Part One in a Five-Part Series: Restoring an Amanco 2-1/4 HP Hired Man
Editor’s note: This article is the first of a planned five-part series by British engine enthusiast Peter Rooke on restoring an Amanco 2-1/4 HP Hired Man stationary engine.
I arrived home with my first stationary engine to be greeted by my wife’s unhelpful comments about a lump of rusty old metal and questions about my sanity. She found it difficult to visualize the mound on the garage floor could eventually become a restored, gleaming, working engine: It would take me almost a year to complete.
I have always been drawn to stationary engines at agricultural events and fancied the challenge of renovating one. I put out the word among farming friends that I was looking for a full-size engine and was soon introduced to an enthusiast at a local show that resulted in an offer of a Lister to restore.
A visit to “Aladdin’s Cave” revealed an amazing collection of over 30 engines. He dragged out a Lister D, and Wolsey WD2 for me to consider restoring. While I was drooling over these he mentioned he had an open crank engine, but it required a considerable amount of work. He then produced a rather tired and rusty Amanco Hired Man. This was it, just what I wanted, small enough for my workshop and a real challenge to get running again. However, the scale of the work required was not really apparent until I had it home.
The Amanco is a 2-1/4 HP Hired Man, serial no. 129028. Depending on which table you read, the engine was made between 1914 and 1916.
The steps I have taken to restore this engine are those of a “first timer” and more experienced enthusiasts might well have had a different approach. For some of the restoration I chose to make new components, as I enjoy working metal. However, time would have been saved and my life made easier if I had sourced the parts from shows and other enthusiasts.
Before starting to strip the engine I followed the advice of others to soak it in oil. I cut a big plastic drum in half, immersed the engine in a mixture of diesel and old oil, and left it to soak for two months, inspecting weekly to brush the dark mixture over any exposed parts.
Eventually I drained off the dirty oil and dragged the engine into my workshop, ready to begin the serious stuff. Washing with paraffin and scrubbing with a wire brush, I started to clean off the accumulation of grime and rust. The full extent of the restoration work required soon became apparent.
While some nuts were removed easily, a liberal application of penetrant was necessary on others. Even after leaving this to penetrate for some time, an igniter stud broke when modest pressure was put on it with a spanner.
The cylinder head was removed first and the work required was clearly evident with a broken end to the exhaust rocker arm, valve stems seized into broken seats and new springs needed. An earlier repair to the post for the exhaust rocker was also clearly visible.
I attempted to free the seized piston but it would not move, despite advice from the vendor that a soaking in oil should do the trick. A length of 3-1/2-inch square oak was fitted in the bore and pounded with a lump hammer, but to no avail; it was stuck solid. Even an attempt to rig a hydraulic gear puller failed to push it out.
It took a visit to a local agricultural engineer and the judicious use of his 10-ton press to remove the piston. Apart from accumulated rust, the reason for the stuck piston soon became apparent. A piston ring had broken and the edge of the piston ring groove was raised. The connecting rod was also bent, with the rust on the big end journal of the crankshaft showing the end cap had been missing for some time.
Removal of the flywheels from the crankshaft also proved difficult. There were no heads on the keys, which were nearly flush with the flywheel hubs. Holes were drilled in each key and threads tapped so that long bolts could be inserted to help pull out the key. There was no flicker of movement and I had to resort to plan B: the use of a hydraulic puller on the flywheel, leaving the keys in place. All rust was wire brushed and cleaned off the crank and a coating of oil was applied. Two pieces of steel plate were fashioned to fit against the hub on the inside of the flywheel and connected by long studs to the puller. The point at the end of the puller was placed in the center hole at the end of the crankshaft and the slack was taken up. After an hour of continuous winding of the puller’s hydraulic screw, and adjusting the length of the studs, the flywheel was removed complete with key. The following day the second flywheel received similar treatment and was successfully removed.
The caps holding down the crankshaft were taken off, the shims being carefully removed from each stud and saved in numbered plastic bags for later replacement. I stripped the remaining components with continued use of penetrant and occasionally a hacksaw.
The engine number was stamped in the end of the crankshaft, but was indecipherable under rust. After several coats of oil and light sanding with medium wet and dry, part of the number could be read with a magnifying glass. Careful work with a fine-point scraper removed some more rust from the number so the shape was visible and the numbers were then enhanced with the application of the correct size of punch.
The drain plug in the cylinder was cast iron and disintegrated when put under pressure with a hex wrench. It was then necessary to use a very small cold steel chisel to remove the rest of the plug from between the threads.
Having removed the various components, the first job was to clean them all up and get the messy stage out of the way. While shot blasting had been suggested I decided to use a steel scraper to clean off the old paint and rust so that I could control how much metal was removed. A scraper can easily be made from an old file by grinding off the serrations, taking care not to overheat the file and lose its hardness.
The cylinder head and igniter studs were very rusty, and were therefore removed, but two broke off making it necessary to drill them out. Not possessing the correct American dies, I decided to use Whitworth tap and dies that are virtually identical apart from the thread form. The threads were then cleaned using the Whitworth taps and a new set of studs were made copying the dimensions of the originals. At the same time 22 new nuts were made from Hexagon bar, of Whitworth dimensions, as the ones removed were damaged or in very poor condition.
Once the cylinder head and main body were clean I used an epoxy filler to cover most of the “orange peel” effect of the rust pitting. The filler was sanded down, but no attempt was made to achieve a perfectly smooth surface, with some dents and ridges being left in order to provide a similar standard of finish to the original. The parts were then given two coats of red oxide primer.
The crankshaft was bent on both sides by 0.006-inch at a point 6 inches from the edge of the web. In addition, the big end journal was badly pitted on one side where the cap at the end of the connecting rod was missing. Fortunately the main bearing areas had been protected by old grease.
The crankshaft run-out could be measured by turning it between centers on a lathe, but this was not possible as my lathe was too small. The second option was to put the crankshaft on V-blocks on my surface plate. Reference points were drawn on the crankshaft with a marking pen at 1-inch intervals from the edge of the web. The V-blocks were placed near the web and a dial indicator was then used to measure the run-out at each point by turning the crankshaft. Care had to be taken not to move the V-block positions on the crank or else the process had to be started again. This was only possible to measure for a short distance along the crankshaft in view of the rust pitting on the exposed areas.
The bent crankshaft and connecting rod led me to believe that someone had tried to free the seized piston by applying force with a metal bar through one of the flywheels. Straightening the crank would not be easy and there was always the risk of irreparable damage. The alternative was to turn it down, but this would result in making bushes for the flywheels and other fittings so I decided to try straightening, as Amanco cranks are very solid castings.
Fortunately, I had access to a friend’s massive press that had once been used by the National Coal Board to straighten girders, which more importantly had a very fine feed to the hydraulic pump so that movement could be controlled to 0.005. After placing the crank on V-blocks between the jaws of the press, a dial indicator was used to measure movement of the crank when under pressure. After the first push of 0.0025, the crank was removed and measured again on the surface plate. After spring back, there was an improvement of 0.0010. This process was repeated until run-out was less than 0.0010, when I stopped, not wanting to risk fracturing the crankshaft.
The local car engineer who reground crankshafts quoted £15 (almost $26) to regrind the big end journal, and he did an excellent job of reducing the diameter to 1.325 inches. The reduction in size did not matter as I next intended to make a new connecting rod and bearings.
Tune in next issue for part two, which will cover the making of the connecting rod, pouring the white metal bearing, machining and scraping, piston clean-up and fitting new rings, and turning the flywheels and pulley.
Contact engine enthusiast Peter Rooke at email@example.com