S.U.Carburretor - unusual fault ? :

Looks like my never before troublesome S.U.carburettor has decided to turn around and bite me.
First warning - a strong smell of petrol in the car. On examination it was clear to see petrol flowing from the float chamber.
I thought that if I replaced the float chamber lid unit (complete with float & needle valve ) it would be problem solved.
Wrong ! On further examination the petrol leak was located at the bottom of the float chamber.
My friend and local Mini mechanic Pierre succeeded in opening up and looking at the problem (without removing the carb !!)
Attached to the float botttom is the fuel outlet pipe - made from plastic protected with a spiral wire jacket. This pipe is attached
to the float chamber by way of a brass banjo bolt screwed into the chamber and sealed with a tiny steel washer and a rubber grommet.

The rubber grommet had apparently perished - though it was not possible to view it with the carb still attached to the car.
Our local S.U.CARB agency suggested that I remove the carb & deliver it to them. As some of you will remember - this car's engine was
the subject of a complete (and at the time disappointing) re-build in March of this year - I decided to send the entire car to them for
a complete Carburretor overhaul &/or revamp. I was strongly advised not to attempt to start the car again as a seious engine fire could
easily occur ! So it was transported on the back of a recovery truck this afternoon & delivered one hour later to our local S.U.people.
They have promised that I can collect my restored-to-full health car tomorrow.......watch this space.
David 2010.

It's not unusual; I've seen it a few times. I think it's one of the reasons that the HIF range of SU carbs was designed differently. Fortunately it's not all that difficult to fix either.

O ring size RO2 is a perfect fit! And pennies to buy!, you can remove it all without taking the carb off too.

Nick wrote:O ring size RO2 is a perfect fit! And pennies to buy!, you can remove it all without taking the carb off too.

and best place to get said rubber ring for pennies is......................??

Motor factors etc. sell them in small packs.

Big_Al_Smith wrote:

Nick wrote:O ring size RO2 is a perfect fit! And pennies to buy!, you can remove it all without taking the carb off too.

and best place to get said rubber ring for pennies is......................??

Collected the car back this morning - fault corrected - but as part of a complete o/haul of not only the offending AUD69R, but as the
serial no.suggests, the o/haul of its twin - the AUD69L. S.U.twins are a mixed blessing. They are great when both behave, but when one
of them decides to act up - trouble.It is no coincidence that the top Mini Auto Test drivers in Ireland ( both North & South ) use a single
1.75" S.U. Both of my 1.25" carbs were quite badly worn - probably due to being 47 years old !

Their o/haul included the fitting of 2 new jet assemblies ; 2 new needle valves ; 2 new float kits : 1 cable connector all @ EUR 156.
There was also the small matter of 3.5 hours labour " EUR 75.00 / hour bringing the bill to a "pretty penny".

Happy to report that the car has been re-juvenated - and I should hope so to !
David2010.

Agreed, twins have their advantages (and a set will be going on my GT), but for my daily car it's a HIF44 all the way.

Nick wrote:O ring size RO2 is a perfect fit! And pennies to buy!, you can remove it all without taking the carb off too.

I went to our local motor factors this morning and bought some RO2 O rings.
Then brought my car back to Dublin's S.U.Carb.people to get both carbs synchronised by their S.U.guru (who was on holidays last week).
Whilst there I produced the RO2 O rings purchased earlier.
Their O-ring as fitted to their HS2 (and HS4) S.U. carbs bear very little resemblance to my O-rings.
They are of approximately the same size but whilst my O-rings are of circular cross section - the "official" rings have a square cross
section - that is to say they are flat sided - on each side.
Their verdict " your O-rings not fit for purpose "

Thought I should pass this infomation on - would welcome your comments Nick.
David2010.

Well, I have never had any issues with fitting an 02 o ring! I use them in all my rebuilds.

[url]http://www.minispares.com/product/Classic/Fuel/Carburetors/Spares/AUD2194.aspx?130203&ReturnUrl=/search/classic/carb%20seal.aspx|Back%20to%20search[/url]

70p.

Thing is, petrol attacks some types of rubber, so whatever o-ring you use needs to be petrol grade.

Hi David! Got your letter! Will be in touch soon! Great pic by the way!
Regards,
Nick

Hi Nick
Got your letter on Thursday.
Amazingly - one of the O rings - the biggest one - was completely mashed in the post.
Will keep a small supply of RO2 rings just in case I get a recurrence of the leak problem.
Many thanks for clarifying the O ring mystery.

My Cooper Rally Car is an original Mk.1 998cc - however it was discovered during its engine re-build last February that the bores
were already 40 thou oversize. Thus giving making it a 1071cc - but I'm afraid its still not an "S".
Best wishes
David2010.