model year, GM shifted Buick, Oldsmobile, and Pontiac versions of the B-body sedans to the front-wheel drive H-platform with a further round of downsizing, with station wagons becoming distinct model lines on the B platform (only the Chevrolet Caprice remained as both a sedan and station wagon). Chassis The second-generation Oldsmobile Custom Cruiser (as with all full-size GM station wagons) is based on the GM B-platform. As part of the GM downsizing, station wagons were consolidated upon a common 115.9 inch wheelbase shared with wagons of all three mid-price divisions and Chevrolet (and all B-platform sedans). In the redesign, the Custom Cruiser shed 14 inches in length, 11 inches of wheelbase, and up to 900 pounds of curb weight (though becoming taller). Though sharing its wheelbase with the intermediate Vista Cruiser (and nearly 200 pounds lighter) prior to its 1978 replacement, the Custom Cruiser remained in the full-size segment, as its body was several inches wider and taller. As Buick, Oldsmobile, Pontiac (and most Cadillac) full-size sedans were downsized further to the front-wheel drive C-body and H-body platforms in the mid-1980s, after 1986, the rear-wheel drive B-platform remained solely for the Chevrolet Caprice and Buick, Oldsmobile, and Pontiac station wagons (with the Pontiac Safari ending production after 1989). Powertrain At its 1977 launch, the second-generation Custom Cruiser was offered with two engines, a 170 hp 350 cubic-inch Oldsmobile V8, with a 185 hp 403 cubic-inch Oldsmobile V8 as an option. For 1979, both engines were detuned: the 350 was detuned to 160 hp and the 403 offered 175 hp. After 1980, both the 350 and the 403 were replaced by the 307. For 1980, Oldsmobile introduced its third (and last) V8 engine for the B-platform, the 307. Initially producing 150 hp, the 307 was detuned to 140 hp for 1981. For 1985, new "swirl port" cylinder heads were given to the 307. While engine horsepower was not increased, the design increased torque and driveability; at the expense of high RPM power and performance, the heads featured relatively small intake ports. Along with the new cylinder heads, roller lifters replaced flat lifters. For 1980 in California-market examples, Oldsmobile introduced a new E4ME electronic carburetor, using CCC (Computer Command Control); in 1981, the 4-barrel carburetor was adopted in all 50 states, replacing the previous mechanical M4ME version. In Canada, E4ME was not adopted until 1986. 1977-1990 Custom Cruisers were fitted with two