FWD Newsletter - October 98
Roger Parker roger.parker@virgin.net
Roger Parker roger.parker@virgin.net
I am just able to squeeze a mention here of the MG
Marque day at Gaydon held on 9th August. What a superb day confirmed
by the fact that the top of my head still glows a deep red from
the glorious sun all day. The layout seemed to this observer
to be arranged to favour the MGF, not surprising as Gaydon is
a Rover operation and the F is the current product. I did note
some comment from owners of other models on the lack of any other
focal point specific to their models. On the FWD front I was
initially a little perturbed at the positioning of all FWD cars,
excepting the MG 1100 and 1300, on the bank opposite the museum.
However I noted that when down by the museum you could see the
MGFs next to the museum, then a sea of all sorts of MGs in the
main car park. Then beyond quite clear for all to see, was the
vast turnout of FWD cars filling the banked area, looking just
like a scene from 'Zulu' where the warriors gathered on the high
ground before an attack - quite an imposing sight, especially
since there was over 85 cars there.
The Great Unleaded Debate Continues...
One of the frequently repeated questions asked during
the day and one that has been repeated so many times recently
is the one concerning what has to be done to enable unleaded to
be used. This question is one that will grow louder and louder
as the leaded 4 star pumps start to disappear from UK forecourts.
To respond I have spent quite some time looking into the subject,
and been quite vocal on the subject through various mediums.
I am pleased to say that this has not gone unnoticed within Rover
and I have had some contacts, which have confirmed (unofficially)
almost all that I have said. Where there are differences they
are in 'matters of degree' rather than being different, and that
just about sums up this whole issue!
The first thing is very, very clear, which is that
Rover will not give any retrospective approval to the use of unleaded,
unless that car was approved at the time of production. There
may be an odd exception to this where an approved conversion was
made available to update some, but the general rule is set in
stone. For the FWD cars this means that only the very late MG
cars will have factory approval.
Unleaded fuel isn't really, as it contains traces
of lead, something less than 0.013grams per litre, whilst normal
leaded contains up to 0.15grams per litre. Compare this with
the 0.4grams per litre of just a few years ago and its clear why
problems exist. Of interest is the fact that many burnt valve
problems, from those supposed good old days when there were higher
levels of lead in fuel, were actually caused by too much lead.
Now that's a different angle isn't it?
The lead in fuel is a solid compound and these lead
salts would collect together and hold the valves just off the
seats so that heat transfer from the valve was drastically reduced.
This would lead to overheating and burning of the valve. Those
with experience from 30 plus years ago will recall seeing 'balls'
of lead salts in combustion chambers when carrying out those frequent
decokes and valve grinds. Like all good things too much is bad
for you!
Lead has several very useful functions with the lubrication
and slowing of the burn rate being two of the main ones. Take
it away and the fuel burns faster and hotter, which can be beneficial
to maximum power. (Assuming the engine doesn't detonate) Without
the lubricating effects of lead the valves (exhaust) stick to
the seats and rip away small pieces, which over time causes the
valve to recede into the head, and which can be seen in reducing
valve clearances. With bits of seat now stuck to the valves they
won't seat properly, so the valve overheats and can burn through.
The exhaust guides can also show deterioration having lost lead's
lubricating effects. Note that the rate of erosion once the lead
is removed starts at a very slow rate and increases very dramatically
the hard the engine is loaded and the higher the revs used.
Another area that can suffer are the pistons where
the piston material can erode in the area of the rings. This
results in the machined gaps for the rings, usually the area between
the top and second ring, widening to the point where the rings
can't work properly. Once again the rate of erosion is like the
pattern for the valves and seats, except that it takes much harder
use to create problems. For example the Sherpa van with the 'O'
series engine was the only 'O' series vehicle to suffer, which
was down to heavily laden vans with lead footed (the only lead
input!) uncaring drivers travelling flat out for hours on Motorways.
The simple cure for these was to introduce a reinforcing insert
into the piston.
Lets now take a look at which FWD cars have factory-unleaded
approval and what is needed for those that don't. Remember that
the life expectancy of any engine is totally dependent on the
manner of it's use. Conversion to use unleaded helps maintain
original levels of reliability, but overall life expectancy is
still dependant on it's manner of use...
