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Alexander hoar
Yet to post message
Username: plumber

Post Number: 1
Registered: 4-2016
Posted on Tuesday, 10 May, 2016 - 21:12:   Edit PostDelete PostView Post/Check IP

Hello
I have a silver shadow 2
I have been having trouble with rough idle
so I decided to check the plugs .
Thery were heavily carbon up
I only change them about 6 months ago
Would this indicate the mixture too rich or faulty
weakener solenoild

Thanks for any help
Alec
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 1523
Registered: 6-2006
Posted on Tuesday, 10 May, 2016 - 21:16:   Edit PostDelete PostView Post/Check IP

Hi Alec,

Can you post pictures of them?
Are they all the same?
Have you being using the car for motorway. Local journeys. Running it stationary?

Cheers, Paul.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1000
Registered: 9-2004
Posted on Tuesday, 10 May, 2016 - 22:01:   Edit PostDelete PostView Post/Check IP

Hello, do you have any blue smoke on the overrun, down hills etc.
If so this would point to worn piston rings or more common fault of inlet valve seals.
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Alexander hoar
New User
Username: plumber

Post Number: 2
Registered: 4-2016
Posted on Tuesday, 10 May, 2016 - 22:07:   Edit PostDelete PostView Post/Check IP

Hello Paul

Thanks for the reply
Unfortunately I've clean them up now

No not all were sootted up its mainly A1,A2,A3, A4
I'ts mainly been running in stationary
Would an over rich mixture ie the jet height too
low in the carb cause the sooting

Thanks Alec
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Alexander hoar
New User
Username: plumber

Post Number: 3
Registered: 4-2016
Posted on Tuesday, 10 May, 2016 - 22:15:   Edit PostDelete PostView Post/Check IP

Hello Patrick

No blue smoke on runs
It's had the problem for a while and in the past I've either cleaned the plugs or changed them

The plugs seem to constantly build up with soot over a short period of time then the car's idle seems more lumpy

Thanks Alec
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 1524
Registered: 6-2006
Posted on Tuesday, 10 May, 2016 - 22:16:   Edit PostDelete PostView Post/Check IP

Running stationary is never good for these old cars.

The plugs listed are fed from different carbs so probably not just a mixture thing.

Until the car is driven 'properly' and in normal use it's impossible to know where you are going with it.

New plugs and some nice drives and see what happens to them then.
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Alexander hoar
New User
Username: plumber

Post Number: 4
Registered: 4-2016
Posted on Wednesday, 11 May, 2016 - 04:25:   Edit PostDelete PostView Post/Check IP

Thanks Paul

My mistake with the plugs old age has set in

It was all the plugs in A bank

The reason for asking about the jet height was my son
adjusted the mixture with a colour tune spark plug a while back and the jet seems low ?

Its the right hand carb looking from the drivers seat
Which as I understand feeds Those plugs

So I was trying to work out if the jet was too low and running
rich was cause sooting on the plugs

I will get some new plugs and give her a day out
Thanks Alec
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 1525
Registered: 6-2006
Posted on Wednesday, 11 May, 2016 - 04:32:   Edit PostDelete PostView Post/Check IP

A1 B2 B3 A4

B1 A2 A3 B4

are how the carbs feed the cylinders.

Cheers, Paul.
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Alexander hoar
New User
Username: plumber

Post Number: 5
Registered: 4-2016
Posted on Wednesday, 11 May, 2016 - 07:12:   Edit PostDelete PostView Post/Check IP

Thanks Paul

As you say it can't just be mixture then

So each carb feeds two plugs from Bank A and B
and as all the plugs in bank A were sooty it can't simply be a mixture problem

I'll take it out for a run with some new plugs

Thanks again Alec
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David Gore
Moderator
Username: david_gore

Post Number: 2038
Registered: 4-2003
Posted on Wednesday, 11 May, 2016 - 08:35:   Edit PostDelete PostView Post/Check IP

Alexander,

It is time to resurrect my "happy weekend" tune up for R-R V8 engines that have spent too much time on short trips and/or idling in stop/start city traffic.

This procedure involves the following:

1. Select a country holiday resort at least 400Km [250 miles] linked by a highway/motorway to your home where you can maintain continuous speeds in excess of 100Km/hr [60mph].

2. Book at least 1 night's accommodation

3. Time your travel to be undertaken as soon as possible after a scheduled engine oil change and spark plug replacement. Drive continuously to and from your destination. Enjoy your time there appropriately.

4. You will notice some changes in engine performance as you get closer to your destination - the engine will be smoother and more responsive.

5. Further improvement should become evident on the return trip.

6. Try to take the car on a long trip [i.e. at least two hours continuous high speed driving] every few months to keep the engine responsive.

This is my version of the traditional "Italian tune up" which I consider to be more appropriate for a R-R/B custodian .
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Bob Reynolds
Grand Master
Username: bobreynolds

Post Number: 389
Registered: 8-2012
Posted on Wednesday, 11 May, 2016 - 19:00:   Edit PostDelete PostView Post/Check IP

It could still be the mixture. Surely your son adjusted both carbs and not just one?

Perhaps he didn't realise which carb fed which cylinder, as it's not obvious.

Colourtune is usually quite accurate, but it can only show you the mixture at idling speed - not when running. I find it a lot more accurate than relying on the lifting pin and listening for a rise in revs.
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Alexander
New User
Username: plumber

Post Number: 6
Registered: 4-2016
Posted on Friday, 13 May, 2016 - 10:28:   Edit PostDelete PostView Post/Check IP

Hello
David that sounds like a very good idea

Hello Bob
Yes he adjusted both carb jets
He did say that they seemed a bit low .When you start he set them level with the bridge and then 1/4 turn to lower them as a starting point
Is there a height you should expect the jet to be set at ? so you would know outside this height you would know it's going to run a bit rich or lean

Thanks Alec
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Bob Reynolds
Grand Master
Username: bobreynolds

Post Number: 391
Registered: 8-2012
Posted on Friday, 13 May, 2016 - 16:31:   Edit PostDelete PostView Post/Check IP

The Shadow1 manual says to lower them 2 turns as a starting point. (Page k20)

1/4 of a turn would be much too lean and I am surprised the engine would run at that setting.

The Shadow2 manual says to lower the jet 3.05mm. That seems about the same as 2 turns. (Page k5-29)
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 1528
Registered: 6-2006
Posted on Friday, 13 May, 2016 - 18:23:   Edit PostDelete PostView Post/Check IP

You really need to check the plugs after a run.

Don't go by measurements except both sides are usually the same.

The jet is mounted on a bimetallic strip which adjusts it's height to compensate for hot or cold petrol. How the engine idles is the most important test.

When you start a car the plugs will soot up. When you drive it the soot gets burnt off.

Every carb RR will soot up the plugs if just run in a garage . . unless you run it up to temperature and then at over 2000 rpm for at least 10 mins .

That may keep your plugs clean but I would not recommend doing it in practice.

Take her for a drive and check the idle on return. Then check the plugs once cooled down.

If they are black and sooty then , you may have a problem.

Enjoy the drives :-)
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Alexander
New User
Username: plumber

Post Number: 7
Registered: 4-2016
Posted on Friday, 13 May, 2016 - 23:36:   Edit PostDelete PostView Post/Check IP

Thanks Paul

It's time to take her out on that maiden voyage


Thanks Bob

I will tell my son it's two turns he is normally ok at reading the manual but does have a habit of speed reading ie only reading what he wants

Thanks Alec

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