Fulvia Thoughts - 4

And today's subject is...

The Alternator.

The alternator fitted to S2 and S3 cars and also Fanalones is really a rather feeble item. Rated at 28 amps, it is potentially not up to the job. Consider a rainy, cold night. Driving in your S2 coupé (or sedan for that matter), you have the headlamps, heater, heated rear window and wipers all running. With the sidelights, I estimate the total power consumption at 390W. At 13.5V, this represents 25.9A, rather close to the limit even for a perfect alternator (more of that later) and if you run main beams and fog/driving lamps as well, then you had better have a very good battery!

Of course I have given a fairly extreme example, but I believe that equipment should always be up to the job with a margin to spare.

Early S2s and Fanalones are fitted with Bosch alternators and starter motors. Late S2s and S3s have Ducellier equipment. Most people seem to agree that the Ducellier equipment is not as good as the Bosch, and based admittedly only on impressions rather than tests, I am inclined to this view.

Testing your alternator is a fairly simple matter if you have a suitable voltmeter or multimeter. With the engine running connect the meter across the battery. The voltage should read between 13.5 and 14.4V. Next switch on the headlamps. The voltage will drop, but it should not drop below 12 – 12.5V. Then increase the engine speed, watching the meter. As the alternator turns faster, it should deliver more current, causing the voltage to rise. The voltage should return to a minimum of 13.5V. If it does not, then the most likely cause is either a failed diode in the alternator or perhaps regulator trouble. Many Fulvia owners will have noticed the warning lamp glowing gently when the headlamps are switched on; this is an indication that all is not as it should be!

In the past I experienced both of these problems. The cost of rebuilding an alternator is quite substantial and so my first solution was to fit an alternator from a 2000. This fits directly onto the Fulvia mountings; the only change required is a shorter drive belt (from memory 750mm rather than 775mm). Electrically there are no problems if you have Bosch equipment. On Ducellier cars you would need to change the terminals connecting the (Ducellier) regulator to the alternator. The 2000 component can deliver 55A so is unlikely to be stressed and should last well. Please note that the Fanalone has a different arrangement with a double pulley. I have not attempted the conversion to a 2000 alternator on Fanalones, but I think it might not work because of the different block mountings.

However, the fact remains that the 2000 unit is rather bulky, limiting adjustment somewhat on 1300s and quite a lot on 1600s, because of the larger carburettors.

For my own car I finally found a Japanese alternator from an old Mitsubishi Colt. Quite a lot of work was required to fit it but I have never regretted it. It is about the same size as a standard Fulvia alternator, but delivers 55A (in fact I have seen 65A versions) has a built-in regulator and has been reliable.

Finally, for those who are better off, there are several specialist companies who supply excellent lightweight alternators intended for competition cars. These cover a wide range of outputs and the firms concerned offer a range of mounting accessories.