1962 Pontiac Tempest

It Has Arrived

            This car was put together by Bud Stump out in California and we do not have the precise date as this project was little publicized.  Stump was mentioned a few times in the steam publications.  He had been part of the early 1950’s McCullough-Paxton steam project that was engineered by Abner Doble and was his last big project looking for the ultimate in steam automobile efficiency.
  1962 Pontiac Tempest Steam Car
   

Caption for photo above: The car recently delivered to the property of Jim Tangeman in Oroville, California.  We do not know much about the car’s history, except that it had spent a lot of time sitting outside under a tree and, because that was in Portland, Oregon, it was in the rain.  The convertible top had rotten away, the upholstery was gone but the trunk lid was secure and solid protecting the boiler and its controls.  New rubber had been mounted so that the car could be hoisted onto a trailer.  While awaiting transportation to Michigan two Soule engines, made by the Soule Steam-feed Works, out of Meridian, Mississippi are in front of the Pontiac.  These are unrelated to the Pontiac and only coincidentally unloaded where they could be photographed. 
            The two engines in front are the Spee-d-twin engines and a very practical steam engine that is a real steam hog, which does not matter most of the time as they are used intermittently and enjoy immense practicality.  These are set up with 100% cut-off, meaning that they are operating at full boiler pressure all the time, meaning full torque is always available.  Being a double-acting twin on a 90 degree crank they are self-starting.  The reversing system is not the standard Stephenson valve gear but one that reverses the engine by using a push/pull rod that switches the ports inside the valve chest, giving quick stopping and reversing action.  These engines were used a lot on saw mills driving the carriage feed or by rotating the logs ninety degrees for squaring them up prior to sawing boards.  Steam power and this type of valve gear were the only practical way of achieving this flexible power source with full torque all of the time in the years before diesel engines, hydraulic pumps, hydrostatic motors, and cylinders were invented.  Even after electricity was invented these systems worked maintenance free when the constant switching and starting under full load would wear out an electric motor.

           

   

          (Continued story above:)  The story is that a rich person from Kalamazoo, Michigan funded this car because he wanted a modern steam car.  The boiler was made by George Sanden who had converted a 1953 Studebaker to steam power and it purportedly went fast enough to scare normal people.  A very similar design was used on the Pontiac as Sanden had used on the Studebaker.

            The boiler was a monotube and we think using Besler smoke generator coils.  The engine was a 20 hp Stanley.  The Tempest had independent rear suspension.  It appears to have never been delivered to Kalamazoo.  It ended up in Portland where it sat outside in the rain for five years, thus giving it the recently popular patina of age.  That should increase its value. 

            When it arrives at my shop in the next few months the boiler control mechanism will be studied. It has arrived.

The car after several days of wire brushing to remove rust and scale.  It sits nice on its new rubber.  There are only a few holes in the floor pan.

 

 

  Sideview

 

View of the horizontal boiler, which is technically a steam generator as boilers are a large pressure vessel that has potential to blow up.  This is looking into the trunk from the inside of the car.  The controls and burner are best seen from the back of the car.  It is the classic monotube using more or less the Doble design for the pancake and helical coils and quartz rod control system.

 

 

 

            View of the inside floor board of the car with the seats out.  Engine is the classic 20 hp Stanley, two cylinder double acting 4” bore and 5” stroke slide valve and Stephenson reversing link that also acts as a cutoff control.  This Pontiac Tempest was chosen because it had independent suspension, meaning that the original differential and integral transmission were bolted to the floor boards.  The stub axles were affixed to the suspension, thus greatly reducing unsprung weight.  The Stanley engine, as mounted in a Stanley automobile, is supported in the front by a ball, fitted into a socket, so that it can move up and down and rotate with the rear axle.  The original Stanley-made Locomobile had a chain drive from the engine to the axle.  This arrangement had been patented by the Stanleys and then sold to the purchasers of the Locomobile company, thus they had to come up with another way of transmitting power from the engine to the wheels, hence the straight cut spur gear on the engine meshing with the same style of gear teeth cut into the ring gear of the differential.  This was a long way around the barn to making a steam powered car with good suspension by minimizing the unsprung weight. 
            There have been no mass produced steam automobile engines and so when first working with modern steam power, the inventors/developers used existing Stanley or Locomobile engines and in a few cases Bryan Steam tractor engines.  The best made from scratch auto steam engines were the Charlie Keen and Williams Brothers engines from the mid-1950s.  These were both one off designs.  I should mention the Leslie in-line six from the late 1930s as being one of the best designs ever and also the Besler designed Kaiser Manhattan V-4 steam engine from the 1960’s—again one-off designs.  We hear rumors that Derr made a very nice V-4 steam engine, but that has been lost in the mists of time.

Boiler in the trunk section

Backview

 

 

These are photos of the controls for the monotube boiler that was made by George Sandin of Northern California.  It is identical to the boiler he made for his Studebaker, likewise with a Stanley engine in it.  You will notice the various temperature sensors—expanding rods, and the pressurestat—a Bourdon tube.  There are numerous holes in the bell cranks for adjustment as experience was gained with this boiler.  If you know what to look for you can see in the top right corner of H four microswitches that are actuated by a lever that moves across them. 
In an automobile, steam demand is continuously variable depending on traffic, hills, speed limits, and stop signs, making it very complex to control a boiler.  Boiler control is always aimed at a constant steam pressure and steam temperature.  Basically, steam temperature is controlled by input water flow (more water cools it) and steam pressure is controlled by burner heat production.  Usually, with an atomizing gun-type burner, there is no modulation of the fire—it is only on and off.  Sandin had a two speed burner control in his Studebaker with the lower output for city driving and the higher output for highway speeds.  Anyone who has worked with a monotube steam generator will state that it is a miracle if there is any control at all with a monotube as hunting, flooding the boiler, and running it dry are the usual. 
The reason is because there is a several hundred foot length of tubing between the cool water input and the hot steam output, giving many opportunities for hysteresis.  Ideally, reading output steam temperature should give one good control.  In reality, by the time the cool input water traverses the many feet of tubing to get to the end where the steam temperature is used to control the water flow, the boiler is flooded which starts a great oscillation of steam temperature almost impossible to stop. 

Above: shows the end of the burner can—air fed in by a squirrel cage blower, spark plug ignition.

Above: shows the bourdon tube and solenoid that controls water flow, with the burner can barely showing at the far right.
 
     

 

  Engine