The 'A' Series Engined cars...
The MG Metro with 12HF prefixed engines are unleaded
from the factory. As a quick reference the cars will have to
have the late type of high petrol filler cap. There are a whole
series of other spec 1300 Metro engines that also have approval
and these have 12HE prefixes. Not all of the HE series have approval
though, look at the following list to see which are. Engine codes
with (12H) E24, E25, E35, E39, E40, E41, E42, E48, E67, E68, E69,
E70, E71, E72, E73, E74, E75, F01, F02, are all unleaded compatible.
A slight anomaly seems to stem from the Swiss and
German 1986 on model year cars. My (personal) understanding is
that these models were able to run unleaded and the parts used
in the cylinder heads seems to support this, with the use of inserts
and guides as found in the unleaded spec engines. This view has
been reinforced with back door information confirming that the
company was aware of the situation where many Swiss owners frequently
accessed the German Autobahns, and this type of use demanded better
protection.
The story of the route the Mini took to get into
Japan is of interest, and I hope I can recall the story as told
me with reasonable accuracy. Minis into Japan started very much
like the 'Grey Imports' we currently receive the opposite way.
The demand for Mini's meant a steady flow were finding their
way into Japan, yet with the very soft cast iron heads and valve
seats erosion with unleaded use was guaranteed. To investigate
this a new Mini was taken off the line and run in on leaded on
the first day. At the end of the running in mileage it was checked
over and valve clearances accurately set. The second day it was
filled with unleaded and run hard all day, covering something
around 500 miles. At the end the valve clearances were checked
and showed a very slight reduction of clearance on cylinders 2
and 3. (Hotter running) The next day the test continued but
the engine died before the end of the day with massive valve/seat
damage.
This test illustrated several things, 1, the cast
iron of A series heads at that time was totally unsuitable for
unleaded use, and 2, there was a 'memory' effect following the
change from leaded to unleaded. This memory would be longer had
the continuous use of leaded fuel been over a longer period/mileage.
Finally the test was severe and intended to be so, which is what
the manufacturers have to cater for when it comes to providing
unleaded approval. So the same Mini gently used to and from the
shops with never more than the odd use of anything more than a
gentle throttle would almost certainly last many years using the
same unleaded fuel.
The point to make here is that the rate of damage
following from unleaded use in an engine not engineered to run
on it varies very considerably. From very little different to
the engineered engine at low engine loads and speeds, with a massive
increase in this rate as the engine load and speed rises. With
most owners falling into the gentle user bracket this means that
a change to unleaded is not going to see a sudden and catastrophic
engine failure. In fact as these engines will have been running
leaded for a long time the 'Memory Effect' plus gentle use will
quite conceivably see this engine running normally for many thousands
of miles and year in time. Take it on the racetrack though and
expect the engine to be rough by the second event! Clear as mud?
You bet!
The MG Metro Turbo was never engineered to run unleaded
but does benefit from the use of valves and guides that are high
enough quality. Inserts that are listed are also the same units
as fitted to unleaded naturally aspirated Metro engines so the
fitting of these will enable the car to use unleaded. Those worried
about the turbo should bear in mind that these turbo units are
also used with fully unleaded engines and as such need no modifications.
Conversion of 'A' series engines to be able to
use unleaded, with a reasonable life expectancy, involves just
the conversion of the head. This involves having suitable exhaust
seat inserts and exhaust valve guides fitted.
The 'O' Series...
The 'O' series was around for many years before it
was developed for use in the Montego then Maestro FWD cars, first
with the introduction of the MG Montego EFi in April 1984, followed
shortly after by the identical engine being used in the MG Maestro
EFi. These engines carried over quite a number of parts from
the earlier 'O' series engines, including the same valves, guides
and seats. The seats and inlet valve changed in 1986 when the
20HD series engines appeared, but other items such as guides and
exhaust valves continued to the end of production. I have also
been told that the 'O' series gained engineering approval for
the use of unleaded back in 1979, which dovetails with the development
of the Federal spec engines intended, but never used, for the
MGB.
