Even more Sereis 3 troubles

Good afternoon.

Sorry to be pestering about this problem, but i am still drawing blanks.

series 3 2.6 litre straight six. i rebuilt carbureutor, put new set of
points and condensor and the motor is in excellent mechanical condition. it
is getting a good strong spark from each cylinder and the vacuum advance is
working. when motor is revved, timing advances by about 10-15 degrees. but
the problem remains, the manifold is still glowing red hot after about 10
mins of driving at 80ks an hour on flat.

i have played with timing, tried it from about TDC all the way through to 20
degrees BTDC, played with the mixture, all the way from lean as it will go
to just before the setting screw falls out. at settings, the motor runs
reasonably smoothly, but still has the glowing manifolds. the motor is still
staying within it's normal operating range, which is quite cool.

the one last thing i can think of is fuel. it is built to run on leaded fuel
but up til now i have been running it on unleaded without putting any
additive into it. i know i'm probably gonna cop a bit of flak for this, but
i was under the impression that running it on unleaded would simply
accelerate valve wear etc. a friend told me that it can infact cause the
valves to get hotter, thus causing the manifold to get hot.

so my question is thus, will running a motor designed for leaded on unleaded
cause the exhaust manifold to get extremely hot??

if so, i will fork out the extra 10 cents per litre for the premo unleaded.
grumble grumble. but i will putting it on gas soon anyway!!

/thanks in advance.

Sam.

Samuel came up with the following;:

> so my question is thus, will running a motor designed for leaded on
> unleaded cause the exhaust manifold to get extremely hot??

Dunno ...

> if so, i will fork out the extra 10 cents per litre for the premo
> unleaded. grumble grumble. but i will putting it on gas soon anyway!!

.... So why not try that anyway ?

I'd also look at the mixture and any needle jets in the carbs. If the
zorsts are glowing ISTM that it's just as likely to be a mixture problem.
Make sure the air or fuel flow isn't restricted in any way, and check the
back end of the exhaust that there isn't half a ton of concrete, or similar
crud, stuck in the tailpipe.

--
Paul ...
(8(|) Homer Rules ..... Doh !!!
ebay stuff 5220527879 7987515557

"Paul - xxx" <[email protected]> wrote in message
news:[email protected]...
> Samuel came up with the following;:
>
> > so my question is thus, will running a motor designed for leaded on
> > unleaded cause the exhaust manifold to get extremely hot??
>
> Dunno ...
>
> > if so, i will fork out the extra 10 cents per litre for the premo
> > unleaded. grumble grumble. but i will putting it on gas soon anyway!!
>
> ... So why not try that anyway ?
>

I just put half a tank of 98 octane premium into it but there was already
half a tank of the normal petrol in it. i also chucked a load of the
valve-saver stuff in it. i drove this hard up quite a long hill and the
manifold seemed to be glowing less, but there wasn't a great deal of time
for fuel to mix etc. and judging the "glowing-ness" of an exhaust manifold
late at night in the cold and rain when you've just had to turn back from a
weekend away because the bloody cars is causing trouble is a little
subjective and prone to errors.

> I'd also look at the mixture and any needle jets in the carbs. If the
> zorsts are glowing ISTM that it's just as likely to be a mixture problem.
> Make sure the air or fuel flow isn't restricted in any way, and check the
> back end of the exhaust that there isn't half a ton of concrete, or
similar
> crud, stuck in the tailpipe.
>

the side-draught stromberg 175 cd has only one mixture adjustment screw and
i have tried it with mixture set at both extremes with similar results.
fuel-pump works well, and air supply seems to be good. i have also checked
the exhaust and it all seems to be free of obstruction, no bananas or
potatoes up the tail-pipe. i did a lap around the block without the muffler,
for "investigative" purposes of course, and boy does it sound Beefy. i love
it!! almost tempting to leave it off all the time.

Sam.

Sam,

If you want to know if the mixture is right take out a plug and look at
the deposits on it. You want a nice tan colour. I'm sure if you search
there will be pics up somewhere for comparison.

I don't know if you should put premium grade fuel in. I think the
engine was designed/tuned for 2 star (low octane) fuel.

It will either be timing or mixture - and you are right to worry - your
exhaust valves will be history soon.


choo

so Samuel was, like...
> i have played with timing, tried it from about TDC all the way
> through to 20 degrees BTDC,

How are you setting the timing? I'm pretty sure that it should be set to
between 6 and 0 degrees BTDC (depending on model, CR, territory etc) if you
are using the static method, but ISTR that if you use a strobe and
tachometer to set the timing at idle speed (~500rpm) it should be something
like 6 degrees ATDC. Prepared to be shot down if I'm wrong on this.

