Technical Weber 26IMB 5 rare Sports Carb

[Toshi 975]

Not something you will see every day or possibly ever.
A few years ago a guy contacted me and said that he had a suspect carb on his car. After a chat he agreed to send it to me for assessment. When I received it I realised 2 things, the spindle was very worn and that it was a Weber 26IMB 5 which I did not know existed. The guy then told me that it came from an Autobianchina Cabriolet that he needed to move. I said that the carb needed to have the spindle rebushed which I offered to do best ut he opted for a rebuilt standard carb that I had ready to go. We did a px deal and this carb has been in my garage ever since.
Decided to work on it today so sorted out a better spindle and rebushed the body so it is now going back together. I had not noticed before but it has the enlarged Venturi size of 22 actually on the casting as opposed to the normal 21.

 

[Vikingsen]

The manual reffering to these 3 Autobianchi's, says they came with th 26imb5 installed:
Bianchina 110/DBA
Bianchina 110/DBA/1 Special
Bianchina Cabriolet

I wish it was mine.

 

[Toshi 975]

The manual reffering to these 3 Autobianchi's, says they came with th 26imb5 installed:
Bianchina 110/DBA
Bianchina 110/DBA/1 Special
Bianchina Cabriolet

I wish it was mine.

I was most surprised when the owner of the car said he was more than happy with a 26IMB 10 rather than stick to the original spec. It has been interesting pulling it apart for inspection. All of the standard 500 carbs share the same specification Weber 26IMB 1,4,6 & 10. The different models have structural improvements. The Weber 26IMB 3 as fitted to the Sports model has the 22mm venturi as opposed to the standard 21mm and a larger main jet , increased from 1.12 to 1.25. This specification is the same on the 26IMB 5.

 

[fiat500]

I was most surprised when the owner of the car said he was more than happy with a 26IMB 10 rather than stick to the original spec. It has been interesting pulling it apart for inspection. All of the standard 500 carbs share the same specification Weber 26IMB 1,4,6 & 10. The different models have structural improvements. The Weber 26IMB 3 as fitted to the Sports model has the 22mm venturi as opposed to the standard 21mm and a larger main jet , increased from 1.12 to 1.25. This specification is the same on the 26IMB 5.

Come on Dave....sell it, sell it, sell it!
Current price of the equivalent 1kg bar of gold from The Royal Mint: £43,770....you could probably give a discount on that.

 

[Vikingsen]

I was most surprised when the owner of the car said he was more than happy with a 26IMB 10 rather than stick to the original spec. It has been interesting pulling it apart for inspection. All of the standard 500 carbs share the same specification Weber 26IMB 1,4,6 & 10. The different models have structural improvements. The Weber 26IMB 3 as fitted to the Sports model has the 22mm venturi as opposed to the standard 21mm and a larger main jet , increased from 1.12 to 1.25. This specification is the same on the 26IMB 5.

The first Fiat 500 Sport had a 26imb2 carb, likewise with the 22mm venturi.

 

[Toshi 975]

The first Fiat 500 Sport had a 26imb2 carb, likewise with the 22mm venturi.

There is no 26IMB 2 shown in any book or manual.

 

[Toshi 975]

Come on Dave....sell it, sell it, sell it!
Current price of the equivalent 1kg bar of gold from The Royal Mint: £43,770....you could probably give a discount on that.

Peter I had already sent the PM but I was going to settle for 1/2kg

 

[Vikingsen]

There is no 26IMB 2 shown in any book or manual.

There are more than one place reffering to: before 1959 it was 26imb2 after it was 26imb3

Like
https://webshop.fiat500126.com/en/sites/339/
or
https://www.cincent.it/scheda-tecnica-fiat-500-sport/

Personally I don't know, I'm just a humble Googler.

 

[Toshi 975]

There are more than one place reffering to: before 1959 it was 26imb2 after it was 26imb3

Like
https://webshop.fiat500126.com/en/sites/339/
or
https://www.cincent.it/scheda-tecnica-fiat-500-sport/

Personally I don't know, I'm just a humble Googler.

Well I stand corrected on that one, never seen that before. Even the original Fiat factory workshop manual makes no reference to a 26IMB 2. Apologies for doubting you.
I did find an original but incomplete Weber 26IMB 1 in all my carbs. The least robust of the range with a couple of weak points but I suspect the basis for the IMB2. The IMB3 may have been based on the IMB4 which was the carb fitted to the 500D. The IMB5 follows the design of the IMB4.
I returned the IMB1 to full working order and got loads of offers for it on eBay from Italy so they are even a shortage item there.

 

[fiat500]

Well I stand corrected on that one, never seen that before. Even the original Fiat factory workshop manual makes no reference to a 26IMB 2. Apologies for doubting you.

True humility....very refreshing. Most often when people are shown to be wrong or mistaken, they waffle over it or just ignore.

That doesn't alter the fact that, Google-free, you are still a font of knowledge learned from a wide experience.

 

[the hobbler]

I have an old "Haynes" workshop manual (cost £2.00p) possibly printed in the mid '70s (no print date on the book---I am going by the fact it gives engine details for the '126' Mk 1, 595cc engine). IT quotes the carb for the 500 Sport as a 26IMB3 with a 22mm choke and a 1.25 main jet. Not surprised that the '2' is not well known about.