High-finish valve-cutter marks Dunedin's
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entry into a new field By A. J. P. Wilding
TN April this year, following the appoint'. ment of a receiver at Dunedin Engineering. Ltd., Dunedin Dieseltune Ltd. was formed with fresh finance to take over the assets of the business. Among the changes which have followed, one of the more important is the formation of a German subsidiary—Dunedin Dieseltechnik—to replace a btanch office in the country. And there have also been changes in the equipment made.
Most of the popular Dunedin range such as the Smokemeter, Injectester and Diestester continue unchanged. But the Timertak design has been altered and two new items of equipment are to be introduced at the Motor Show next week—a fuel consumption meter and valve seat cutter.
The fuer consumption meter is designed for use on petrol-engined vehicles—a diesel version is planned for next year. It is essentially a flow meter with a dial indicator which shows the consumption rate while the vehicle is being driven. Petrol consumption at a steady 30 mph, 40 mph and 50 mph can be obtained. The instrument, which is piped into the line between lift pump and carburetter will be useful for checking differences in performance after modifications or repairs. A version which will indicate the consumption rate per hour also can be obtained.
Change in policy Introduction of the valve-seat cutter marks a radical change in policy by Dunedin, which has hitherto restricted itself to engine test and checking equipment. The tool is the Mira, produced by Baumgartner AG, Switzerland, and Dunedin has taken up the concession for sales in the UK, Eire, Germany and Austria.
To use the Mira machine, the valve head is mounted in a universal jig and clamped in place. The cutting unit is located in the valve guide bore and its bracket then clamped magnetically on to the upper face of the clamping member of the jig. Refacing the valve seat is accomplished manually; as the bit is turned, the cutter is fed on to the valve seat—and it is claimed that the finish is to such a standard that grinding-in of valves is not necessary.
Two carbide-tipped tool bits are supplied and these cover a diameter range up to 55 mm (2.16in.). It is claimed that eight seats can be re-cut in less than 5 minutes.
With regard to the existing Dunedin equipment, the petrol-pump tester has been dropped and the range of Dieseltimers and Electrotaks has been rationalized. The accuracy of the Electrotak has been improved to better than 2 per cent and the transducer used with this machine is now easier to fit into the injector pipeline.
The Dieseitimer enables the timing of a diesel-engine fuel pump to be checked at various speeds in the engine's range. It is particularly useful for checking automatic advance and retard mechanisms. The Electra tak simplifies the checking of engine speed, the transducer in the high-pressure fuel line converting pressure pulses into electrical impulses; the speed is indicated on a directreading scale with ranges of 0-3,000 rpm and 0-6,000 rpm.
The Timertak combines the Dieseltimer and the Frectrotak, and visitors to the Motor Show will see the redesigned version exhibited at Frankfurt last month, The instrument is now more compact and is mounted in a robust case.
To deal briefly with the other main items of Dunedin equipment which have not been changed following the company reorganization:— The Injectester is a simple instrument which is connected into each high-pressure Line from the fuel pump to the injector of a diesel engine. Faults in both the fuel pump and the injectors can be accurately diagnosed under running conditions. Injector operating pressure and needle condition can be checked—and so can the condition of the fuel-pump delivery valves. The Diestester is for measuring compression pressures. It fits into the injector aperture, allowing valve and piston-ring condition to be assessed.
The Dunedin-Bosch Smokemeter gives a permanent record of the degree of exhaust smoke from a diesel engine. There are two parts, a sampling unit and an evaluator. A fixed volume of exhaust gas is drawn through white filter paper by the sampling pump and the density of carbon is indicated when this is put in the evaluator.
Completing the Dunedin range are the Injectascope—which provides facilities for full tests of injectors—a service kit for the Cummins P.T. fuel system and the LP Tester which can be used for checking transfer pressures of DPA pumps, pressure output and suction of fuel-lift pumps and the vacuum on pneumatic governors.