The official approval for these engines to run unleaded
did not appear until 1990. Interestingly there were no engineering
changes listed, only a new ignition ECU for the MG Maestro, which
continued with the Lucas engine management, and a new Rover developed
engine management system (MEMS) for the MG Montego. It is also
worth pointing out that the later catalyst version of the engine
used the Lucas system, and whilst MG Maestro/Montego was not listed
as being available with them if the engine code is 20HF51 then
this would be a catalyst spec.
Just like the Metro there were cars sold in Switzerland
and Germany well before the UK approval of unleaded appeared.
I recall data read over 10 years ago indicating these were expected
to run unleaded and I note that there is a specific separate ignition
ECU listed for the 'Swiss' market cars. (The 'Swiss' specification
is the only alternative listed in this field)
The detail of this data clearly shows any injection
MG engine 20HD05 107298 on, matches the specification of the cars
running unleaded so can be regarded as fully engineered with no
need for any engineering changes whatsoever.
The implications of the information to hand also
points towards the fact that the earlier engines have also been
engineered to run unleaded. My experience with of many, many
thousands of miles with a tuned early 'O' series, and many hours
run flat out on a dynamometer with no power losses or any form
of internal damage, tends to help support this view. (Especially
when comparing with the Mini test!)
The MG Maestro/Montego Turbo have two distinct engine
specs, the earlier 20HC41, 20HC85 and 20HE15 versions which do
not have approval, and the later 20HF50 which does. The factory
conversion follows a slightly different path to that used for
the injection engines, as the engineering route taken to unleaded
by Rover involves a new piston. This reduces compression by half
a ratio, 8 to 1 against 8.5 to 1 of the leaded engines, with other
parts including piston rings being carried over.
At the start of the 1989 model year the Montego Turbo
also gained from a new combined engine management system called
ERIC. This was with engines coded 20HE15. This engine can be
associated with the later unleaded versions by virtue of the ERIC
system, but reference should be made to the engine codes to confirm
which spec the engine is.
Earlier Turbo engines have almost all that is needed
to be unleaded compatible, and certainly there is no need for
any changes above the head gasket line. This leaves just the
lower part of the engine and the fact that the new pistons only
drop the compression by half of one ratio. My observations of
many high boost turbo engines indicate no damage due to the use
of unleaded. Sealing at the head gasket line being another story
though!
One very specific aspect found when comparing unleaded
to leaded with the Turbo engine is fuel efficiency. The economy
with 95 RON unleaded is very significantly reduced under similar
driving conditions, read that being between 10 and 15%! Use of
98 RON super unleaded reduces that deficit slightly. The reasons
almost certainly are the need to re-tune the engine to take into
account the different combustion characteristics, which with this
engine management system is not possible, except with the early
ERIC engines that can have the later unleaded ECU fitted.
The 'R' and 'S' series engines...
These engines were used in the MG Maestro 1600 from
introduction in spring 1983 to the arrival of the 2 litre 'O'
series version in October 1984. The 'R' series is by far the
most common, but with a common base design both can be treated
the same as far as the engineering is concerned. Both have cast
iron cylinder heads they have the same limitations as do 'A' series
engines. This means that the same procedure for converting is
also applicable, with the addition that a replacement 'S' series
cylinder head, prepared for unleaded use, is available from Rover
as a replacement part - at a price well above the usual engineering
conversion though! This doesn't list the use of any valve seat
inserts, so may well involve some form of induction hardening
process to the casting, in much the same way as was done to later
MGB heads for North America.
Tuning...
This doesn't just mean power tuning, but also the
basic setting up of standard engines. When converting to unleaded
you have to consider the other implications from changed combustion
characteristics. As I mentioned earlier the removal of lead from
the fuel increases the speed of burning, so the burn is completed
faster and the temps achieved are higher. There is also the aspect
of different octane ratings for fuel, which is another subject
and one that has been around during times of leaded only fuels.
In practice most UK conversions revolve around the
situation of converting from using 97RON leaded to 95RON unleaded.
The drop in octane has to be dealt with and this compounds the
different combustion characteristics of the unleaded fuel. As
a start point the usual practice is to retard the base ignition
timing by 3 degrees, assuming that you have a distributor, so
this advice applies only to 'A' and 'R' engined MGs. These engines
have the simplicity of being owner adjustable to suit whatever
fuel rating you use.
