The Triumph Dolomite Club - Discussion Forum

I read in the history file of my Sprint it was booked in for the conversion to allow it to use unleaded fuel.

However, there is a letter from the garage saying Sprints didn't need the conversion done as the valves adapted well to unleaded fuel.

Does this make any sense to anyone?

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Sprints need no conversion, the oem factory valve seats are hard enough. Most cars back then had iron heads which do need cutting to take inserts. A sprint alloy head, an exotic innovation at the time, requires valve seat inserts anyway.

The garage is correct but for the wrong reason. They are referring to the effect known by many names, lead memory being one, whereby there's enough lead leached into the cast iron that the head copes. This is a limited life effect. A car that did 10k a year on 4 star and then only 500 a year to the occasional show on unleaded would be fine for decades but the embedded lead does run out. At least, that is my interpretation of 'adapted well'.

Ahh that's great - thanks for clarifying that's.