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The purpose of the distributor modulator system was to help reduce carbon monoxide and hydrocarbons.

Distributor modulator system was standard equipment on some 1970 Ford Mercury Lincoln vehicles. We see it only on the 1970 Mercury Cougar and Ford Mustangs with the M code 351-4V Cleveland engine and FMX automatic transmission.

The purpose of the distributor modulator system was to help reduce carbon monoxide and hydrocarbons. Sometimes it is referred to as the Dist-o-vac system. The basic premise of the system was to use carburetor venturi vacuum to reduce engine emissions. This was performed by controlling distributor spark advance. A retarded spark provides hotter combustion chamber and exhaust manifold temperatures that cause more complete burning of the fuel.

The three main components are the Electronic Control Module, Speed Sensor, and Thermal Switch.

  • Electronic Control Module is the black box which houses the PC board and solenoid valve. Ford part D0AF-9E718-S, in the manual it is described as having a black box and a blue cover, we also see them with black covers on the black box.

    *Side note – There is also a white colored box along with black, blue, and white covers. This combination of boxes and lids make for 6 differently identified units for a range of other applications.

  • Speed Sensor this actually is often confused with a cruise control part. It mounts inline on a two piece speedometer cable, it also has a two wire plug coming out of it. Ford part number D0AF-9E731-A.

  • Thermal Switch this measures temperatures and only engages the modulator system on, at temperatures above 58°F. Ford part number D0AF—12A164-B.

 

For a 1970 Mercury Cougar or Ford Mustang the black module box will 'cut in' at speeds of approximately 23 mph and 'cut out' when speeds fall below 18 mph, provided that ambient temperatures are about 58°F.

There is other related wiring and vacuum lines involved that we will try and include. There were also two similar systems on the 1972 Mercury Cougars. TRS Transmission Regulated Spark and ESC Electronic Spark Control are the names of the two systems.  As time and information presents itself, we will include that system in the future.

 


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Price: $43.85

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Availability: Used / Wrecking Yard Item
Item #: 25005 -

Used distributor modulator thermal switch for the Mercury Cougar or Ford Mustang equipped with the M code 351C-4V engine and FMX automatic transmission. Originally this switch was mounted in the drivers side door jamb and had a bimetal strip that was calibrated for ambient temperatures between 50 and 58°F. We dont have a way to test these, so they are sold as is. Ford part # D0AF-12A164-B.

Price: $29.85

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Availability: Used / Wrecking Yard Item
Item #: 31268 -

Used distributor modulator thermal switch for the Mercury Cougar or Ford Mustang. Originally this switch was mounted in the drivers side door jamb and had a bimetal strip that was calibrated for ambient temperatures between 50 and 58°F. We dont have a way to test these, so they are sold as is. Ford part # D2AF-12A164-C

Price: $72.85

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Availability: Used / Wrecking Yard Item
Item #: 25009 -

D0AF-9E718-C Distributor modulator control module for 1970 Mercury Cougar and Ford Mustang with the M code 351C-4V engines and FMX or automatic transmission. The 'black box', supposed to have a blue cover, The Autolite Shop Tips guide describes this box as having a blue cover and a stamped part number of D0AF-9E718-S. The Ford MPC shows a master part number of D0AZ-9E718-C, and a box marked D0AF-9E718-C.

Price: $49.85

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Availability: Normal Stock Item
Item #: 31269 -

Used control box for the spark control system on the 1972 Mercury Cougar or Ford Mustang. Ford part number D3AF9E447

Price: $49.85

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Availability: Used / Wrecking Yard Item
Item #: 31266 -

Used control box for the spark control system on the 1973 Mercury Cougar or Ford Mustang. Ford part number D3AF9E447

Price: $121.85

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Availability: Used / Wrecking Yard Item
Item #: 25249 -

D0ZZ-9A820-B Distributor modulator lower speedometer cable for 1970 Mercury Cougar and Ford Mustang with the M code 351C-4V engine and FMX or automatic transmission. Used on cars manufactured before 12-15-1969. Long cable that connects the speed sensor and the FMX transmission of the modulation system. Shown to be 45.25 inches long. Please see D0ZZ-9A820-H for the upper cable section. Please see D0ZZ-9A820-G for cars manufactured after 12-15-1969.

Price: $121.85

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Availability: Used / Wrecking Yard Item
Item #: 25250 -

D0ZZ-9A820-G Distributor modulator lower speedometer cable for 1970 Mercury Cougar and Ford Mustang with the M code 351C-4V engine and FMX or automatic transmission. Used on cars manufactured after 12-15-1969. Long cable that connects the speed sensor and the FMX transmission of the modulation system. Shown to be 49.24 inches long. Please see D0ZZ-9A820-H for the upper cable section. Please see D0ZZ-9A820-B for cars manufactured before 12-15-1969.

Price: $72.85

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Availability: Used / Wrecking Yard Item
Item #: 25010 -

D0AF-9E731-A Distributor modulator speedometer cable speed sensor for 1970 Mercury Cougar and Ford Mustang with the M code 351C-4V engine and FMX or automatic transmission. Mounts inline on a two piece speedometer cable. Ford master part number D0AZ-9E731-A.

Price: $72.85

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Availability: Used / Wrecking Yard Item
Item #: 31262 -

Used distributor modulator speedometer cable speed sensor for 1972 - 1973 Mercury Cougar and Ford Mustang. Mounts inline on a two piece speedometer cable. Ford master part number D2AF-9E731-A.

Price: $61.85

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Availability: Used / Wrecking Yard Item
Item #: 25072 -

D0OZ-12A163-B Paired steel tubes that run along the driver side valve cover. Used on the 1970 Mercury Cougar, Mercury Cyclone, Ford Torino, and Ford Mustang with the M code 351C-4V engine and FMX or automatic transmission.

Price: $61.85

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Availability: Used / Wrecking Yard Item
Item #: 25251 -

D0ZZ-9A820-H Distributor modulator upper speedometer cable for 1970 Mercury Cougar and Ford Mustang with the M code 351C-4V engine and FMX or automatic transmission. Cable that connects the back of the speedometer and the speed sensor of the modulation system. Shown to be 10.54 inches long. Please see D0ZZ-9A820-B or -G for the lower cable section.

Price: $61.85

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Availability: Used / Wrecking Yard Item
Item #: 31263 -

Used distributor modulator upper speedometer cable for 1971 - 1973 Mercury Cougar and Ford Mustang with the FMX or automatic transmission. Cable that connects the back of the speedometer and the speed sensor of the modulation system. Shown to be 10.54 inches long. 

Price: $39.85

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Availability: Normal Stock Item
Item #: 31270 -

Used wiring harness for the spark control box for the 1972 Mercury Cougar or Ford Mustang . This is only the harness, you can find the control box here.

Price: $39.85

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Availability: Normal Stock Item
Item #: 31265 -

Used wiring harness for the spark control box for the 1973 Mercury Cougar or Ford Mustang . This is only the harness, you can find the control box here.

Price: $42.85

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Availability: Used / Wrecking Yard Item
Item #: 25245 -

D0ZZ-9A474-A Vacuum fitting for the rear of the intake manifold on a 1970 Mercury Cougar or Ford Mustang with the M code 351 Cleveland 4 barrel engine. Has two vacuum nipples or ports. 1970 Mercury Cougar Ford Mustang Modulation System - Bleed Assembly - Used D0AZ-12A168-C Very small inline vacuum hose bleed valve assembly installed very close to the distributor modulator control box.

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