'O' and 'S' engined MGs have all ignition functions
controlled by a microprocessor so simple alteration is not possible.
Usually retention of the original control unit will provide normal
operation, with the advantage that there is a power bonus to the
specific leaded spec control units. In the event of detonation
the simplest solution is to use 98RON unleaded, which then moves
the fuel octane spec above the minimum that the engine was originally
tuned to run on. The use of a later unleaded spec control unit
is an option to enable the use of the cheaper unleaded on the
'O' series as there are appropriate spec units available. The
MG 'S' engine was not available with an unleaded option so there
isn't a true replacement, however other models using the 'S' engine
did enter the unleaded period and so a control unit from one of
these will provide a viable option.
Power Tuning...
This is an area of interest to many and in simple
terms there is still great scope for engine modification, with
the proviso that compression ratio's have to be kept lower. (Below
9.7 to 1 as a general guide for UK fuels) If the compression
is too high then to combat detonation the timing has to be retarded
so much that there is a significant loss of power, which defeats
the whole object of tuning. One consideration in this area is
that for the best returns in power terms the use of 98RON unleaded
has to be the choice.
Another very serious consideration here is that like
most 2 valve per cylinder engines, there are considerable gains
to be had from cylinder head modifications done by an expert.
Combining power and unleaded modifications is a very cost effective
move as two goals are achieved with just one lot of work. Plus
the costs of unleaded are usually reduced from when this is done
in isolation.
If the choice is just to have the head converted
to unleaded with no mods, the usual result is about 5% more power,
even when accounting for the retarded timing. This is due to
the better cuts on the valves and seats allowing better gas flow.
If the removed head condition is anything other than perfect
(very unlikely) then the gains will be greater still.
Additives...
A simple area at the moment as there is no device
or additive that has any official approval following recognised
testing in the UK. There are apparently going to be approved
additives that will have been tested and are intended to provide
the same level of protection that we currently enjoy from leaded.
Legal wrangles in the background have/are delaying this development
and it may be some time yet before they appear.
There are many 'devices' and other 'additives' currently
available with claims to achieve various levels of protection
and alteration of emission levels. I have already mentions the
wide variables that have significant effects on engine life.
In addition to those, I can quite easily introduce changes to
the running and emissions from an engine by many simple changes
that don't cost anything.
Consequently I do not believe that these achieve
anything that couldn't be achieved by other cheaper and simpler
means. However, my mind is still open to receive the one that
actually does work.
And finally...
Contrary to what too many think the conversion to
unleaded doesn't mean that you HAVE to use unleaded. You now
have the option of using leaded or unleaded as the fancy takes
you. If the choice is on cost grounds then do some careful tank
to tank cross references as the conversion to unleaded does quite
often lead to reduced MPG, enough to cancel out cost savings at
the pump on occasion.
Now to help turn my previous ramblings into practical
terms Neil Cairns has done a comprehensive piece on how he converted
his MG Metro. Over to you Neil...
Going Lead-free (as cheaply as possible)...
Some MGs are worth more then others, and far from
the top price range is the humble MG Metro 1300. We are told
that very soon leaded petrol will be phased out, and cars that
cannot use unleaded fuel will be just a lump of scrap metal.
The problem is that the Metro/Maestro/Montego range, in the MG
form, are not of high value, (yet) and in fact buying a proprietary
modified head, and having it fitted by a garage, can quickly approach
half the value of some cars! Not a recipe for many to survive
past that fateful day of no more lead.
So how do you modify a MG Metro and keep the costs
down? Being of a somewhat tight-fisted but mechanical nature,
I set myself that very task. Our 1989 version is leaded, only
a few models away from the last MG Metro's that were fitted with
the later unleaded cylinder head. The 'A' series in this car
is not really any different form all the others that use the engine,
in the mechanical sense. It is quite a simple matter to unbolt,
as you would for a simple decoke.
