Distributor Calibration

The large bodied Marelli distributors used on Ferraris, Maseratis, Lamborghinis, Alfa Romeos, Fiat Dinos , Fiat 8Vs and others are possibly the finest distributor design ever used in the automotive industry. Their history goes back to their use on the early carbureted Ferraris from the 1950's and they were used well into the 1980's by Ferrari on their fuel injected cars.

Initially designed as a high grade points and condenser type of distributor, over 28,000 of these distributors were manufactured and they were readily adapted for use with electronic ignitions both by the factory and aftermarket suppliers 35 years after their initial design.

Their exceptional reliability both on the road and the track is in some ways their weak point: They functioned so well with little if any maintenance that it is not unusual to find units that have gone over 60,000 miles with nothing other than a change of points, and no other lubrication or maintenance of any kind.

These units were originally designed with a service interval of 10,000 miles. This service consisted of a complete strip down, cleaning and lubrication of all the internal parts, phasing of the points and a measurement of the advance curve. This service interval was very rarely followed principally due to a lack of experience on the part of the new dealers. The majority of them lacked a proper distributor tester, and most importantly, had no idea of how well these cars could perform with properly phased points, correct rotor phasing and perfectly synchronized advance curves.

An experienced technician with the proper equipment could usually perform this service in approximately four hours per car with significant performance gains that far outstripped the costs of this service.

The price we pay in modern times for these missed service interavals is that the majority of these distributors in current use are in very poor tune, and in many cases have internally self destructed from a simple lack of lubrication.

MarelliService is fully equipped with the proper test equiment to restore any of these distributors to their original level of performance using a combination of the best vintage and modern electronic test equipment.

A factory specified distributor calibration service consists of six elements: (1) Disassembly, cleaning and inspection (2) Lubrication and refitting (3 ) Points installation and phasing (4) Testing of rotor phasing (5) Measurement of the advance curve (6) Matching of the advance curves of both units.

Rotor phasing is an entirlely separate process from the normal points phasing, and has long been ignored on these units. Because these distributors are of a a non-self advancing rotor design , it is critical to measure the relationship of the rotor tip to the contact in the distributor cap throughout the RPM range. This can only be done with special fixturing and a stroboscopic tester.

It is possible to easily lose as much as 20% of the available performance from a Ferrari twelve cylinder due to a lack of proper distributor maintenance and calibration, and this, in very real terms can result in the loss of over 40 horsepower in a typical Ferrari 2-cam motor.

Marelli Service specializes in the basic service these units require, and offers full cosmetic and restoration services as well. This type of service is as much art as it is technical science, and ensures that your car will start reliably, perform consistently, remain in service, and bring you all the pleasures of Italian Exotic Car ownership that you have worked so hard to achieve