Petrol for 1970 Suffolk Punch Lawnmower
Brian coddington
Can I now use 4 star on a 30 year old machine?
Some time ago I read of possible problems to valves due to accumulated
carbon deposits.
Any advice is welcome.
--
Brian Coddington
gardenlen
i repaired mowers for a long time i never recommended super or leaded
fuel for mower engines nor did the manufacturers. in those days it was
standard or low octane fuel nowadays it's un-leaded as i do now in my
machines. they are a low compression motor and don't need high octane
fuel.
len
--
happy gardening
'it works for me it could work for you'
<http://members.optushome.com.au/gardenlen/index1.htm>
"old age and treachery will overcome youth and skill"
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Before you buy.
Nick Maclaren
J@home <J...@oaknet.freeserve.co.uk> wrote:
>On Thu, 29 Jun 2000 16:05:12 +0100, Brian coddington
><Br...@coddington.demon.co.uk> wrote:
>
>>My supply of leaded petrol is almost exhausted.
>>
>>Can I now use 4 star on a 30 year old machine?
>>
>>Some time ago I read of possible problems to valves due to accumulated
>>carbon deposits.
>>
>>Any advice is welcome.
>
>to compensate for the loss of lead (or whatever)? I'm sure
>I've seen this at my local petrol station.
Probably. You can also buy preserving sugar, at twice the price of
granulated. What the suckers - sorry, buyers - don't realise is
that the reason that old recipes called for preserving sugar is
that is was cheaper than the purer loaf sugar, and the purity of
the latter was not needed. Granulated sugar is cheaper and purer
than either, and will do both jobs. Modern preserving sugar is
granulated sugar with added nonsense, and a 100% markup.
The purpose of adding lead was to reduce 'knock' - i.e. to increase
the octane rating - and it used to be difficult to produce the
higher octane ratings without lead. I don't know if one star (yes,
really) had lead, but two star certainly did. And, in general,
you can almost always use a higher octane rating petrol instead of
a lower one.
Current standard unleaded petrol is 3-4 star as I recall, and so
is quite adequate for any lawnmower that I have ever heard of.
Most were quite happy with two star.
Regards,
Nick Maclaren,
University of Cambridge Computing Service,
New Museums Site, Pembroke Street, Cambridge CB2 3QG, England.
Email: nm...@cam.ac.uk
Tel.: +44 1223 334761 Fax: +44 1223 334679
Jack
"Nick Maclaren" <nm...@cus.cam.ac.uk> wrote
news:8jgcld$au8$1...@pegasus.csx.cam.ac.uk...
> Probably. You can also buy preserving sugar, at twice the price of >
granulated. What the suckers - sorry, buyers - don't realise is
> that the reason that old recipes called for preserving sugar is
> that is was cheaper than the purer loaf sugar, and the purity of
> the latter was not needed. Granulated sugar is cheaper and purer >
than either, and will do both jobs. Modern preserving sugar is >
granulated sugar with added nonsense, and a 100% markup.
.............???
> The purpose of adding lead was to reduce 'knock' - i.e. to increase >
the octane rating - and it used to be difficult to produce the > higher
octane ratings without lead. I don't know if one star (yes, > really)
had lead, but two star certainly did. And, in general, > you can almost
always use a higher octane rating petrol instead of > a lower one.
For comparison, LPG contains zero lead and has an octane rating well
over 100 = ***** (but it atomizes well and is clean).
I have always been told that lead also had a lubricating effect on
valves in 4-stroke engines, and more importantly a hardening effect with
lead embedding itself in between the steel molecules. Once there, the
embedded lead will last a long time thus preventing premature overhauls
hence offering environmental gain.
4-stroke engines without stellite valve seats had to be run in on leaded
petrol to harden the seats, after which LPG could be used with
occasional use of petrol. Today's engines all have stellite valve seats
because of the forced ban on lead in petrol.
As far as the quality and properties of unleaded petrol are concerned, I
am not very impressed with using it in automobile and older lawnmower
engines. Lead replacement petrol is in my experience even worse. In all
present petrol type fuels, lead has been replaced by some v e r y
nasty chemical substances the effects of which on health and the
environment cannot be predicted.
> Current standard unleaded petrol is 3-4 star as I recall, and so
> is quite adequate for any lawnmower that I have ever heard of.
> Most were quite happy with two star.
As far as I know most lawnmower engine manufacturers recommend the use
of unleaded (95 octane rating) in older engines. Petrol with higher
octane ratings may require a different igniton timing and/or may lead to
difficult cold starting.
Jack
"Jack" <JRusse...@skynet.be> wrote
news:8jgim8$kre$2...@news1.skynet.be...
>
It should be remembered that lead was taken out of petrol to enable the
use of exhaust gas catalytic converters. These converters are only
operational if their surface area is not coated with lead.
The choice for catalytic converters hence for lead-free petrol was made
on (company) political grounds, not primarily on environmental grounds
and certainly not on combustion technological grounds.