Plugs

Hi Stina,

I have not come across any potential problems when overhauling my carburettors where the needle valves are involved. I have removed them while fitting a new seal kit, but the valves themselves are still the 1974 items, replacement has never been necessary. I have found floats to be faulty in terms of taking on fuel, so one or both required replacing. The little drip of fuel from the overflow when the engine is hot is not an issue, fuel vapour condensing nothing more. I have noticed the same from mine, having overhauled my carbs in 2007 prior to the 4.6 going in. The engine now has now covered 48,000 Miles since then and the occasional little fuel drips have never been cause for concern.

Ron.
 
Hi guys . Had a day on my own . the old man gone camping with his son . ( It's raining as i type :D ) Fitted new fuel filter and needle valves to both carbs . Ticks over sweet , test run tomorrow . We shall see ! The needle valves i removed had a small spring that buts uo to the tab on the float . The ones supplied in the kit were solid . I went ahead any way as no time to wait for a reply from an expert . Set the float levels , no drips from over flow . Is it just a newer / modified part ?
 
Went to see a mate today . About 30 mile round trip , Ran lovely , used just over a gallon of juice at a guess . :D
 
Hello
Could anyone tell me what gauge the spark plugs have to be - thanks :)
Also how much oil to put in dion tube - :)
 
kells41 said:
Hello
Could anyone tell me what gauge the spark plugs have to be - thanks :)
Click to expand...

If you mean the gap, the standard setting is 25 thou, but you may want to open that up a bit if you're running electronic ignition.

kells41 said:
Also how much oil to put in dion tube - :)
Click to expand...

The recommended amount is 1/3 pt from empty, but as there's no way of knowing what's in there already, or draining it to start again, it's really a case of educated guesswork, so an amount of up to 1/3 pt is about all you can say.
 
Hi guys .
Need more ideas . As i said earlier she ran lovely yesterday on a run of about 30 miles . After spending Saturday renewing the fuel filter and the needle valves in the float chambers .
This afternoon i took her to do the shopping and on the way back it was running rubbish . By the time i got home had a job to pull herself along . It did seem to pick up momentarily if i pulled the choke out .
To recap in the last 1000 miles it's had new electronic ignition , coil , cap , plugs .
In the last 100 miles rebuilt fuel pump , needle valves in carbs , new fuel filter .
Checked the timing again when i'd unloaded the shopping still spot on .
I cant understand how it ran so nice yesterday now it wont .
running out of ideas .
Help !
Ps . Just had a couple more thoughts . It revs out clean in neutral , only playing up under load .
I put fuel in it while shopping , it was bad on the way home ! (99 octane )
 
Hi Stina,

Seeing the engine picked up momentarily upon pulling the choke out, that suggests that the mixture prior to that moment was way too lean. The distinct lack of power points to fuel vapourisation to me from what you have said thus far. I am assuming that when this happened the tone of the engine totally changed? Have you insulated the fuel line from where it runs from the reserve tap to where it joins the fuel pump?

Ron.
 
I know PAE likes the 99 octane tesco fuel, but i also have a friend with an alpina B3 which actually wont even start with it in the tank... If immediate investigations reveal nothing the fuel may be something to look at.

Rich.
 
SydneyRoverP6B said:
Hi Stina,

Seeing the engine picked up momentarily upon pulling the choke out, that suggests that the mixture prior to that moment was way too lean. The distinct lack of power points to fuel vapourisation to me from what you have said thus far.
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If it was fuel vapourisation, then why would pulling the choke out give an improvement? If the petrol has vapourised there's none there in the first place, so none extra when the choke is out. What was the ambient temperature at the time?
On way out drove fine, bought petrol, then drove back, and it ran like cr*p. I think that's where I'd start looking.
 
harveyp6 wrote,...
If it was fuel vapourisation, then why would pulling the choke out give an improvement?
Click to expand...

A momentary improvement as Stina indicated.

On way out drove fine, bought petrol, then drove back, and it ran like cr*p. I think that's where I'd start looking
Click to expand...
A range of possiblities not least of all as I have said on many an occasion, the fuel is at the heart of the problem.

Ron.
 
Mmmm. In my experience this sort of fault only really gets solved once it develops to be consistent enough that you can find the fault whilst you're under the bonnet. The signs are pointing to fuel though. I'd sort of be inclined to have a look at a few things that might give you starvation (not vapouristion, Harvey - I agree with you). So go through all the pipe joins between the tank and the pump looking for signs of distress that might allow the pump to suck air. Then there's the O ring in the reserve tap and finally pulling the tank pick up/float level to see if there is any rubbish round the tank pickup.

Actually, there's one further thing you could try next time it misbehaves - pull the reserve out so that you are using the other set of pipework between tank and reserve tap (on the front bulkhead in the vicinity of brake master cylinder) and also the other stand pipe in the tank.

