Morris Minor Owners Club

Hi,

I have petrol coming out of the top of the float chamber at random times. I think the the breather pin thingie is getting stuck. Have removed top of float chamber and blown down input pipe and it does seem to be getting stuck, as sometimes the breather valve works and sometimes doesn't. So how do you get the brass pin (that the float is attached to) off. A gentle bit of tapping? Or is there a better way. Thought I would ask the experts before I mess up my carb!

Cheers

Rob

Rob
www.sucarb.co.uk (aka Burlen Fuels ) supply any necessary parts you might want to restore any SU product.
This link pulls up all the parts on an HS2 carb as fitted to a Morris Minor.
http://sucarb.co.uk/carbspec/carburetto ... s/id/1907/
The hinge pin just needs a few gentle taps with a small pin hammer. Before picking up the hammer , try soaking with WD40 , putting into
hot soapy water , very gently twisting with a pair of pliers , nor more than 60 degrees at a time - back and forth. Try that in any combination but the WD40 treatment will start the process of " movement .
There is a breather " hole" in the top of the float lid , covered by a small shield type cover. Poke the dirt out if clogged up.
What you refer to as the " breather valve " is probably the inlet valve and dirt in the fuel sometimes clogs it up. The little tip in the bottom of the valve ( that rests on the hinge float ) should move freely. As the float rises , as petrol comes into the carb from the fuel pump , it shuts off the petrol when full.
If it doesn't move freely either there is still dirt in there or the valve has got worn and needs replacement. The metal end that forms a seal
at the other end of the tip wears a "ridge " after many miles service. You can get a new inlet valve for the carb.
If you want me to spell out the parts numbers , etc. let me know.

Hope this helps your knowledge of the problem. Any clarification / recap come back to us, we don't mind , we all had to learn at some time in the past. In my case several decades ago!
Bob

Thanks Bob,

The small needle does indeed move up and down, but also the brown sleeve it sits in comes out as well. Is this normal? as this bit seems to be getting stuck.
Probably daft question but I'm new to this and not sure if I need to order whole new set.

Thanks

Rob

Rob
The needle is encased in a plastic sheaf ( cylindrical in shape , with 4 flutes ) to centralise it in the valve seat. With several thousand miles under it's belt the petrol would have turned it brown. It should be a " one piece " item. If it has separated then this is not helping a smooth operation of fuel shut off. In itself probably a good indicator of the need to replace.

It's best replacing the needle and seat , as a pair ...or substitute these two items with a Grose Jet ( http://www.moss-europe.co.uk item GAC9201X £7.40 ) plus you'd need their gasket AUC8459A £1.37 ...would you need a new float pin AUC1152 £0.75 ? ).

SUcarbs ( Burlen Fuel ) do a Needle and Seat Kit ,Viton tip , VZX1100 which includes the gasket for £7.50. If you needed it , their pin for the float AUC1152 is 46p.

Tools for removing the brass seat inside the metal float top casting.
It will be " gummed up " with petrol deposits. Turn it upside down and blast it with Plusgas dismantling fluid or WD40 if you don't have Plusgas and leave to soak in.
You'll need a thin walled socket to get down inside to the nut shape to release..
It's a 11/32 " AF ( I use a 1/4" drive ratchet ). If you don't have an imperial socket , try a 9mm socket ( it's a bit loose ) making sure you
get it down right to the bottom , so you don't round off the seat.
Bob

This is the spanner you need to remove the float chamber needle seating and it is well worth the money.
http://sucarb.co.uk/tools-flow-meters/t ... anner.html

G'day all
A word of caution re using a Grose needle and seat. I purchased a new HS4 carby for my blown MM from Midel and it was fitted with a Grose needle and seat to accomodate for the extra fuel consumption. When the dyno man was setting things up he suddenly ran around and switched off the motor. The top of the float chamber was flooded with fuel. Investigation revealed the Grose assembly discharged fuel into the float chamber from holes radially spaced, and one of these holes directed fuel directly at the vent hole in the float chamber cover. My tuning man suggested that this was the problem with the surging I was experiencing - apparently the fuel discharged gathered in such a quantity that it travelled around to the low pressure area of the air filter intake and was sucked into the motor. He obtained a high flow needle and seat wihch discharged fuel downward as a normal needle and seat would do. As I realised that a fire may have started as a result of this, needless to say I went and bought a fire extinguisher on the way home.
Bob

Interesting and very valuable knowledge for those with a larger SU HS4 carb and a non standard blown engine..... always check out the specification and their implications of new parts carefully before assembling. Nice engine bay by the way.

With respect , so as not to frighten Rob ,the original poster , who has a standard Morris Minor SU HS2 carb and engine , he may rest assured that a Grose jet will work perfectly fine. If he choses that option.
Bob

Thanks Bob,

Really comprehensive and easy to understand. Will get on ordering the parts then sort.
Thanks also to Phil and other Bob too.

Cheers

Rob

Bob
I have attached a link showing a HS2 fuel bowl top assembly where it states that it also fits a HS4. If fuel can be discharged from the top vent when using a Grose needle and seat in my HS4, why can it not do the same when a Grose needle and seat is fitted to a HS2? Not wanting to begin a dispute but just my curious nature wanting to learn.
Bob
http://minisport.com.au/su-parts-and-carbies

Bob
I believe I have come up with the answer. I went and searched for the Grose valve removed from my carby. It took an hour to find it and I have attached a pic of it along with a link to SU Midel who supplied the carb. Both needle valves appear to be identical. They built it for my motor after I specified the displacement, blower boost and max. RPM and they decided to fit the SU301 needle valve with a 0.125” port. When looking at the valve pictured and comparing it to the one in the link attached to your post of March 18 at 10:32 AM there is a big difference in the distance from the seat washer face to the discharge holes. I am pretty pi@@ed of with Midel who are supposed to be experts for supplying a carby that discharges fuel from the vent hole. My carby is on the right side of the motor, however had it been on the usual left side in the proximity of the exhaust manifold I’m sure I would have experienced an engine fire. This would have devastated me after designing and building my motor. I will never understand why a needle valve that discharges fuel out sideways instead of downward is used. My high volume replacement valve has been in service since March 2012 without a sign of a problem. I will be enquiring about the details of the replacement valve and will post the detail for members info.
Bob
http://www.sumidel.com/shop/item/grose-type-needle-seat

I believe we are not " comparing apples with apples " ... a Grose Jet and a Grose type jet are not the same thing ...evidenced by comparison of the your posted image with Moss-Europe's Grose jet image.
It is appalling that your suppliers made what could have been a disastrous error. Fortunately it didn't result in personal injury or worse
still. In Europe we are pretty well protected by Consumer Legislation , with Manufacturers having to comply with Industry set Safety requirements and ultimately the product being " fit for purpose " ( i.e. not only does it " fit " the thread ...but it performs efficiently and safely )
A chastening experience for you and fortunately you are alive and well and able to tell the tale. Thank you for sharing the information and experience with us.
Bob