up to this time featured 'corrugated wall' construction with two freeze plugs on the side of each bank and engine mount hole pitch distances of 6 inch. All three block variants from this point on featured the straight wall method of construction, three freeze plugs and an engine mount hole pitch distance of seven inches. The corrugated wall method of block construction had caused cleaning difficulties in the foundry from day one and a change was phased in. 221 The first engine of this family, called the Fairlane V8, introduced for the 1962 model year as an option on the Fairlane and Meteor, had a displacement of , from a 3.5 in (89 mm) bore and 2.87 in (72.9 mm) stroke, with wedge combustion chambers for excellent breathing. An advanced, compact, thinwall-casting design, it was 24 in wide, 29 in long, and 27.5 in tall (610 mm × 737 mm × 699 mm). It weighed only 470 lb (210 kg) dry despite its cast iron construction, making it the lightest and the most compact V8 engine of its type of the era. In stock form, it used a two-barrel carburetor and a compression ratio of 8.7:1, allowing the use of regular (rather than leaded) gasoline. Valve diameters were 1.59 in (40.4 mm) (intake) and 1.388 in (35.3 mm) (exhaust). Rated power and torque (SAE gross) were at 4,400 rpm and at 2,200 rpm. The 221 was phased out end of May 1963 due to a lack of demand after about 371,000 had been produced. 260 The second version of the Fairlane V8 was given the name Challenger, and was introduced during the middle of the 1962 model year (March 1962). It had a larger bore of 3.80 in (96.5 mm), increasing displacement to . Compression ratio was raised fractionally to 8.8:1. The engine was slightly heavier than the 221, at 482 lb (219 kg). Rated power (still SAE gross) rose to at 4400 rpm, with a peak torque of at 2200 rpm. For the 1962 and 1963 car model years, the valve head diameters remained the same as the 221, but for the 1964 car model year, they were enlarged to 1.67 in (42.4 mm) (intake) and 1.45 in (36.8 mm) (exhaust) – this was an economy measure so that both 260 and 289 engines could use the same valves. Rated power was not changed. In 1963, the 260 became