General Motors has developed countless V8s over the years, but maybe the most unusual was the 1930-32 Oakland/Pontiac Eight.

The 1930 Oakland Eight wasn’t the General Motors division’s first V8. Back in 1916, Oakland offered a 365 cubic-inch L-head V8 in its Model 50 line. Manufactured by Northway, another GM subsidiary, it met with some limited success. When Oakland returned to the V8 configuration in 1930 it was with a totally different engine, and it was a remarkable one, designed by chief engineer Benjamin H. Anibal.

In Motor City lore, the 1932 Ford is often said to be the first monobloc V8—that is, with its cylinder block cast in a single unit. Actually, Oakland introduced a monobloc V8 two years earlier, but it wasnt’t the first, either, nor was GM’s Oldsmobile Viking in 1929. (See our Viking feature here.) While the Oakland and Viking V8s share similar design features, they are different engines that share no major components.

With a slightly oversquare bore and stroke of 3.4375 by 3.375 inches, the new V8 displaced 251 cubic inches and was rated at 85 brake hp at 3,200 rpm. All fairly conventional so far, right? But from there the Oakland is a departure in a number of ways. For example, note the staggered bore spacing between the center cylinders and the large chest cast in the top of the block to house the horizontal valves.

Another unconventional feature for 1930 was the single-plane aka 180 degree crankshaft. Fully counterweighted with three main bearings, it weighed 58.5 lbs. In 1924, Cadillac had introduced the crossplane or 90 degree crankshaft, solving a significant problem with early V8s: a second-order horizontal shake that produced excessive vibration for the driver and passengers. In that regard the Oakland V8 was a step backward, but here the engineers came up with an alternate solution.

The horizontal-valve layout was used on a few L-head engines in the 1930s, including Auburn, Cord, and Packard (see our features on the Auburn here and Packard here). This design allowed a more compact combustion chamber than a conventional L-head without the added valvetrain noise and complexity of an overhead-valve setup. The Oakland design added an extra wrinkle: the cylinder heads and deck were machined in two planes, with a metal one-piece gasket that bent into place when the head was torqued down.

Oakland’s solution to the flat-crank shake was an articulated engine mount called the Synchronizer, developed and patented by GM research engineer Caleb E. Summers (above). A four-lobe cam ran at half engine speed from the camshaft, operating a lever with its fulcrum down near the crank centerline.

The lever, in turn, drove a spring-loaded shaft attached to the leaf-spring engine support. As the engine shuffled to the left and right with the crankshaft’s reciprocating force, the synchonizer pushed back in the opposite direction to counter the motion. A pair of rubber mounts at the rear allowed the engine assembly sufficient movement for the synchronizer to do its thing. The system was effective but mainly at lower engine speeds, while the highly loaded four-lobe cam was subject to excess wear, reportedly.

The brochure illustration above provides another view of the Synchronizer and the horizontal valves and rocker arms. The four-ring pistons were semisteel cast-iron with 1.25-in diameter wristpins and aluminum expansion buttons to lock them in place. Compression ratio was 5.2:1, and this V8 was an early adopter of the downdraft carburetor, here a one-barrel Marvel-Schebler.

At $995 the Oakland Eight was the lowest-priced V8 on the market, but by then the brand was in steep decline and was discontinued at the end of 1931. GM was now pinning the former Oakland division’s future on the more successful Pontiac satellite brand. A revised Oakland V8—mainly, the synchronizer was moved to the opposite side—was adopted by Pontiac for 1932 (below), but it was dropped after one year. Pontiac would return in 1933 with an eight-cylinder engine, but it was a conventional straight eight.