Specifications 24 and 28mm carburettors
24 and 28mm carburettors are used in Fiat 500’s and Fiat 126’s. These carburettors are used on 600 and 650cc engines. We have tried to make a complete list of all types with their specifications. You can always comment on this page if you are missing something or in case of any mistakes.
24IMB1 #
| Used on | 500R 594cc 1973 126A 5000 |
| Main | 1.25 |
| Stationair | 0.50 |
| Emulsion | F8 |
| Air correct | 2.25 |
| Starter | F5/90 |
| Needle | 1.25 |
| Venturi | 4-18 |
28IMB1-100 #
| Used on | Fiat 500R / Fiat 126 594cc until 11-1974 |
| Main | 1.25 |
| Stationair | 0.45 |
| Emulsion | F8 |
| Air correct | 2.15 |
| Starter | 0.90 |
| Needle | 1.25 |
| Venturi | 4-23 |
Extra info #
- Mixing screw needs spring, saucer and underlying o-ring
- On carburettor Made in Italy
- Top cover often only Weber Logo
Pictures #
28IMB3-100 #
| Used on | Fiat 126 600cc after 11-1974 (Europe 75) |
| Main | 1.25 |
| Stationair | 0.45 |
| Emulsion | F8 |
| Air correct | 2.15 |
| Starter | 0.90 |
| Needle | 1.25 |
| Venturi | 4-23 |
Extra info #
- Mixing screw internal in sleeve and internal o-ring
28IMB3-250 #
| Used on | Fiat 126 594cc 1976 Europe / Fiat 126P 600cc |
| Main | 1.15 |
| Stationair | 0.45 |
| Emulsion | F8 |
| Air correct | 2.15 |
| Starter | 0.90 |
| Needle | 1.25 |
| Venturi | 4-23 |
Extra info #
- Mixing screw internal in sleeve and internal o-ring
- On carburettor Made in Italy, also on top cover
Pictures #
28IMB4-250 #
| Used on | Fiat 126 650cc 1976 (Germany, square head) |
| Main | 1.25 |
| Stationair | 0.45 |
| Emulsion | |
| Air correct | 220 |
| Starter | 0.90 |
| Needle | |
| Venturi | 4-23 |
Extra info #
- Throttle valve has only 1 seal
Pictures #
28IMB5-250 #
| Used on | Fiat 126 1977 until 05-1985 650cc Fiat 4381128 |
| Main | 115 |
| Stationair | 0.50 |
| Emulsion | F8 |
| Air correct | 190 |
| Starter | F5/90 |
| Needle | 1.25 |
| Venturi | 4-23 |
| Air bleed | 140 |
Extra info #
- Mixing screw internal sleeve and internal o-ring
- Throttle shaft double plastic seals
- It only says Weber on top cover Made in Poland.
- Sometimes also no ‘Made in …’ on top cover
- Many sold afterwards in aftermarket as spares
Pictures #
Remarks #
- The later spare aftermarker carburettors no longer had a fuel filter and cover
- Made in Italy is also no longer on them
28IMB10-250 #
| Used on | Fiat 126 650cc from 1985 (126A1 076) (FOS Weber) |
| Main | 115 |
| Stationair | 0.45 |
| Emulsion | F8 |
| Air correct | 195 |
| Starter | F5/90 |
| Needle | 1.25 |
| Venturi | 4-23 |
Extra info #
- Mixing screw internal sleeve and internal o-ring
- Throttle shaft double plastic seals
- Manufacturer FOS (no Weber logo)
- On lid Licencja Weber Made in Poland
Pictures #
28IMB12-250 #
| Used on | Fiat 126 Nuova 652cc from 05-1985 (FOS Weber) |
| Main | 115 |
| Stationair | 0.50 |
| Emulsion | F8 |
| Air correct | 195 |
| Starter | F5/90 |
| Needle | 1.25 |
| Venturi | 4.5-23 |
| Air bleed | 140 |
Extra info #
- Mixing screw internal sleeve and internal o-ring
- Throttle shaft double plastic seals
Pictures #
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Updated on 2024-09-05