----- Original Message -----
From: Colin Brown <ccbrown@whitesea.co.uk>
To: <MGS@autox.team.net>
Sent: Saturday, November 27, 1999 3:41 PM
Subject: Leaded/Unleaded in the UK
Hi, Colin,
I, too, did some research on this...
>
> In my '67 B I am using the Castrol Valvemaster ( from MGOC or
> Halfords) to dope each 25 litre fill of Super Unleaded ( 98 Octane),
> but this grade costs about 5% more than regular 95 Octane Premium
> Unleaded and is not offered on all forecourts.
> ( For US listers, fuel here costs about $5/US gallon, so these things
> really matter!)
LRP in the UK has no British Standard and uses potassium which, apparently,
didn't fare too well as lead replacement compound in the (unofficial) tests.
Valvemaster + uses phosphorus.
>
> I challenged Castrol to justify their advertising claim that they were
> offering a cheaper option to 4*leaded fuel ( soon to be banned), but
> they are assuming of course that we ( with MGBs) should be prepared to
> click back our ignition timing to use 95 Oct unleaded fuel.( I am
> not!)
My B is 9.7:1 compression, with a CAEH 864 cam and 32cc chambers. It was
tuned to run on 4* and on 95 octane unleaded and Valvemaster +, it runs
better than it has for ages-no pinking and a better tickover.
I suspect that the quiet reduction in tetraethyl lead in 4*- from 14% in
about '81 to 3.6% of late ( figures from memory) has undermined the
efficiency of 4*. When I try unleaded in my Triumph 2.5PI saloon, I expect
that any discernible difference might prove this.
> >From another authoritative source I learn that Valvemaster+ doped at
> 25mls to 25 litres will increase Octane levels in your tank by 'one
> unit' thus contradicting the advertising claims!
I 'phoned a bod at Castrol who said that the figure was two units. Millers
said the same of their product but I reckon some graphs/figures would help.
BTW, I have no connection with Castrol but it suits my car and in any case,
Millers VSP is not available in York.
Cheers,
Dave Hill
> Colin
> '67B
>
>
>
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