Morris Minor Owners Club

I'm confused about the different SU carbs. Is there a reliable way to identify them, beyond measuring the diameter of the outlet, 1.25 in etc?

The one on my 1098 has AUD 13 on a tag on one float lid screw. I've read this can be important, but presumably the tag is often lost. And the carb shows several other similar numbers on various components.

I've just bought (somewhat recklessly) a secondhand 1.25 HS type for parts and I want to know what I've bought when it arrives.

Thanks in advance

If you post a picture of what you have bought that will be most helpful.
There is little difference between the various HS2 carbs. The main differences relate to the needle, the damper spring and the jet.
Some later HS2 carbs have the additional inlet port on the side of the carb to accommodate the sealed breathing system.

Here is a link to the Burlen SU car site:-
https://www.bing.com/ck/a?!&&p=81e62d87 ... 4uY28udWsv

I owned a D reg two door saloon fitted with a carb with the pipe on the side a few years ago.

It was the smoothest, quietest, fastest Minor I have ever driven.

For the earlier carburettors H and HS type, the number e.g 2 in HS2, is the number of eights of an inch above 1 inch. So HS2 is 1 inch + 2/8ths =1.25 inch throttle disc. HS4 is 1 inch plus 4/8ths =1.5 inch.

Later carburettors are the throttle disc diameter in mm e.g HIF38 =38mm throttle disc.

Yes, the tag on the float chamber also tells you what carb it is and what the application was, e.g AUD13 Morris Minor 1098cc.

With the basic HS2 you can change the needle, jet and spring to suit the particular engine.

As Phil says, very late HS2 carbs have an inlet pipe for crankcase breathing. This superseded breathing via PCV valve. The breather inlet can be easily blocked off if not required but it is a good system (also requires tappet chest oil separator "chimney" or later A-series timing chain cover with breather).

Stephen

Thank you all. That's interesting there's not much difference in the HS2s.

I shall post a pic or two when it arrives.

KevinB wrote: ↑Sat May 09, 2026 2:39 pm Thank you all. That's interesting there's not much difference in the HS2s.

I shall post a pic or two when it arrives.

Indeed but they are also handed with float bowl on left or right to suit different applications and as twin carb set ups.

Stephen

svenedin wrote: ↑Sat May 09, 2026 3:44 pm Indeed but they are also handed with float bowl on left or right to suit different applications and as twin carb set ups.

Stephen

Aaah, of course. A very good point. That could catch me out!

It's arrived. The tag says AUD 86.
Here are a couple of photos.

It is for an A-series engine but it's for a Mini 67-68

Float bowl is on the correct side

With the correct jet, needle and spring this should be fine. You'll have to find out what it has fitted at the moment.

One thing I can't see in your pictures is the brass guide tube for the choke cable.


Stephen

Thank you Stephen. That's good to know.
Are the guide tubes standard? I guess I should ask Burlen.

KevinB wrote: ↑Mon May 11, 2026 3:02 pm Thank you Stephen. That's good to know.
Are the guide tubes standard? I guess I should ask Burlen.

They’re standard on carbs designed for the Minor. I don’t know about others.

Stephen

Sorry Stephen, my mistake. I meant available, not standard.

I now have a part number from Burlen, so I have asked if they sell them.

It's called a ferrule and under £2 from Burlen

KevinB wrote: ↑Tue May 12, 2026 2:11 pm It's called a ferrule and under £2 from Burlen

Result!


Stephen

The vent cover appears to be missing from the float chamber.

Don

don58van wrote: ↑Tue May 12, 2026 11:19 pm The vent cover appears to be missing from the float chamber.

Don

Thank you Don. I don't know what a vent cover is? Is a photo available?

KevinB wrote: ↑Thu May 14, 2026 12:01 am

don58van wrote: ↑Tue May 12, 2026 11:19 pm The vent cover appears to be missing from the float chamber.

Don

Thank you Don. I don't know what a vent cover is? Is a photo available?

The vent on the Float Chamber is a small hole just under where the inlet connection is.
There should be a small metal plate clipped over it, presumably to stop dirt getting in and also, should the float stick open and the pump over fill it, then the spill will dribble down the carb rather than squirt out like a water pistol.
It's not uncommon to see them missing on used Carbs on ebay.
I imagine SU will have them, the problem is many of the parts in their shop don't have illustrations....
I clipped these from online images.

As Berni says. The black thing is a Grumpy float bowl heat shield.

Stephen

Thank you both. Yes, I seen them vent covers before, just wasn't sure what they were for.

Burlen sent me a schematic of parts with numbers. It helps and shows that cover as part of a float bowl sundries kit.
Alternatively, maybe something could be easily fabricated from a piece of cardboard etc?

I’d just get the correct part

Stephen