Chris
 
Hi guys thanks for the replies and ideas , i'm stuck on this one it's driving me mad and i'm loosing confidence to take it too far from home . AS you say Chris it needs to be more of a consistent problem for me to get to the bottom of it .
I don't think it was anywhere near hot enough to be vaporisation , it was only around 16 degrees yesterday and on much hotter days it's given no problems even in traffic . If the mixture was too weak it wouldn't of ran so well before when i took it for a 30 mile run ?
Chris i've never touched the fuel reserve tap as i don't know the condition of the O ring within , and don't want to risk it leaking . I do have the correct O ring here . Maybe i need to fit that , Was putting it off as it sounds like a pig of a job ?
When i rebuilt the fuel pump last week i left the original valves in as i had the bigger ones . could they be cause for concern ?
 
stina wrote,...
don't think it was anywhere near hot enough to be vaporisation , it was only around 16 degrees yesterday and on much hotter days it's given no problems even in traffic
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Hi Stina,

Ambient temperature cannot always be relied upon to rule vapourisation out, as an example, back in 1991 my Rover suffered from the dreaded vapourisation during June,..which is Winter here, the ambient temp was only 9 degrees C. Equally I have been in traffic when the ambient temperature was over 36 degrees C and no hint of trouble at all. The only common denominator in my case was the fuel, both leaded and in later years unleaded.

When mine was giving trouble I drained the tank, checked all the lines, fitted a new 'O' ring in the reserve tap, rebuilt the cabs, changed the fuel filter, rebuilt the mech pump, added an OEM Rover asbestos sheath around the fuel line between the pump and the reserve tap, sadly all to no avail. Fitting an electric fuel pump won't cure the problem in terms of raising the fuel vapour point, but it will keep you moving and the hesistation and poor running will disappear.

In the 20 years since I fitted the electic pump in series with the mechanical unit, the need to switch it on has been few and far between, sitting in 38 degree C traffic, no problem, no vapourisation. If you do all you can to minimise the possiblity of problems, then at least you have a back up for those times when the fuel chemistry changes, such as the change over from Summer to Winter fuel and visa versa.

Of course I speak from the sitution as it applies in Australia. Different fuel and a different climate in the U.K may see variations and a possibly a different solution.

Ron.
 
hi Stina

I guess the pump valves sould be a problem, worth eliminating as they are easy to fit. I agree the reserve O ring is a pig of a job - as I was writing it I thought easy to say not so easy to do!

Just to eliminate the possibility of vapourisation, now that Ron has raised it, have you checked the coolant flow from the carburettor tower on the inlet manifold? If that's OK I doubt you'll have a problem in the UK.

I think my next plan of action would be to keep driving until this tank of fuel is near empty. If you manage to tie down the fault in the meantime, all well and good. If not, try the reserve tap when you're nearly empty - they rarely leak on reserve if they are not leaking on main. Once empty, I think I would have the tank level switch assenbly out on the grounds that is a reasonably easy job to do. It is possible the plastic gauze has collapsed onto the outlet pipe. I have a spare pump set in the garage. I'm fairly sure it is large valve - I'll pm you when I've had a look.

Chris
 
Hi all . Latest update . Only had an hour to fiddle today . Checked for any obvious leakage , and had a look at the fuel reserve tap just to get familiar with where it is , what it looks like .
I started it up ( on the button ) and let it warm up while watching the level in the fuel filter . It was empty to start with and filled within half a minute or so . It ticked over smooth and responded to a blip of the throttle .
As it was warming up the level in the filter dropped and their were air bubbles coming up from the bottom of the filter .
Decided to see what happened driving it round the block . On the first run it ran but not very well , was trying to pick up but wouldn't . Took it back home and had another look at the filter , the level was low , just visible .
Tried it round the block again and give it a bit of a boot full . It would only accelerate with full choke , then cut out completely . After a while it started on full choke and i limped it home on full choke , Back in the garage it would only tick over on full choke . Had to leave it alone at that stage , no time left .
It wasn't so much misfiring as such , more needing fuel .
Questions !
: Is this all related to the air bubbles in the filter ( i ask because my moggy ran with the filter never full for 5 years )
: Also if air is getting in somewhere i cant see or smell fuel escaping !
: If i still have a fuel pump problem why would pulling the choke out make a difference ? If it's not pumping fuel up then their is none there .
: This has all got worse since fitting a new fuel filter and needle valves on Saturday , But it ran faultlessly for 30 miles on Sunday .
I'm lost with this one as you can probably guess !
Ideas , help please i need the car this Sunday if poss .
Can devote couple of afternoons to it this week
Thanks .
Stina
 
when you pull the choke you enrichen the fuel i.e allow more to get into the carb.

It is easier with the old HS6 with a seperate bowl to work this one out as you can see the jet drop.the fuel in the bowl is level with the fuel in the jet. when it drops the jet is lower so the fuel flows through it oppose to being drawn up in a vapour.

It looks like you're getting there, bubbles in the fuel filter and low level are telling you something.
 
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