Idle jet (U 1.8) for Solex carburettor. Porsche 356 / 911

Idle jet (calibration U 1.8) is designed for Solex 40 PII-4 carburettors in Porsche 356B/C and 912 models. this jet is engineered to precisely replicate the original Porsche part’s flow calibration (“U 1.8”), dimensions, and functionality. It installs directly without modification, restoring smooth idle quality and consistent fuel metering for authentic performance.
Sold each, 2 required per engine.

Fits:
Porsche 912 1965 - 1968 (Engine code: 616/36/37) 
* for Carburettor SOLEX-40 PII-4

Porsche 356B 1600 S90  1960 - 1962 
Porsche 356C SC  1964 - 1965
* for Carburettor SOLEX-40 PII-4/44 PII-4

Diagram ref no 34

•  Position: Carburettor – idle fuel circuit
•  Function: Controls idle fuel flow for stable low-speed engine operation
•  Precision-calibrated to match the factory specification (“U 1.8”) for stable idle fuel delivery.
•  Direct-fit OE geometry ensures correct installation in Solex 40 PII-4 carburettors without adjustment.
•  Optimized performance for reliable starts, smooth idling, and accurate throttle response in classic Porsche engines.
•  Ideal for restorations, tuning, or routine maintenance where drivability and period-correct operation are key.

Over time, idle jets can become clogged, worn, or corroded, affecting the carburettor’s ability to meter fuel correctly at low speeds.
Common symptoms of a failing or blocked idle jet include:
• Rough or uneven idling Hard starting when cold
• Hesitation or flat spots on throttle tip-in
• Excessive fuel smell or poor fuel economy

Replace the idle jet whenever:
• Performing a carburettor rebuild or tuning service
• You detect uneven idle or mixture issues
• The old jet shows visible damage, corrosion, or deposits
• The vehicle has been stored for long periods or exposed to ethanol-blended fuels

Installing a new idle jet restores accurate fuel metering, ensuring your classic Porsche runs smoothly and maintains its original performance characteristics.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

61610090202

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