Float chamber needle and seat

[M25VAN]

Just replaced these as petrol was overflowing the float chamber. I took the parts out of an SU Kit but noticed there was no gasket for the seat where it screws into the float chamber lid. There wasn't one on the old seat I replaced either and I don't see one listed on the usual spares sites. Should there be one and if so does anybody know what size?
The float chamber is now flooding over the top again. I thought I'd fixed the problem after a few days/250 miles of motoring with no flooding. I shall try adjusting the float but for carbs with a plastic float the manual mentions adjusting by means of such a gasket/washer under the seat.
Finally anyone tried one of the Grose jets (with the ball valve) as they are about the same price?
If anyone knows the size of the gasket I will get some off of ebay.......

[philthehill]

I have just stripped a Minor H2 carb No gasket/seal under the float valve and no gasket/seal in a new overhaul kit. Have been on Burlen (SU) web site and there does not appear to be a gasket/seal under the float valve for either H2 or HS2.
This may seem like a stupid question but have you fitted the valve the right way up (sharp end into the valve)?
See
http://sucarb.co.uk/technical-hs-type-c ... djustments

for setting float level. If it is not a H2/HS2 see the above link for your carb details can be found elsewhere on their web site. I have always very carefully bent the pivot lever attached to the top of the float chamber (including those fitted with plastic floats i.e. HS2) to get the right float level. Never had to fit spacing washers. Even with the twin 45 Webers fitted to my Minor to get the correct float level I just carefully bend the float pivot lever.

[M25VAN]

Yes, in the right way up. Just seems odd that has been working OK for a few days. The float I have has is plastic and has no adjustment. Instead of bending the float up and down I think you have to adjust the height of the needle seating via washers.
Looks like I may have to dig out a spare metal float.

[philthehill]

No mention of adjusting the float level by fitting or taking away washers on the Burlen web site. As I said I have always just bent the lever arm and it does the job. Has your plastic float become punctured? Shake it and see if you can hear any petrol splashing about inside it. Also put the float in some warm water and see if any bubbles come out of it. Punctured plastic floats are a known problem. Burlen now supply 'Stayup' (Trade Mark) floats to alleviate the problem of punctured floats.

[bmcecosse]

There is never any need to adjust the level of the plastic float - it IS right. The Grose valves - some swear by them - some swear at them. My mate bought them for his MGB and had endless problems with them... What fuel pump are you using? Os there perhaps a wee bit of dirt in the float valve?

[M25VAN]

Thanks guys. I have a mechanical pump fitted, been in for years. Can they suddenly deliver at too much pressure? Repairs are a bit difficult at the moment (along with posting replies) as I am a long way from home. Have swapped the chamber lid off an old working spare carb lunchtime and that isn't leaking at the moment.
Problem showed up with bad idle at end of journey. Popped the bonnet and the fuel was running out of the top of the chamber. Turned off the engine but fuel still ran out for a few seconds, I guess that was due to pressure.
I have a spare pump with me so will swap that in desperation if problem persists.

[philthehill]

I agree that you should not have to adjust the plastic float but I have had to do so on numerous occasions even with new floats straight out of the box. It should not be assumed that just because it is new it is correct. The float level needs to be checked against manufactures specification before final assembly.

[M25VAN]

Has your plastic float become punctured? Shake it and see if you can hear any petrol splashing about inside it. Also put the float in some warm water and see if any bubbles come out of it. Punctured plastic floats are a known problem. Burlen now supply 'Stayup' (Trade Mark) floats) to alleviate the problem of punctured floats.

Nice tip, I will try the hot water trick. I think the float may have had a "slow puncture". Looked ok when I put the new needle in but will check when back home. It did look to sit a bit high as if it needed some adjustment. Swapped out float etc. is not leaking so far. Will investigate a stayup float, one less potential problem! Just glad I decided to put the spare carb in. It is a policy that I adopt now after I put in news parts. Take another working spare incase of faulty new part/poor workmanship/disturbance related new problem.

[bmcecosse]

Good idea...

[M25VAN]

Right, had the float off and in a cup of hot water. There were about half a dozen bubbles that appeared around the join in the float. Couldn't detect anything in the float though. Pivot pin was very badly worn and the float was loose on this. I guess this combination of factors and the fact the float looked like it sat too high when in the chamber must have caused the problem. Just replacing the needle valve and seat did nothing to cure this and so the problem reappeared, albeit after a while. Only swapping out with another float and chamber lid has solved the problem.
I won't bother with one of those grose jet thingies and just get one of those stay up floats or some fibre washers to push that current plastic float a bit further down as it sat high as well.