> the one last thing i can think of is fuel. it is built to run on
> leaded fuel but up til now i have been running it on unleaded without
> putting any additive into it. i know i'm probably gonna cop a bit of
> flak for this, but i was under the impression that running it on
> unleaded would simply accelerate valve wear etc. a friend told me
> that it can infact cause the valves to get hotter, thus causing the
> manifold to get hot.

Never heard of this. The action of lead (or an additive) in the petrol is
to physically cushion the action of the valves hammering against the seats.
It has nothing AFAIK to do with combustion temperature. Again, ICBW.

>
> so my question is thus, will running a motor designed for leaded on
> unleaded cause the exhaust manifold to get extremely hot??

I doubt it.

HTH

--
Rich
==============================
Disco 300 Tdi auto
S2a 88" SW
Tiggrr (V8 trialler)

You know I shall have to take a look at my manifold some time to see if it
is doing that as I run on cheapo unleaded only. I have got to sort out my
own overheating problem eventually as one day that needle is going to go a
little too far over but just have not had the time or the inclination lately


--
Larry
Series 3 rust and holes




"Samuel" <[email protected]> wrote in message
news:[email protected]...
> Good afternoon.
>
> Sorry to be pestering about this problem, but i am still drawing blanks.
>
> series 3 2.6 litre straight six. i rebuilt carbureutor, put new set of
> points and condensor and the motor is in excellent mechanical condition.
it
> is getting a good strong spark from each cylinder and the vacuum advance
is
> working. when motor is revved, timing advances by about 10-15 degrees. but
> the problem remains, the manifold is still glowing red hot after about 10
> mins of driving at 80ks an hour on flat.
>
> i have played with timing, tried it from about TDC all the way through to
20
> degrees BTDC, played with the mixture, all the way from lean as it will go
> to just before the setting screw falls out. at settings, the motor runs
> reasonably smoothly, but still has the glowing manifolds. the motor is
still
> staying within it's normal operating range, which is quite cool.
>
> the one last thing i can think of is fuel. it is built to run on leaded
fuel
> but up til now i have been running it on unleaded without putting any
> additive into it. i know i'm probably gonna cop a bit of flak for this,
but
> i was under the impression that running it on unleaded would simply
> accelerate valve wear etc. a friend told me that it can infact cause the
> valves to get hotter, thus causing the manifold to get hot.
>
> so my question is thus, will running a motor designed for leaded on
unleaded
> cause the exhaust manifold to get extremely hot??
>
> if so, i will fork out the extra 10 cents per litre for the premo unleaded
..
> grumble grumble. but i will putting it on gas soon anyway!!
>
> /thanks in advance.
>
> Sam.
>
>

Richard Brookman wrote:

> so Samuel was, like...
>
>>i have played with timing, tried it from about TDC all the way
>>through to 20 degrees BTDC,
>
>
> How are you setting the timing? I'm pretty sure that it should be set to
> between 6 and 0 degrees BTDC (depending on model, CR, territory etc) if you
> are using the static method, but ISTR that if you use a strobe and
> tachometer to set the timing at idle speed (~500rpm) it should be something
> like 6 degrees ATDC. Prepared to be shot down if I'm wrong on this.
>

Thinking sideways a bit .... have you verified the accuracy of the
timing mark that you are using for TDC? It is possible that someone in
the past has reassembled the parts incorrectly - even fitted wrong
parts. (They might not have used the marks to set the ignition timing
but you wouldn't know that).

Is this a new problem - i.e. did it work before but does no longer? What
changed? If I've picked up the right thread, manifold overheating was
not the original complaint (perhaps it just wasn't mentioned). It seems
that the overheating manifold only appeared after you tried timing
adjustments so that must be the most suspect area.

The suggestion to observe the plugs to check the mixture is a good one.

On Mon, 18 Jul 2005 18:22:18 +0100, "Richard Brookman"
<[email protected]> wrote:

>Never heard of this. The action of lead (or an additive) in the petrol is
>to physically cushion the action of the valves hammering against the seats.
>It has nothing AFAIK to do with combustion temperature. Again, ICBW.

The lead stops the valve seat burning out. So if unleaded is used and
the valve seats are soft the valve sits further into the seat. This
then reduces the valve clearance. So when the valve is hot it
lengthens, with no valve clearance it never seats, so hot burning
gases get into the manifold.

AJH

> the side-draught stromberg 175 cd has only one mixture adjustment screw
and
> i have tried it with mixture set at both extremes with similar results.
>

There must be something wrong with the carburettor if moving the mixture
screw either way has no effect. If you want I can e-mail you the manual
pages on carburettor settings to check.

Have you checked for air leaks around manifold or servo and are the exhaust
valve clearances ok. As others have said, it must be either timing retarded
or weak mixture.

Martin