A Nitrogen Oxide (NOx) Control System was incorporated on all 'Cuda340 cars sold new in California. Improved combustion efficiency provided a more complete burning of fuel-air mixtures to help reduce photochemical smog. By using a lean mixture and retarded ignition timing, most of the fuel was burned in the lower part of the power stroke during acceleration. The control unit assembly consisted of a vacuum switch, a thermal switch, and a control module. Although all components were incorporated on vehicles sold new in California, some components were included in vehicles for nationwide sale. These modifications included:
• Higher overlap camshafts that allowed more exhaust gas dilution which caused a lower peak burning temperature during combustion.
• Restricted usage of the distributor vacuum advance unit. No spark advance was available on acceleration up to 30 mph. Use of the vacuum advance is restored at ambient temperatures below approximately 68 degrees F.
• Modified centrifugal spark advance curves.
• Manual transmissions that have a switch in the transmission case or shift housing that deactivates the NOx system when the transmission is in high gear. On the A833 4-speed, it is located in the shift housing below the 3-4 shift lever and is actuated by a cam on the lever. Vehicles not equipped with this system have a solid plug instead. Automatic transmissions use a speed switch in the speedometer drive system.
Option code N98 included this decal affixed to the driver-side rear window. Higher demand for cleaner air and lower emissions began in California. This decal indicates the maximum emissions allowed for new vehicles.
Unibody
A unitized body and frame (or unibody) make a more rigid car. The heavy-duty frame structure was welded into the metal body, which provided a stronger passenger compartment. More than 5,400 welds unite the structural steel members, body braces, and body panels into a single unit. This resulted in a stronger, tighter, and more durable structure with less shake and rattle than cars with bodies bolted to separate frames. Plymouth used narrow doorsills because the unibody didn’t have a perimeter-type frame to take up. This provided more foot room in front and in back.
Chrysler-Plymouth used a unibody design that featured many safety factors to protect the occupants. Boxed sections, cross braces, and thousands of welds all added structural integrity. (Dodge, Plymouth and the AMC design are registered trademarks of FCA US LLC)
Body Reinforcements
Extra body safety was achieved in the 'Cuda by welding strong steel side-impact beams into each door. Reinforcements were also added to the door lock pillars and the door strikers. An extra roof-beam structure on the hardtops acted as a roll bar. It was welded to the rear wheel housings and extended up the roof pillars and across the roof. In addition, a box section was added on the inside of the windshield header and pillars. These heavy-gauge steel side sills have four-sided construction for extra strength and are galvanized on the inside to resist corrosion and rust. After construction, they received a seven-step dip and spray anti-rust treatment. The car was coated with epoxy primer before being sent off to the paint shop for acrylic enamel paint.
Additional boxed steel sections were incorporated for rollover protection and side-impact accidents. The large door openings benefit from a large welded-in section of thick steel for added driver safety. A fully dressed door weighs a hefty 105 pounds. (Dodge, Plymouth and the AMC design are registered trademarks of FCA US LLC)
A newly manufactured steel unibody was treated to a seven-step protective process prior to two coats of epoxy primer. Finally, the acrylic enamel exterior color was applied and oven-baked. (Dodge, Plymouth and the AMC design are registered trademarks of FCA US LLC)
Insulated Unibody for Silence
Insulating and sound deadening were a big part of Plymouth’s scientific approach to achieving a car body that was tight and quiet. Materials that insulate, isolate, dampen, and absorb were placed to eliminate body sounds in the following areas:
• Steel roof bows bonded with adhesive sound-deadening material
• Floor covered with jute padding bonded to the underside of the carpet that also included a layer of polyethylene used as a moisture barrier between the jute and carpet
• Door, quarter panels, and wheel housings sprayed with a heavy undercoating of mastic sound-deadener
• Rear roof pillars with dry felt pads in the pillars
• Single-ply insulation board between the passenger compartment and the trunk
• Asphalt-impregnated pad forms sound and insulation barrier between gas tank and underbody
• Hood and trunk lid inner and outer steel panels bonded together with adhesive sound-deadener, which made them sturdier and prevented drumming
• Package shelf insulation, a 1/10-inch-thick dry felt pad
• Optional fiberglass hood silence pad aspart of the undercoating package
• Half-inch-thick fiber insulation blanket cemented to the underside of the roof
• Dash and cowl panels with a multi-layer blanket comprised of fiberglass, asphalt-impregnated felt pad, and hardboard cover that reduced noise and engine heat.
Government regulation stated that each purchaser of a new car must receive certain performance information about that car. The 'Cuda contains this Consumer Information document in the same plastic container with the owner’s manual.
Early-build cars were still using some of the 1970 model assembly line items. These parts needed to be used for several reasons, but the primary reason was because the inventory had to be depleted before new stock could be ordered. Late-build cars also used the 1972 model year–items. These items are seldom noticed and often restored incorrectly. I have seen many of these unusual items on factory-built cars.
The inner fender on the passenger side was installed without the recess for the vapor recovery line. Until mid-September 1970, the assembly worker drilled the mounting bracket holes wherever it lined up. The SHAKER hood came without underframe crumple zones (until mid-November 1970). And, until late September 1970, the center console had the rear seat belt holder instead of the rear ashtray.
This 'Cuda340 convertible shows graceful lines with the top down. Glacial Blue Metallic paint code GB2 exterior color was applied to 2.6 percent of the U.S.–specification production cars. These handsome 14-inch Road Wheels originally came with F70 × 14 tires with Raised White Letters (RWL). (Eric Andersen Photo)