It is best to leave as much as possible UNTOUCHED,
if the car was running well. The manifolds can be unbolted and
pushed to the rear, after the exhaust to gearbox mounting has
been undone! This is underneath the gear selector rods at the
back/bottom of the engine. (Unless it has been forgotten/removed
by a previous owner - Rog) The rest is really rather obvious
for removal, remembering to catch the antifreeze mixture in a
bowl when you undo a radiator pipe to drain the engine. Beware
of seized up studs on the thermostat housing. (Bolts on later
engines) Note that the Metro doesn't use the bye pass hose between
the top of the water pump and the head, as used on earlier 'A'
series engines.
To keep costs down I did all my own labour. The
head once removed was stripped down completely, with all studs,
valves and temperature sensor removed, and all carefully numbered
as to where they went. (You will be re-using the inlet valves)
The head was then sent off for the unleaded, hardened steel valve
seat inserts to be fitted. I used a company called 'Farriday
Engineering' of Wolverhampton (01902 739690) who fitted the seats,
eight new guides, recut the seats and supplied four new exhaust
valves already ground into the very hard seats. The cost, with
£22 carriage by Parcel Force included, was £11.89.
VAT bumped this up to £130.89. Mentioning that I was in
the MGCC saved me about £20. I bought a head set for just
£5 at the MG Day at Stoneleigh, Warwickshire, which included
valve seals.
The head was away just 3 days, and came back on the
Friday in time for me to re-assemble it on Saturday. I re-used
the valve springs as they were all the same height when checked
on a flat surface. The inlet valves needed only gentle lapping
to get good seating. At a push I was told I could use the old
exhaust valves, but decided that this was risking too much. Those
suitable for unleaded cost just £6.50 each and remember that
this was a cost cutting exercise as a test for the impecunious.
It only took two hours to pull the head off and strip it down.
Re-assembly took three hours, but this included cleaning and
lapping in the old inlet valves. Cleaning and fitting back onto
the block took about an hour and a half, and was the fiddliest
as both the block and manifolds had bits of old gasket stuck to
them.
Note that very little was disturbed, as the engine
was performing quite satisfactorily prior to the decision to go
lead free. I did clean up the carb with carb cleaner, though
the air filter and spark plugs were renewed only 3000 miles before,
during the last service. At 72,000 miles there was no wear lip
at the top of the cylinders, showing regular servicing with oils
and filter changes pays off. (I fully agree - Rog) The MOT test
level of air and fuel mixture was, from the deposits in the cylinders,
rather weak. (Not an unusual situation -Rog)
I am not sure I like steel nuts on the manifolds,
brass is better. I found those on this Metro were in fact loose
on removal, but not enough to cause leakage. It was fiddly getting
the nuts off the manifold in situ, but saved removing and disturbing
the carb, it's linkages and cables, as well as those difficult
to reach exhaust joints.
On refitting, everything needs to be clean, pushrods
back into the hole they originally came from, so that they match
up with the wear on their rocker and follower. Head studs need
pulling down, then torque loading to the correct setting. (50lbs/ft
on the MG Metro 1300) Set the tappet clearances, 12 thou cold,
refit the cleaned and correctly gapped plugs, leads and coil.
The latter mounting on one of the head studs.
I then started the engine and had a bit of a shock,
as it was so quiet. Perhaps the tappet clearances were a bit
wide before. On Saturday afternoon the tank was filled with unleaded
petrol, and I did a 30-mile run. There was no pinking, surprising,
as the compression ratio on this car is quite high. The only
adjustment I had to do was increase the idle speed a little.
With garage hourly rates up past £25 per hour, a DIY job
such as this must be a bargain.
Neil Cairns.
Neil has pointed out the use of the steel nuts on
the manifolds. I have seen the same degree of loosening on many
a Metro. It seems to come from the loosening of the nuts through
thermal loadings, but also from the shrinking that occurs to the
manifold gaskets. This occurs gradually and leads to a noticeable
increase in engine noise, and slightly rougher engine. The usual
characteristic 'chuffing' associated with a leaky gasket not being
heard until a more serious leak occurs. The difference that a
simple gasket replacement makes and use of brass nuts is quite
marked, and well worth the effort.
Before singing off a gentle reminder that we are
approaching the time of colder weather and generally less favourable
weather conditions. Time to check (change) the antifreeze, inspect
the wiper blades, washers, and lights.