PTD changeover
Page 17
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Cummins 12.2 litre (744 cu in) engines more than one year old can now be fitted retrospectively with the latest PTD type of injector, similar to those subsequently fitted as standard in all NH/NT series Cummins diesels.
Engines affected are primarily those designated
NH195/205/220.
Although they can be substituted directly for the older PT types, a revised fuel pump calibration is involved which means a complete injector change is necessary — it is not possible to mix the two types.
Because of the closer fit of the PTD injector plunger in its barrel — made possible by a reduction in barrel length — plunger movement (and therefore fuel metering) are controlled more precisely.
Commencement of injection and out-off point are 'sharper' which has the effect of marginally advancing injection timing.
For a limited period of six months, starting from December, a set of six service exchange PTD injectors and rocker levers is being offered at a special cost of £108, about 50 per cent less than the normal retail price.