General Information on the '71 429 Mustang and Cougar Emission Systems (by J. Gentile)

429 CJ cars had what Ford called the IMCO system, for IMproved COmbustion. It consisted of modifications to ignition timing and fuel mixture. Things that accomplished this included the Q-jet carburetor, the dual diaphragm distributor, and a throttle solenoid which helped to prevent over run on shut off. Another device (often missing today) is a thermostatic switch atop the vacuum distributor fitting (on the thermostat housing) which served to advance the timing (thus boosting engine speed) when the engine heated up during prolonged idle. CJ cars did not use the Thermactor (air injection) system.

429 SCJ cars are more interesting. All of the original ones I have seen were equipped with the Thermactor system, similar to the that on 428 CJ and Boss 429. The biggest difference is the air injection is routed to the back of the cylinder heads on the 429, as opposed to the individual exhaust port areas on the FE engines. I have been told the less precise fuel mixture control of the Holley mandated the air injection to keep emissions under control (It is also said Ford's desire to get away from Thermactor is why they went with the Q-Jet on the CJ. They had to go with the Q-Jet because their own big smog carburetor, the 4300D, wasn't ready when the 429 CJ went into production. The 4300D finally appeared on the 429, but not until 1972 as the 429 Police Interceptor. Both it and the 4300D Boss 351 of 1971 and 351 CJ and HO of 1972 avoided air pumps.)

(Note: Click thumbnails to enlarge pictures.)

429 SCJ Thermactor System

System Overview

Complete Thermactor System

The complete Mustang/Cougar/Torino SCJ smog system was taken from the 70 -71 460 Lincoln line, except for the pump pulley, which is a unique 70 T-Bird part. The pulley may have been left over parts stock, since "smog" wasn't available for the 70-71 429 T-Bird. This would make the SCJ smog pulley quite rare today. An assembled 429 SCJ Mustang system is shown above and all of the individual components are below. Note the very rare D0SE pulley in the photo below right.

View of System Installed

The photos above are of the Smog system on Fred Coyner's low mileage all original 429 SCJ Mustang. The smog pump pulley was stamped D0SE-9C480-A, and had a 5 1/2" diameter with a 15/32" sheave.

Details on Smog System Components

SMOG (Thermactor) Pump

Here is the 68-71 Thermactor pump (C8AZ-9A486-C) used on the 429 SCJ Mustang. This pump featured a round pressure relief valve in it's side. The color of the valve was blue with a gold cad frame. The pump itself was bare aluminum, with an aluminum 90 degree hose nipple. The pump also had a semi-black cast iron rear housing with silver hardware. The pump used a white centrifugal filter fan in the front, and the pump's shaft end was painted yellow. If you're looking for a Smog pump, note that pumps from the mid 70's will work, but they didn't contain the pressure relief valve.

Attachment/Mounting Parts

The photo above left shows the smog belt adjustment bracket (long one) which was marked D0VE-9B452- A. Just below this is the small triangular bracket (marked D0VE 9C486 A) that held the by-pass/diverter valve to the belt adjustment bracket. This triangular valve bracket, along with the 2" round clamp was only used on cars built before 3/1/71. The SCJ water pump pulley, which was the same as the CJ w/ PS w/o A/C, was marked D0OE-8509-M. To the left of the pulley is the alternator bracket. The pumps mounting bolt was 6" long, and the pumps spacer was 1 13/16" in length (photo at right).

Smog Pump Mounting/Alternator Bracket

In the photo above left, the bracket on the left is the SCJ Alternator /Smog Pump Bracket (D0VE-9B450-A) while the one on the right is the CJ Alternator Bracket (D0SE-10156-A). These brackets can be found on other 429-460 engines. At right is another photo showing the SCJ Alternator/Smog bracket.

Smog Belt Adjustment Bracket

The pictures above show two angles of the D0VE-9B452-A smog pump belt adjusting bracket. The red arrow shows the installation location of the D1VE-9C486-AA by-pass valve mounting bracket.

Below are installed views of the D0VE-9B452-A smog pump belt adjusting bracket.

Bypass/Diverter Valve

Here you can see the air by-pass/diverter valve with it's cover in place. The cover was stamped C8TE-9B289-B, and also was stamped with the valve's build date. Normally, the pumps output air flowed to the cylinder heads exhaust ports whenever the engine was running. What this did was inject fresh oxygen into the hot exhaust gas, and this caused any remaining unburned fuel to be re-ignited in the exhaust port and be reburned to lower the exhaust emission level. Now, during times of engine deceleration, the pump's air flow was diverted for 3 seconds from the cylinder heads, and sent to the 2 oval exit slots in the by-pass valve's cover. The cover also acted as a muffler for this by-passed air. The by-pass of the pump's air from the exhaust ports was done to prevent exhaust backfiring during engine deceleration when the engine's air/fuel mixture would go slightly too rich. You will sometimes see the by-pass valve called an "anti-backfire valve". The Pump to Diverter Valve Hose and correct attaching clamps are shown at loer right. This short "S" hose was 8 3/4" long, and was stamped C8AE-9F287-A.

Bypass/Diverter Valve Mounting Brackets
There were two different mounting schemes for these Bypass/Diverter Valve. These are described below.

Bypass Valve Bracket used from 8/70 thru 2/71

The triangular bracket shown above left is the by-pass valve mounting bracket that was used on cars built from 8/70 thru 2/71. It's part number is D0VE-9C486-A.

The D0VE-9C486-A by-pass valve mounting bracket mounted to the D0VE-9B452-A smog pump belt adjusting bracket (above center and right).

As shown below, the by-pass valve is placed in the curved saddle formed by the D0VE-9C486-A mounting bracket and a clamp goes around the by-pass valve housing and tightens against the curved underside of the mounting bracket. An installed view is shown below right.

Bypass Valve Bracket Change on 3/1/71

The diagram above shows the by-pass valve mounting bracket that was used on cars built from 3/1/71 on. The bracket switched from the triangular D0VE-9C486-A to the D1VE-9C486-AA shown in the photos above on 3/1/71.

The photos below show the D1VE-9C486-AA by-pass valve bracket mounted to the end of the D0VE-9B452-A the smog belt adjustment bracket..

The photos below show how the curved surface of the D1VE-9C486-AA bracket clamps to the hose (Smog Pump to by-pass valve).

A final installation view of By-Pass Valve on the 3/1/71 level bracket is shown below. Note that the By-Pass Valve is clocked so the rear of the canister is pointing at 1:00 (instead of 12:00 on the pre 3/1/71 design). This clocking of the valve was necessary to gain clearance between the support bracket and the nipple on the bottom of the canister. This angle change is also shown in the MPC diagram at lower right.

Evaporative Emissions Recovery - Charcoal Canister

The charcoal canister was found on bothe the 429 CJ and SCJ applications.

Charcoal Canister

This is the charcoal canister. It was mounted in the engine compartment (rear of passenger side as shown above) to the inner fender apron with a bracket. The inlet side (small fitting) hooked up to a tube from the fuel tank. The outlet side (larger tube) ran to a fitting on the air cleaner (with a filter element). When the engine was running, it served as a system to aspirate and burn excess gasoline fumes to prevent the fumes from escaping to the atmosphere. Additional photos of the canister and it's attachment bracket are shown below.