Firstly, apologies if this topic has been covered before (if so, please would
somebody direct me to any archives).
Background: Leaded fuel is being phased out in several places around the
world. The TR5/6 uses leaded fuel.
Question: Basically, what are the implications of using unleaded fuel in the
TR5/6, and what fixes are there?
Specifically, the issues I'm aware of:
1. Valve seat recession
I understand that we can have hardened valve seats inserted into the cylinder
head. Is this expensive? Are there alternatives, e.g. fuel additives?
2. TR5/6PI Fuel Injection System
I have heard that the fuel injection system requires the lubricating effect
of lead, otherwise it deteriorates. I have _not_ read any commentary based
on a) Lucas design data; b) Research into the lubricating properties of
leaded vs unleaded fuel; c) Experience of the effects of unleaded fuel on the
PI system.
Two potential problem areas:
i) Lucas fuel pump
ii) Metering unit & injectors
I know of many examples of PI cars running with non-standard pumps (mine runs
a fairly typical Bosch unit)--this is a pretty straightforward fix for i),
and also solves the fuel vapourisation problem.
Which brings me to ii). I know of no fix to this, other than a v. pricey
conversion to a Bosch electronic system which I believe has been developed by
a firm in the UK (Pumford?). Is the metering unit really so sensitive? Does
anybody actually know, based on real data (i.e. not "logic" such as "it's
designed to tight tolerances, so it must need the lead...") ? Are there any
additives out there which at least save the metering unit ?
I remember hearing of a "Project Green" run by the TR Register in the UK,
which I believe intended to address some or all of these issues.
Unfortunately I don't know what the outcome was.
I hope somebody out there can help. I'm sure there are quite a few other
SOL's here in Australia and elsewhere, who are watching with alarm the steady
push to eliminate the availability of leaded fuel (not to mention the gradual
reduction in octane rating...:-( ).
Here's hoping,
John Cunningham
cunningham_john@bah.com
1971 TR6 (UK spec):
Bought in 1985
Body rebuilt 1989/90
Shipped to Australia 1991
Roof hardly needed since :-))
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