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Re: Return of the unleaded thread

To: triumphs@autox.team.net
Subject: Re: Return of the unleaded thread
From: egilk@oslonett.no (Egil Kvaleberg)
Date: Mon, 23 Oct 1995 14:38:08 +0200
Newsgroups: mail.triumphs
Organization: Siving Egil Kvaleberg AS
References: <01HWRWKBHBJ2000459@holly.nene.ac.uk>
In article <01HWRWKBHBJ2000459@holly.nene.ac.uk>,
"Richard Jackson - Network Technician ext. 2570"
 <RICHARD.JACKSON@nene.ac.uk> wrote:
> >With specific respect to Triumph 6-cylinder engines (in my case
> >a Vitesse, head equivalent to a Mk I GT6) has anybody experienced
> >valve recession problems when going over to unleaded?
> 
> >I've started her on premium unleaded with a wee dram of Marvel's
> >Mystery Oil (tee-em) in the hope that this will help provide the
> >missing lubrication.   Do I have much to worry about?  How is
> >Triumph steel at handling unleaded?
> 
> I have been using a mix of unleaded with the occassional dose of lead for
> nearly two years and 40,000 miles, when I did the clutch the other week I
> noticed how easy it was to turn the flywheel by hand, so hopefully in the 
> near future I'll whip the head off and check the state of things in there,
> I don't think it rings causing the lack of compression as it doesn't burn 
> any oil, but it's a Triumph, so who knows.

After approx. the same mileage on very low lead and lead-ersatz petrol,
the exhaust valve seats on my 150bhp 2.5 PI were pretty well burnt, to 
the extent that one exhaust valve har a crack in it. The inlets were
still perfect. 

All info I get from oil companies also tell me that running unleaded
on old-fashioned seats will drastically reduce life. 

My guess is that if you just cruise around town you might not notice
much of a difference, but if you increase exhaust valve temperatures
by extended quick driving, the exhaust valves will fail quickly.
 
I am now having built a new head with hardedend seats as well as
214N valves for good measure. I assume if would be false economy 
not to rebuild to unleaded spec.

There is a rumour that the Lucas injection system needs the lead for
lubrication. I think that this doesn't make sense, because the lead
only has a lubricating effect at very high temperatures. We'll see.

Egil

-- 
Email: egilk@oslonett.no  Voice: +47 22523641/92022780 Fax: +47 22525899
Snail: Egil Kvaleberg, Husebybakken 14A, 0379 Oslo, Norway
URL:   http://www.oslonett.no/home/egilk/
URL:   http://www.oslonett.no/home/egilk/t2000.html

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