Hercules Gas Engine Restoration

Peter Rooke tackles a circa-1923 Hercules Economy Model F gas engine.

| August/September 2015

  • Hercules engine
    The circa-1923 Hercules Economy Model F.
    Photo by Peter Rooke
  • Damaged flywheel hub
    The damaged flywheel hub, with broken section clearly visible.
    Photo by Peter Rooke
  • Pulling sprocket
    Pulling the sprocket was made easier with a hydraulic puller.
    Photo by Peter Rooke
  • Flywheel hub after cleaning
    The flywheel hub after cleaning, with the blowhole clearly visible.
    Photo by Peter Rooke
  • Broken flywheel hub piece
    Broken flywheel hub piece cleaned, grooved and ready for welding.
    Photo by Peter Rooke
  • The blowhole filled
    The blowhole in the flywheel filled.
    Photo by Peter Rooke
  • Tack welding the flywheel hub
    Starting to tack-weld the broken hub piece to the flywheel.
    Photo by Peter Rooke
  • Repaired flywheel
    The finished repair to the flywheel, welded and filed back to shape.
    Photo by Peter Rooke
  • Old pushrod
    The old pushrod. Bent and twisted, it had seen better days and had to be replaced if the engine was going to run well.
    Photo by Peter Rooke
  • Milling the slot
    Milling the slot for the catch plate in the new pushrod.
    Photo by Peter Rooke
  • New pushrod on lathe
    The pushrod set up on the lathe to turn the front end.
    Photo by Peter Rooke
  • Pivot and exhaust valve
    Pivot and exhaust valve arm before welding.
    Photo by Peter Rooke
  • Rocker arm almost complete
    Fabricated rocker arm almost completed.
    Photo by Peter Rooke
  • Finished rocker arm
    The finished rocker arm, complete except for drilling the oil hole.
    Photo by Peter Rooke
  • Cylinder head removed
    The cylinder head as removed from the engine. The valve guides and stems were badly worn.
    Photo by Peter Rooke
  • Old valves
    The old valves after removal, with stem wear clearly evident.
    Photo by Peter Rooke
  • Valve head and stem separated
    A valve head and stem separated.
    Photo by Peter Rooke
  • Reaming valve guides
    Reaming out the valve guides for the larger valve stems.
    Photo by Peter Rooke
  • Cutting off valve head
    Cutting off the head of an old valve on the lathe.
    Photo by Peter Rooke
  • Valve heads brazed
    The original valve heads brazed to new stems. The stems were also peened over as a final step.
    Photo by Peter Rooke
  • Refurbished cylinder head
    The refurbished cylinder head. The intake and exhaust elbows were left as found.
    Photo by Peter Rooke
  • Governor pivot pins
    New and old governor weight pivot pins.
    Photo by Peter Rooke
  • The governor assembled
    The governor assembled with new pins in place.
    Photo by Peter Rooke
  • New speed adjustment arm
    The new speed-adjustment arm.
    Photo by Peter Rooke
  • Speed adjustment arm
    Speed-adjustment arm in place with new pivot pin for detent blade holder being installed.
    Photo by Peter Rooke
  • Cleaning taper on mixer needle valve
    Cleaning up the taper on the mixer needle valve. A tapered reamer the same profile as the needle was used to cut the seat.
    Photo by Peter Rooke

  • Hercules engine
  • Damaged flywheel hub
  • Pulling sprocket
  • Flywheel hub after cleaning
  • Broken flywheel hub piece
  • The blowhole filled
  • Tack welding the flywheel hub
  • Repaired flywheel
  • Old pushrod
  • Milling the slot
  • New pushrod on lathe
  • Pivot and exhaust valve
  • Rocker arm almost complete
  • Finished rocker arm
  • Cylinder head removed
  • Old valves
  • Valve head and stem separated
  • Reaming valve guides
  • Cutting off valve head
  • Valve heads brazed
  • Refurbished cylinder head
  • Governor pivot pins
  • The governor assembled
  • New speed adjustment arm
  • Speed adjustment arm
  • Cleaning taper on mixer needle valve

This is part 1 of Peter Rooke's series on restoring a circa-1923 Hercules Economy Model F engine. Continue reading in part 2.

Hercules background

Another tired old engine has joined my collection, a circa-1923 Hercules Economy Model F, serial number 290,884. The Economy engines were first made in Sparta, Michigan, by the Holm Machine and Manufacturing Co. for Sears, Roebuck & Co. By 1912 Holm could not keep up with demand. The Hercules Gas Engine Co. was formed that year, having purchased Holm and started work building a new factory in Evansville, Indiana. The first Hercules produced engines were sold in January 1914 and were known as the Model D. The Economy engine produced for Sears differed slightly in design to the Hercules, having a more rounded lip to the water hopper, no crank guard and being painted red rather than Hercules green.

The Model E was popular, with some 220,000 engines sold. It was followed by the Model F, which was produced from 1921 to 1923. An estimated 25,000 Model Fs were produced that incorporated design modifications including the supply of Webster 1A and 2C magnetos. These magnetos did not prove popular, and many engines were later converted to use either Wico EK high-tension magnetos or fitted with the older Webster oscillating magneto. Looking at what was left of the trip finger clamp on the pushrod on my engine, it would appear it had been converted to run using a Wico EK.

Stripping

From looking at photographs I received before purchasing the engine, I knew numerous parts were missing, including the muffler, igniter, magneto, rocker arm, fuel tank and fuel filler spout. There was a large toothed sprocket fitted to the crankshaft, and I was advised that this probably was used in a cement mixer. Hercules sold engines to Jaeger to use on cement mixers, so before doing anything I carefully examined the side of the engine casting to see if I could find any holes where another nameplate might have been fitted. There were none.



The entire engine was covered in rust and there was some bad pitting to the flywheels. Grease around the crankshaft bearings had protected the paint in that area and there were specks of red paint still showing. That suggested this was an Economy engine.

After using the hoist to get the engine on the workbench, the first task was to remove the sprocket and examine the crack at one end of the flywheel hub. The sprocket proved to be stubbornly in place. After applying plenty of lubrication, a hydraulic puller was used to remove it.



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