examine market developments over the period.
HM Government have sought to reassure FBHVC
members and historic vehicle owners that, without
a suitable alternative becoming available, it is highly
likely the Super E5 protection grade would continue
to be available.
Filling stations that stock 2 grades of petrol and
supply at least one million litres of fuel in total each
year will need to ensure one product is the Super E5
protection grade. While not all filling stations meet
these criteria, almost all towns across the UK will have
a filling station that supplies the ‘Super’ grade and
currently one major retailer, a national supermarket
group, has committed to offer the product. The main
exception to this is in certain parts of the Highlands,
north and west coast of Scotland, which will be
covered by an exemption process and allowed to
continue to market the 95-octane E5 grade.
The Federation therefore recommends that all
vehicles produced before 2000 and some vehicles
from the early 2000s that are considered noncompatible with E10 – should use the Super E5
Protection grade where the Ethanol content is limited
to a maximum of 5%. To check compatibility of
vehicles produced since 2000, we recommend using
the new online E10 compatibility checker: https://
www.gov.uk/check-vehicle-e10-petrol .
It should be noted that some Super E5 Protection
grade products do not contain Ethanol as the E5
designation is for fuels containing up to 5% Ethanol.
Similarly E10 petrol can contain between 5.5%
and 10% ethanol by volume. Product availability
varies by manufacturer and geographical location
and enthusiasts should check the situation in their
location.
Latest News:
The federation’s fuels specialist Nigel Elliott has
received some new questions with regards to
ethanol and the use of E10 in historic vehicles and his
thoughts are as follows:
There are three key areas of concern with Ethanol
compatibility with historic and classic vehicle fuel
systems:
‹ Corrosion of metal components
‹ Elastomer compatibility – swelling, shrinking and
cracking of elastomers (seals and flexible pipes)
and other unsuitable gasket materials
‹ Air/fuel ratio enleanment
Corrosion of metal component
Ethanol has increased acidity, conductivity and
inorganic chloride content when compared to
conventional petrol which can cause corrosion
and tarnishing of metal components under certain
conditions. These characteristics are controlled in the
ethanol used to blend E5 and E10 European and UK
petrol by the ethanol fuel specification BS EN15376 in
order to help limit corrosion.
Corrosion inhibitor additives can be very effective
in controlling ethanol derived corrosion and are
recommended to be added to ethanol in the
BS EN15376 standard. It is not clear if corrosion
inhibitors are universally added to ethanol for E5
and E10 blending so as an additional precaution it is
recommended that aftermarket corrosion inhibitor
additives are added to E5 and E10 petrol.
These aftermarket ethanol corrosion inhibitor
additives often called ethanol compatibility
additives are usually combined with a metallic
valve recession additive (VSR) and sometimes an
octane booster and have been found to provide
good protection against metal corrosion in
historic and classic vehicle fuel systems.
Elastomer compatibility
As the ethanol molecule is smaller and more polar
than conventional petrol components, there is
a lower energy barrier for ethanol to diffuse into
elastomer materials. When exposed to petrol/ethanol
blends these materials will swell and soften, resulting
in a weakening of the elastomer structure. On drying
out they can shrink and crack resulting in fuel leaks.
Some aftermarket ethanol compatibility additives
claim complete protection for operating historic and
classic vehicles on E10 petrol. The FBHVC is not aware
of, or has tested any additives that claim complete
fuel system protection with respect to elastomer and
gasket materials for use with E10 petrol. The FBHVC
therefore recommends that elastomer and gasket
materials are replaced with ethanol compatible
materials before operation on E10 petrol.
Air/fuel ratio enleanment
Ethanol contains approximately 35% oxygen by
weight and will therefore result in fuel mixture
enleanment when blended into petrol. Petrol
containing 10% ethanol for example, would
result in a mixture-leaning effect equivalent to
approximately 2.6%, which may be felt as a power
loss, driveability issues (hesitations, flat spots, stalling),
but also could contribute to slightly hotter running.
Adjusting mixture strength (enrichment) to counter
this problem is advised to maintain performance,
driveability and protect the engine from overheating
and knock at high loads.
Modern 3-way catalyst equipped vehicles do not
require mixture adjustment to operate on E10 petrol
because they are equipped with oxygen (lambda)
sensors that detect lean operation and the engine
management system automatically corrects the fuel
mixture for optimum catalyst and vehicle operation.
Operating classic and historic
vehicles on E10 petrol
If you should decide to make the necessary vehicle
fuel system modifications together with the addition
of an aftermarket additive to operate your classic or
historic vehicle on E10 petrol. The FBHVC strongly
recommends that you regularly check the condition
of the vehicle fuel system for elastomer and gasket
material deterioration and metallic components such
as fuel tanks, fuel lines and carburettors for corrosion.
Some plastic components such as carburettor floats
and fuel filter housings may be become discoloured
over time. Plastic carburettor float buoyancy can also
be affected by ethanol and carburettors should be
checked to ensure that float levels are not adversely
affected causing flooding and fuel leaks.
Ethanol is a good solvent and can remove historic
fuel system deposits from fuel tanks and lines and
it is advisable to check fuel filters regularly after the
switch to E10 petrol as they may become blocked
or restricted. If your vehicle is to be laid up for an
extended period of time, it is recommended that the
E10 petrol be replaced with ethanol free petrol which
is available from some fuel suppliers. Do not leave
fuel systems dry, as this can result corrosion and the
shrinking and cracking of elastomers and gaskets as
they dry out