7 replies to this topic

[Clip]

I can get hold of these early 1 1/2 twin SUs that were bought years ago and never used. But are they worth buying and using, or should I go for a later type? 

Attached Files

•  IMG_0802.jpeg   46.29K   5 downloads
•  IMG_0801.jpeg   41.34K   5 downloads

Edited by Clip, 03 February 2024 - 11:12 AM.

[timmy850]

If they are a good matched pair of H4 carbs and have the right bits for a mini they are a great choice for a Mk1 if you want it to look “of the period”. They are about the same in performance as the later HS4. As usual the simplest choice is a single HIF44

The twin H4 were an option from BMC special tuning for racing as you had to keep the standard manifold, but the H4 carbs bolt up to the same stud pattern as the HS2

The fuel bowls should be part number 4814 and 4815 to be the larger 30 degree bowls

Your set appear to have the right choke linkage for a special tuning set. What are the numbers stamped on the tags on the top of the fuel bowls?

Edited by timmy850, 03 February 2024 - 09:18 AM.

[johnR]

They look quite small for 11/2" are you sure they're H4?

[Clip]

Just added another pic if them.
Owner said definitely 1 1/2, but I don’t have them with me. I’ll have to get onto the owner to get the tag numbers Tim.

These will be used on my 1100 that has mild cam and some headwork and HS6. It’s running very rich on cylinders 2 & 3 around town, fine on faster runs though. I think the twin carbs will help with this issue. 

Edited by Clip, 03 February 2024 - 11:19 AM.

[timmy850]

The dashpots have 3 screws, so they are 1.5”

I haven’t rebuilt and used my set yet, they are much more complex than the HS carbs in terms of gaskets and seals. They are 1940’s tech

[Lplus]

Just added another pic if them.
Owner said definitely 1 1/2, but I don’t have them with me. I’ll have to get onto the owner to get the tag numbers Tim.

These will be used on my 1100 that has mild cam and some headwork and HS6. It’s running very rich on cylinders 2 & 3 around town, fine on faster runs though. I think the twin carbs will help with this issue. 

They will work, but they still might be a bit much for that engine.  According to my SU parts catalogue Downton once did a conversion using H4s, though I'm not sure what that entailed in terms of cam/head etc.

 

I suppose it also depends how much the owner wants for them.

[Clip]

 

I suppose it also depends how much the owner wants for them.

 

How much do you think they would be worth?

[timmy850]

A genuine Special Tuning set would be somewhere around £400 in the UK in need of rebuild. They are a bit less valuable in Aus as not many mini people know about them. The 4814 fuel bowl is very hard to find used and new they are £145 + tax

Eg
https://www.ebay.co....tm/126306217724