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Overview
This information must be read in conjunction with notes 1, 2 and 3 appearing
below.
The Stag in standard good tune can normally operate on unleaded petrol
available from UK petrol forecourts. However, it might be necessary to
slightly retard the ignition if 'pinking' is experienced, and if you are unsure
about how 'pinking' can be identified, please seek advice from an expert garage.
If you take no action but use ordinary unleaded petrol, there is some
possibility that the (original soft) exhaust valves will wear over a long period
of time, resulting in loss
of performance and maybe causing damage to the camshaft. However, many
Stag owners have been using unleaded petrol with no ill effects, for several
years so we believe this is an outside possibility. Some Stags are already
fitted with hardened exhaust valves. Do not assume that if the previous
owner states hardened valves are fitted (without evidence in the form of
conclusive bills to prove it) that this is necessarily so!
Detailed information on use of leaded petrol and a decision tree tailored to the Stag, is available
in Technical Bulletin 19-01 which can be obtained from the TSR club office.
Engine Repairs
If it is necessary to remove the cylinder heads from your Stag for
any reason, always take the opportunity to fit hardened exhaust valves - if not
already fitted. When this change is made, it is believed that unleaded
petrol may be used with impunity, save that it may be necessary to adjust the
valve timing to prevent pre-ignition or 'pinking'. This is ultimately the
preferred long-term solution to the use of unleaded petrol. More details
are available in Technical Bulletin 19-01.
Availability of Lead Replacement Petrol (LRP)
LRP has been withdrawn from all petrol
forecourts due to lack of demand. It has been suggested this fuel was
inadequate to prevent valve recession, but there is no evidence to support this,
other than comments made by those with vested interests.
However, we advise that if you wish to use additives in
ordinary unleaded petrol, rather than rely upon finding LRP you take the 'additive' route as this places the well-being of
your Stag within your own control at all times.
Genuine Leaded Petrol
This is actually still available at a number of
specialist petrol stations, although there is a significant price premium. This petrol
is important for engines with arduous operating conditions and with very high
compression ratio's - for instance some Jaguars. It is not necessary for the Stag.
A list of petrol stations selling this fuel can be
obtained from the FBHVC website, or from the TSR club office.
Lead Substitute Additives
Additives are available in small bottles from local stores and
some petrol stations, and may also be obtained in bulk by mail order from some
classic car specialist suppliers.
Many classic car owners prefer to use additives than petrol
pumps selling �lead replacement petrol� (LRP) as the dosage is entirely
under their control, and petrol fill-up can be done at any petrol station.
There are two purposes in using additives of this nature,
- Importantly to limit valve recession - primarily wear of
valve seats causing loss of performance
- some additives enhance the octane rating of petrol to
enable use in high compression engines
The FBHVC (Federation of British Historic Vehicle Clubs) have
made exhaustive tests of a wide range of additives, and only the following
products have been approved for use. This list is complete.
| Trade Name |
Active Ingredient |
Phone |
Comments |
| Millers VSP Plus |
Manganese |
01484 713201 |
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| Nitrox 4-lead Substitute and Octane Improver |
Manganese |
0161 764 5981 |
Also claims to raise octane rating |
| Nitrox 4-star Lead Treatment |
Potassium |
0161 764 5981 |
|
| Red Line Lead Substitute |
Sodium |
01476 861195 |
|
| Superblend Zero Lead 2000 |
Potassium |
0116 286 1001 |
|
| Castrol Valvemaster |
Phosphorous |
01954 231668 |
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| Castrol Valvemaster Plus |
Phosphorous |
01954 231668 |
Also claims to raise octane rating |
| GTA Power Plus Formula 2000 |
Potassium |
01295 712255 |
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Note 1
The active ingredient in each additive is noted next to
the trade name of the additive. For the best possible results it is not
desirable to change to a different active ingredient. This advice is based on
experiences of owners of Volvo and Saab cars in use in Sweden in the 1980�s,
when turbocharger blades were found to be eroded by reaction between mixed
metals at very high temperatures. As no turbocharger is fitted, this condition
cannot exist on Stag engines.
If using any additive, adhere to the instructions with the additive, completely.
Note 2
Various �fuel line� cylinders and fuel tank solid devices purporting to
contain 'lead' and sometimes calling themselves 'catalysts' had been submitted to the FBHVC for testing (but a number were specifically
withheld from testing when requested) and none of those devices tested was found
to offer any protection from valve recession. These tests were carried out under
scientific conditions with each additive and device being tested equally. Thus,
we cannot recommend such devices.
Note 3 - Disclaimer
This information is provided in the best possible faith, but
you are advised to draw your own conclusions and decide upon your own course of
action from the information provided in this and other sources. Neither members
or officers of the TSR nor any other persons providing such information will be
held responsible in law for any consequences arising from such information
imparted.
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