The Impala broke the all-time industry yearly sales record in 1965 with more than one million units going out the showroom doors. The ‘65 sales record remains unbeaten to this day. The fourth generation is revised bottom to top featuring a full coil spring suspension to support the new full width perimeter chassis. The green house glass windshield has a sharper angle, no-draft windows reshaped, and the side windows are now frame-less in the hard top versions. Mid-year ’65 the newly introduced Caprice is in show rooms as an option package for the four door hard top. The Caprice “Halo” model has tufted upholstery, simulated wood grain vinyl accented interior, with unique hand pulls on the door. The Caprice exterior sports SS “spinner” wheel covers with the bow tie logo in place of the SS emblem and also borrows the SS black-out strip below the tail lights minus the SS emblem.
The 1966 model year sees the Impala takes a back seat with the Chevrolet Caprice as the uptown full size luxury model. The inline six cylinder engine is still available but most opted for one of the V8 choices. There is finally a new three speed automatic back in ’66 after a four year hiatus, reinvented as a Turbo Hydra-Matic, and it is readily acquired by purchasing the new big block 396 cu in Mark IV V8 engine. The 396 replaces the deleted 409 early in the ’65 model year but a few 409 engines did make it out of the showroom. The two speed Power glide automatic is still available as well as a four speed and the three speed transmissions are there to be chosen but this year both synchro-meshed gears. The Impala line-up is flashing a lot of chrome on the exterior this year. With interiors looking good featuring pleated-tufted seating and door panels which is set off with an abundance of chrome trim strips. The Chevy Impala convertible had 38,000 happy new owners in ’66; it was second bestselling unit in North America and chosen by double the number of customers that purchased a Mustang rag top.
The sheet metal is revised on the Impala in 1967; the front and rear fenders now have a bulge following the Corvettes example. Both this year and next the smooth lines are tending more towards the coke bottle shaped body. In order to comply with federal safety regulations this year the complete GM lineup comes equipped with impact absorbing steering column, marker lights on either side, and have a shoulder harness.
The Impala models have a revised front fascia for 1968 and the triple tail light configuration is the shape of a horse-shoe and nestled in the bumper this year. The Custom coupe is new for ‘68 with the same conventional roof line as the Caprice Coupe.
The 1969 Impala has shed the sinewy coke bottle look; radically revised the side panels are flat with up swept rear quarter windows give the car a more refined look. The automobile is still on the same wheelbase but the size is emphasized the designers are trying to make the car appear larger with the new wrap-around bumpers front and rear and it does look wider. The old style no draft worked well but added wind noise so for ’69 the vent windows are scrapped and all models of Impala have a basic flow through ventilation system with bringing fresh air into the cabin through dash mounted adjustable ports. This supplies lots of fresh air and save the company some cash as well with the ports also serving as the delivery system for the optional air conditioning units. All models have the ignition switch on the steering column which is now a locking design as is the shift lever. A notch back roof line is now featured on the hard top sport coupe. The 1970 Impala is the end of the 4th generation is altered minimally with the front bumper now under the grill and the rear tail lights are now vertically configured and mounted in the bumper. The Canadian customers have an added Sport Coupe model available in the body of the Bel-Air for the budget minded sport fans.
The Dodge Custom 880 was in production from 1962 through to 1965 and the '64 has received a complete body change over previous years. This model did well for the Dodge Division that year, with 31,800 units produced, but fewer convertible versions. A seldom seen feature, unique to Mopar, is the dash mounted push button shift mechanism.
After a five year hiatus from passenger cars the hemispherical engine is revived-in the second generation (G2) by Chrysler in 1964 and is sold as “The Hemi” which is now a trademark of the corporation. This newly released 426 cu in engine is large and heavy as well. It comes by the moniker of the “elephant’ honestly. The engine has a tall deck-at 10.72 inches (272.3 mm) with bore spacing of 4.80 inches (121.9 mm) and formidable width as well, a large engine compartment is needed to accommodate the size. This power plant is also pricey by comparison for the day so there were only 11,000 of them manufactured. The Plymouth Belvedere raced with this engine under the hood on NASCAR circuits in 1964. I n 1965 the engine was not allowed on NASCAR circuits because there were too few units available in showrooms. The engine became more widely available to the public for the 1966 model year when the street version is introduced which allowed the power plant to again be seen on NASCAR tracks.
The complexity of the valve train makes this hemispherical engine expensive to produce but it does improve the power plants high RPM respiration in any production automobile. NASCAR mandates only two valves are allowed in each cylinder but by increasing the angle of the valves in relation to the piston the valve size can be increased significantly. The configuration also allows room for additional valves to be added.
The 426 hemi is oversquare; the bore is 4.25 inches with a 3.75 inch (95.3 mm) stroke which immediatly made it a desirable power plant for the NHRA drag racing tracks. It is also an easy engine easy to bore to sizes unattainable with other blocks of this time period, Stroked and blueprinted this is the engine to best in all segments of funny car and top fuel racing. The track version often has a roots supercharger mounted on the intake, duel exhaust pipes, and can be powered by nitromethane.
The street hemi 426 engine was widely available for most high performance and high end Dodge or Plymouth models from 1965 until 1971. The engine was also available as a power option for the Dart in the 1968 model year if you could afford it although this car was not street legal. There was a prototype also made called the Monteverdi Hai 450 SS with the 426 hemi under the hood. The car was built to be in direct competition with Lamborgihini, Ferrari, and Maserati. The original production called for 49 units to be built when unveiled at the Geneva Motor Show in 1970 but production was halted after only two units were produced. The street hemi is much different than the conventional wedge headed big block version including the main bearing caps and the bolt pattern of the heads. The racing 426 hemi and the street edition sported different compression ratio, camshaft, both intake and exhaust manifolds as well as many lesser parts are also not the same. Some of the racing units in the ‘60’s integrated magnesium cross-ram air intakes and magnesium oil pans for the dry sump oiling system in an attempt to cut down the overall weight. Most aftermarket parts today-including pistons, con rods, heads and blocks are often made of aluminum.
Out of the showroom the 426 would produce 425 bhp (316.9 kw) gross and develop 472 lb-ft (640 Nm) of torque although real world testing rate the engine as producing 433.5 hp. The sales brochures in 1971 give the gross 425 hp (317 kw) with the net figures of 350 hp (261 kw) shown as well.