Oldsmobile Cutlass W-31

Cutlass W-31 at a glance

A small-block answer to the 4-4-2

The W-31 gave Oldsmobile a performance Cutlass below the 4-4-2. Car and Driver noted that the two cars shared body and chassis, while the 4-4-2 used a Rocket 400 with 50 more cubic inches. The small-block car cost less: SlashGear reports that a W-31 F-85 coupé saved over US$400 against a W-30-equipped 4-4-2. In 1968 the package was sold as the Ram-Rod 350 on the F-85 Club Coupe, the Cutlass coupé and the Cutlass Supreme coupé.

Hemmings describes the hardware. The engine used the regular 350 cylinder-head castings of 1968, marked "5", fitted with the larger 2.00 in and 1.625 in valves from the 455, plus a thicker harmonic balancer. Ram-air scoops under the front bumper fed tubes through the wheel arches to a dual-snorkel air cleaner. The 308-degree camshaft gave a choppy idle and so little manifold vacuum that the first cars could not have power brakes, and the 1968 W-31 came with a three-speed or four-speed manual only.

The Ram-Rod 350 engine

The 350 had a bore and stroke of 103.1 x 86.1 mm (4.06 x 3.39 in) and a cast-iron block with five main bearings. Old Cars Weekly lists 242 kW (325 hp) at 5,400 rpm and 488 Nm (360 lb-ft) at 3,600 rpm with 10.5:1 compression; another period summary quotes peak power at 5,600 rpm. The camshaft had 0.474 in of lift and 82 degrees of overlap, and the Rochester 4MV Quadrajet ran without a power valve.

Oldsmobile used select-fit pistons, bearings and crankshafts, plus connecting rods made only for the W-31. A heavy-duty radiator and a six-blade fan with a clutch handled cooling. Roger Huntington of CARS magazine calculated about 231 kW (310 hp) net at the clutch at 6,000 rpm, close to the gross rating, as quoted by Car and Driver.

Year by year, 1968 to 1970

The 1969 automatic was a specially calibrated Turbo Hydra-Matic 350, and the air cleaner lid still read Ram Rod. For 1970 the W-31 took the W-30's striping and similar die-cast fender emblems. The package cost US$368.62 (1970) on a Cutlass S that started at US$2,970 (1970), or US$591.17 (1970) with the 3.91:1 G88 axle and anti-spin differential.

The 1970 parts list included the FE2 Rally-Sports suspension with heavy-duty springs and 1-inch anti-roll bars, manual front disc brakes, 14 x 7 inch wheels, a full dual exhaust and lighter body insulation. Buyers chose the M14 three-speed with a Hurst shifter, the M20 wide-ratio or M21 close-ratio four-speed, or the M38 Turbo Hydra-Matic 350 with a 2,600-2,900 rpm stall converter. Of 88,578 Cutlass S Holiday coupés built that year, 1,145 had the W-31.

What the magazines measured

Car and Driver started from a Cutlass S V8 Holiday Coupe listed at US$2,838 (1969) and added the W-31 package at US$310.69 (1969). Its car reached 30 mph in 2.2 seconds, ran to 115 mph during the test and was estimated at 212 km/h (132 mph) flat out. Unassisted 9.5-inch drum brakes needed 93 m (305 ft) to stop from 80 mph, and 56.5 % of the weight sat on the front wheels. The magazine summed up the car as "complete soul, all the difference between transportation and a trip."

Why the W-31 ended after 1970

Hemmings writes that the W-31 was never very popular and that Oldsmobile dropped it quietly after 1970. Its 3,007 cars in three years were a small share of Cutlass output. For 1971 GM lowered compression across its range, and the 10.5:1 W-31 did not return. Oldsmobile's other 1970 small-block special was the yellow Cutlass Rallye 350.

Among rival small-block cars of the period were Plymouth's Duster 340 and Chevrolet's Camaro Z28.

Cutlass W-31 today: what to check

With 3,007 cars built in total, every W-31 is scarce, and the 1969 convertible, with 26 built, is the scarcest version. Tribute cars are common because the 1970 bonnet, stripes and emblems were shared with the W-30.

• 1968: Ram-Rod 350 fender decals, manual gearbox, manual brakes.
• 1969: small W-31 decals near the marker lights and an air cleaner lid with the Ram Rod name.
• 1970: the "W-350" intake manifold, "6" head castings and the Force-Air bonnet with chrome hold-down latches.
• Brakes: only 10.7 % of 1969 Oldsmobile intermediates had disc brakes, according to Car and Driver.

The full 4-4-2 history covers the big-engined sister car, the Oldsmobile catalogue lists the Cutlass range, and the W-31 is one of the small-block cars in the muscle car guide.