The roots of today’s pushrod engines stretch back to the post-war years.
Contemplating the advantages of the pushrod-actuated overhead valve engine design in what appears to be the twilight of internal combustion might sound as anachronistic as a quick look at the value of coal-fired steam locomotives.
But design advances in these engines, particularly the larger-displacement V8 variety beloved by American drivers and automakers alike, mean that these engines boast advantages that seem certain to keep them relevant until the very end of combustion power.
Let’s start with some definitions. Overhead valve pushrod engines marked an advance over their predecessors, the flathead engines whose valves are located in the engine block alongside the cylinder. The Ford flathead V8 and the classic Briggs & Stratton power equipment engine are well-known examples.
These engines are compact, inexpensive to manufacture, and woefully inefficient because of poor airflow, combustion, and thermal characteristics. Flathead engines’ combustion chamber is wide and flat, covering the piston top and the valves, making combustion very ineffective. Consider it the opposite of the concentrated, semi-circular combustion chamber shape of the Hemi engines we discussed previously.
Additionally, the airflow into and out of the combustion chamber is indirect, as the air must make hard 90-degree turns. And the intake and exhaust ports are located adjacently on the same side of the cylinder, transferring exhaust heat to the intake charge, reducing its density and resulting power.
Success has many fathers. Failure is an orphan. Lee Iaccoca made sure everyone associated him with the success of the Mustang, but who is to blame for the Edsel? Digging into those stories illuminates business culture even today.One interesting anecdote, largely unexplored, is the question of where the American Motors Corporation V-8 that debuted in 1956 came from. AMC only came into existence when Nash and Hudson merged in 1954.
Neither marque previously had a V-8, though Nash had long used overhead valves. Hudson was well known for its powerful flathead straight-sixes. To compete in the mid-’50s, though, a company absolutely had to have a V-8.At first, it appeared that the solution was to purchase Packard’s new V-8 engine, which had debuted for 1955. A detuned version was available in both the Nash Ambassador and the Hudson Hornet for 1955 and part of 1956.
Unfortunately, the arrangement between the companies broke down, leaving AMC to fend for itself.In a remarkably brief time, AMC replaced the Packard engine with its own design, a 250-cu.in. V-8 that grew to 327-cu.in. by 1957, when it made a big splash under the hood of the compact-sized Rambler Rebel.
The Rebel wound up being the fastest American sedan that year—beating out the likes of the supercharged F-code Ford, the fuel-injected Chevrolet, and even the vaunted Chrysler 300C.
Excerpt from Jeff Zurschmeide’s Flathead V8 article on enginelabs.com
In the history of automotive engines, it’s impossible to overstate the importance of the V8 design. By dividing the eight cylinders into two banks of four, engineers achieved a powerful, yet compact unit that could fit into the vast majority of engine bays also sized to fit four or six-cylinder engines.
Ford did not invent the V8 engine, but it can be fairly said that they brought it into everyday use. Some European marques and Cadillac had V8 engines decades before Ford developed the engine that would yield affordable performance and create the basis for hot rodding