The 1968-1970 Oldsmobile 350 CID W-31 V-8: The Little Engine that Could!

1968-1970 Oldsmobile W-31 Facts – The Oldsmobile Gen 2 330-350 CID small block was capable of exciting performance from it’s outset, but when equipped with the W-31 option – WOW!

How the “economy” V-8 from Oldsmobile became a race legend.

1968-1970 Oldsmobile W-31 Facts

Lots of people think the “Ram Rod” 350 CID V-8 was spawned from the outstanding success of the powerplant’s 330 CID version in the 1964 442. And while it certainly perked up the ears of the hot rod crowd with its outstanding performance in Oldsmobile’s version of mid-size muscle, it soon was relegated to making Cutlasses and F-85s perky. When the 400 CID V-8 for the 442 arrived, all attention went to the 400 CID big block.

Olds engineers were quite proud of the 330’s ability to make some good HP and wind up without throwing a connecting rod. Other than that, it seemed like the motor would be a sidebar, no matter what they thought.

Meanwhile, the world was going race car crazy in the 60s and a many new race series were spawned, most notably in the SCCA, with American V-8s in whatever race chassis you could scare up – from European to backyard babies. These series started with 5 liter (302 CID) then then a 6 Liter (366 CID) limitation. Stock blocks were required, but modifications were unlimited, except for sophisticated aftermarket cylinder heads.

1964-65 McLaren M1A Oldsmobile

Fitted with an Oldsmobile engine, this Elva-built McLaren M1A was sold new to American privateer racer Ralph Salyer. The car was also referred to as the ‘Cro-Sal’ special to recognize the efforts of Salyer’s longtime mechanic Gene Crowe. Behind the wheel of this McLaren, Salyer was among the quickest drivers in 1965 and convincingly clinched the pole position in the SCCA National Championship run-offs at Daytona. Salyer would later replace the  McLaren chassis with a McKee chassis and to some extent, a partnership was formed.  In ’66 their engine of choice was Chevrolet, but that would soon change.

Going backwards a bit, the love affair with Salyer, and to some extent, McKee started earlier on when they chose the Buick/Olds aluminum 215 CID V-8 bored and stroked to 300 CID and fitted with the Oldsmobile heads because Olds used a 6-bolt head fastener, rather than the Buick’s 5. When the CID limit was changed to 6 Liters, the block was retired, and Chevrolet power was fitted.

1964 Oldsmobile Small block Arrives

The 1964 Olds 442 proved itself to be more than able even when only fitted with the 330 CID V-8.

In 1964 Salyer returned to the new Oldsmobile block.While the car was reasonably successful, there just weren’t enough speed parts for the engine. But during 1965 and early 1966 big block heads were fitted. (In case you don’t know, Olds small and big block engines differed mostly in deck height and crankshaft dimensions, so parts could be exchanged). This improved performance, BUT low end torque was almost nonexistent.  In 1967, Dale Smith, who was in charge of Olds engineering and managing the 442 program, suggested that 1967 330 CID heads should be fitted with the 400 CID’s valves, a simple, almost backyard fix.

The results were astounding, with the 330 motor making 1 HP per CID in almost stock form, and well over 400 when modified! Unfortunately, the SCCA Series went to Group 7 (7 Liters), and that set the stage for the big block Chevrolet.

But back at Oldsmobile, Marketing and Engineering were noticing that Chevrolet’s small block had quite a following in their mid-sized cars, because, in a great part of cost and drivability. The stage was set. Know this, Oldsmobile knew that their soon to be released 350 CID V-8 could be a winner. And before it was launched they saw that it would fall neatly into E/S at NHRA. What they also knew was that the lighter engine in the Cutlass using 442 suspension, would be a great handler – not to mention that it would be less expensive than the 442. (Even then there was an insurance penalty for cars with over 400 HP).

Let’s view the specs:

Cast iron block. Displacement: 350 CID.
Bore and stroke: 4.057″ x 3.385″.  Five main bearings.
Compression ratio: 10.50:1.
Horsepower: 325 @ 5400 RPM.
Torque: 360 @ 3600 RPM.
Valve Head Size (intake) 2.003″-1.990″; (exhaust) 1.629″-1.619″.
Hydraulic valve lifters.
Camshaft: Duration: Intake 308°, Exhaust 308°, Overlap 82°, Lift (intake) 0.474″, (exhaust) 0.474”.
Carburetor: Rochester Quadra-jet 4-barrel, 1968: (manual transmission only) 7026825O/55; 1969: (manual & automatic transmission) 7029255; 1970: (manual & automatic transmission) 7040250.

Two things should stand out: the big block valves and the 1966-67 big block W-30 camshaft were used. That horsepower figure has been confirmed by many tests including this one: https://www.youtube.com/watch?v=rZQ55ee_XDY&t=1s . But Oldsmobile cheated by rating the engine at this lower RPM, because the engine’s HP potential actually started to climb after 5400 RPM, with fully race prepped engines developing well over 400 HP at over 6500 RPM. These figures can be confirmed by the ¼ mile elapsed times in the 12.5 second range!

Ron Garey besting John Dianna in Stock eliminator.

The car was a killer in its NHRA class for all 3 years it was produced, including stock Eliminator at the 1968 Springnationals. (1968 NHRA Records: E/S 12.70 1968 Oldsmobile Cutlass “Ram Rod” 350/325 HP, E/S 107.65 1968 Oldsmobile Cutlass “Ram Rod” – 350/325 HP).

And a W-31 was taken to Bonneville where it captured class record speeds that stood for many years.

Here are some back in the day tests that will tell you how enthralled journalists were with the W-31:

• • 1968 Oldsmobile Trio Test – Including the W-31 – Click HERE.
  • 1968 Oldsmobile W-31 Road & Drag Test – Click HERE.
  • 1968 Oldsmobile W-31 Build and Test in Three Parts – Part One HERE, Part Two HERE, Part Three HERE.
  • 1969 Oldsmobile W-31 Road Test – Click HERE.
  • 1969 Oldsmobile W-31 Road Test – Click HERE.

And for those of us that have owned a W-31 (this author has owned three), you wouldn’t find a more willing performer. For whatever the reason, low speed torque was always available, it was happy to cruise even with 3.90:1 rear gears, and when the hammer was dropped, it could storm!

Here’s a teaser for you. The Olds Small Block Can Am motor as displayed back in 1962. It was offered in 366 or 383 CID via overbore and stroker crank.

This image is downloadable in PDF HERE.

A Brief Set of Specifications for The Gen 2 Oldsmobile Small Block

1964 Oldsmobile 330 CID Engine Specifications
Click the tabs for specific engine information

1965 Oldsmobile 330 CID Engine Specifications
Click the tabs for specific engine information

1966 Oldsmobile 330 CID Engine Specifications
Click the tabs for specific engine information

1967 Oldsmobile 330 CID Engine Specifications
Click the tabs for specific engine information

1968 Oldsmobile 350 CID Engine Specifications
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1969 Oldsmobile 350 CID Engine Specifications
Click the tabs for specific engine information

1970 Oldsmobile 350 CID Engine Specifications
Click the tabs for specific engine information