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The Different Triumph PI Setups

The Lucas PI system was successfully used in Formula 1 racing in the 1960s. Triumph was the first UK manufacturer to fit fuel injection to their production cars in the UK. The Lucas Mk2 PI system was fitted to TR5s, TR6s and 2.5 PI Saloons and Estates.

Although the basic system remained the same, the throttle bodies, throttle countershafts, linkage rods and springs inside the metering unit varied throughout production. Over the years, the Lucas PI systems from saloons have been fitted to TRs, and 125HP systems fitted to later TRs have been replaced with earlier 150HP systems. As such it is quite possible that you may have parts fitted to your car that are from a different model.

The countershafts, throttle rods and swivel posts vary on the different models and were also modified on the later versions of the same model. Whilst some components such as the length and designs of throttle rod are obviously different, there are many variations of the swivel posts and countershafts which are not so obvious.

Classic Lucas Petrol Injection Advert

Click on the links below to see the pictures, diagrams and descriptions of the linkages fitted to different models, which should help you to identify what system is fitted to your car:

Note: The Mk 1 2.5PI throttle bodies, rods and countershaft can be fitted straight onto a TR without issue. The same goes for the later CR Mk 2 throttle bodies with the twin air balance pipes. The long levers on the countershaft of the early MK2 setup make it unsuitable as the levers foul the exhaust. Mk1 and early Mk2 2.5PI throttle bodies can be adapted to use the TR countershaft and throttle rods by replacing or modifying the butterfly spindle in the rear throttle body. Care should be taken when mixing throttle assemblies from 2.5PIs and TRs as some of the parts (especially Mk1 2.5 PI and CP countershafts) look very similar but are not interchangeable. If you need help identifying parts, or getting a mix of parts to work, contact us and we will help you out. 

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