5 Mystery Muscle Motors of the 1960s that Detroit Never Sold in a Car

Updated September 18, 2018

Overhead camshaft engines are commonplace today, but Detroit has been tinkering with OHC V8s since the ’60s. While some of the most iconic engines of all time were those that made their way into production cars of the ’60s, it’s highly likely that you’ve never heard of any of these high-horsepower beasts.

From experimental designs to beefed-up takes on existing motors, this group will surely make you wish some of these engines actually made production, as each is more impressive than the last! Click ‘Next’ to view our list of 5 monsters never sold to the public.


1968 Ford 289 SOHC V8

Ford built three experimental 289 with a unique single overhead camshaft design that features a cam located in each of the cast aluminum valve covers (instead of on top of the cylinder heads). The lobes of each cam activate the cast iron rocker arms that open each valve. In the original camshaft position within the engine is smooth shaft whose role is to drive the distributor as well as the two overhead cams. The purpose of this project was to raise the maximum engine speed and with it peak power. The OHC 289 produced 300 HP at 6500 rpm.

Ford considered offering the SOHC conversion as a kit. But as the stock HiPo 289 already made 271 hp, and Shelby was getting 306 hp with bolt-on parts, it was deemed not worth pursuing.


Oldsmobile W43 DOHC V-8

As part of the development of the Oldsmobile 455, Olds engineers wanted to take the design of the engine as far as possible. The ultimate version added a set of dual overhead camshaft cylinder heads to the mighty engine. A gear drive supported by roller bearings in an aluminum gear case at the front of the motor spun the cams, while a driveshaft was used in the standard camshaft position to transmit motion to the oil pump and distributor.

Toward the end of 1969 engineers dyno tested the DOHC W43, built with a very racy12.2:1 compression ratio, and recorded a very flat (and fat) torque curve. Peak power Olds engineers recorded was 700 horsepower at close to 7000 rpm. This was achieved using the standard cam profiles for the W43, ground onto separate intake and exhaust camshafts. At that point, no development had been done to optimize cam specifications to match the breathing of the heads.

But on January 1970, General Motors President Edward N. Cole  announced that all GM divisions would lower the compression of their motors so 91 octane unleaded fuel could be used, and development stopped on the DOHC Olds.



1964 Pontiac SOHC V8

Most likely prompted by its development of the Pontiac OHC six, the GM division built three different experimental SOHC 421 CID V8  engines in the early 1960s. According to the engineers who worked on the project, the SOHC 421 engines produced around 625 hp and were capable of turning 7,000 rpm.

One version of the engine featured camshafts driven off the front of the engine, another design had the cams driven by gears off the back of the engine.  Apparently at least one of these engines survives under the hood of an engineer’s personal Pontiac.



1967 Cadillac Eldorado V12

As part of the General Motors V-Future program, Cadillac developed an overhead cam V12 slated for production in the late 1960s. The V12 engine was to make its debut in the new FWD Eldorado in 1967.

Six prototypes engines were built in 1963 and 1964, all with a 60-degree architecture, chain driven overhead camshafts and hydraulic finger followers. The initial displacement was 7.4 L, but an 8.2 L was also tested. A number of different induction systems were tested, including a single four-barrel, dual four-barrel, and triple two-barrel carburetors, as well as mechanical fuel injection. Output ranged from 295 to 394 horsepower.

Based on the power output listed above you can see why the Cadillac V12 program was killed. Not only was horsepower disappointing, but GM was also concerned about the engine’s ability to meet upcoming mandated emissions controls.



1969 Plymouth Weslake DOHC V8

It’s unknown whether this project was purely for racing, or Plymouth had the intent to offer the motor in a street car at some point. Keep in mind that the entire Chrysler group witnessed the excitement and positive impact on the brand when the previously race-only 426 Hemi was offered in production cars.

Following the 1968 season, Richard Petty announced he was leaving Chrysler and going to Ford for the 1969 NASCAR season. The money allocated for Petty was used to develop the Plymouth Indy DOHC V8. Design work began in February 1969 and running engines were provide to Andy Granatelli’s STP race team less than 90 days later.

The designer of the special cylinder heads was Harry Weslake, a British engineer best known for his expertise in gas flow through internal combustion engines. If you recognize the name, it may either be for his V12 engine in Dan Gurney’s 1967 Belgian GP winning Eagle, or the Gurney-Weslake cylinder heads used on GT40 Fords.

The engine lacked top-end horsepower necessary to compete at the high speed oval tracks, it had plenty of bottom-end torque which made it quite competitive on the short oval. In fact, Art Pollard drove the Plymouth-Westlake engine to victory at the 200-mile Indy car race at Dover, Delaware on August 24, 1969. This would turn out to be the only victory for Plymouth in the history of Indy Car racing.



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Chris Riley
About Chris Riley

I have been wrecking cars for as long as I've been driving them but I keep coming back for more. Two wheels or four, I'm all in. gives me a chance to give something back to the automobile community.

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