We came across some information about a very rare experimental engine that Oldsmobile was going to put into production sometime in 1973. One of the members from the forum called Realoldspower.com saw this very rare engine for sale on Racing Junk.com, and provided us with this information. This was Oldsmobile’s first attempt at a real hemi-style engine design, that most people probably never knew existed.

The engine was based off of Oldsmobile’s 455 Rocket block design, although technically it was a one-off design, manufactured to accept Oldsmobile’s real 4 valves per cylinder special hemispherical prototype cylinder head.

This new cylinder head mimicked the Chrysler HEMI design, as such that it had rocker arms that were similar, but the head was of four valve design with two intake valves and two exhaust valves. It was said that when this engine was dyno tested, it produced about 600 horsepower with a stock Toronado intake manifold. This new engine was to be part of an option called the W-43 Performance Package.

Modifications to the original 455 Rocket plant are evident. Combining the most successful top-end design with one of GM's torque-iest engines was a match made in heaven.

Oldsmobile pulled the plug on this engine, probably due to the fact that the gas crisis was just beginning and the muscle car era was soon ending.  This was another case of too much too late, where focus was no on fuel economy and building smaller cars. The engine you see in the pictures is extremely rare, but it is one of the original prototyped engines.

Although it’s not complete, missing pistons, rods, and one cylinder head, it is still a great piece of automotive history. The present owner is looking for $19,000, to take this off his hands, not a bad price if you’re Jay Leno, but for us regular folks we can only hope and dream. On the other hand all this may ever be is just a very expensive paperweight or conversation piece, because without the other, parts the engine could never run again.