Having acquired your engine and before beginning any work, it would be advisable to try to track down a manufacturer’s instruction book for it. Fortunately, photocopies are generally available for most engines, and if not, a bit of time searching the Internet might identify a fellow enthusiast who will provide a photocopy at cost. These books or pamphlets give basic instructions for setting up and starting the engine. They also have a list of parts and, in most cases, rough illustrations of the parts and assembly.
Once you have your engine home and have examined it thoroughly, your first decision is to decide on the type of restoration you want to undertake.
Restoration categories
Restoration can be divided into three broad categories:
- Minor
- Partial
- Complete rebuild
A minor restoration might be as simple as replacing a broken sight feed oiler or fitting a new ignition lead. Once this is done, all that is needed is to check the oil and grease, etc., before filling with fuel and starting.
A partial restoration might involve stripping one or more of the main components before replacing or repairing a few minor parts.
A complete rebuild is just that: full disassembly and a top-to-bottom repair with the replacement of some major parts.
Another key decision is whether to refinish and repaint the engine. This subject has been, and will continue to be, a major source of debate. In my view, the engine should be kept as original as possible. Having said this, if the engine acquired has been so badly rusted, or painted in the wrong shade or color, there is nothing else that can be done except repaint it.
If an engine is complete and still has traces of the original paint, then it is best to leave it “as-is,” and clean off the surface rust while enhancing any remaining paint color and protecting the exposed metal against further corrosion. This can be achieved by making up a 50:50 mixture of boiled linseed oil and white spirit, which can take several days to dry once applied. Do not use this mixture if you will later want to re-paint the engine as it is difficult to remove, particularly where it has flowed into rust pitting.
An alternative is the proverbial oily rag, which is just as effective but will need to be repeated from time to time and also has the habit of rubbing off on your clothes. There are also some good anti-rust oils available, but do not use WD-40 since it only removes water and has no lasting anti-rust properties.
It might be necessary to replace parts, and this, coupled with the need to halt any further erosion of metal, means it is easier to prime, paint and refinish the engine as new. Of course, any new parts could be rusted and aged to match the rest of a pitted engine. This can be achieved by coating with nitrogen fertilizer and wetting, or painting with vinegar then leaving to rust in damp conditions, but this is a bit extreme.
In cases where new parts are required, it is best to try to restore the engine to look as it did when it left the factory. This means trying to achieve the same color and standard of paint finish as the original. Faithfully follow the original paint color and the lining scheme used, and do not go overboard by highlighting or lining every letter or feature of the engine.
Restoration tools and equipment
Of course the amount of restoration undertaken depends on your facilities and space available in which to strip and repair an engine. The car might have to be evicted from the garage, or alternatively a large shed is an ideal acquisition. The level of workshop equipment that you have at your disposal is also a major consideration, particularly if you want to undertake some machining.
At a minimum a good set of hand tools is required, in particular the correct size wrenches for the type of engines you intend to strip. Most of the old engines have large dimension hexagon nuts and bolts, and while adjustable wrenches can be used, there is nothing to beat the correctly sized wrench, both open ended and closed, for those awkward nuts.
Farm sales are good sources of old tools that are normally not wanted by other bidders, and you can never have too many wrenches, even of the same size!
A set of socket wrenches is useful and a dead blow hammer always comes in handy with a few brass drifts. A propane gas torch can be useful for heating parts for their disassembly, subject to some restrictions on the use of heat.
Naturally, an assortment of files is essential, in various sizes, profile and cut (bastard, second and smooth) with a good engineers’ vise, secured to a solid work bench.
As a member of an engine club or restoration group, you will soon find people who are willing to help with the loan of other tools as well as providing advice or even assistance. While a workbench is needed for working on parts, some form of stand is useful to keep the engine at working height to keep from continually bending over. Some form of hoist or lifting equipment will be needed to get your engine on the bench unless you are only repairing a small one that can be easily manhandled.
In terms of workshop equipment, there are certain basic essentials, but beyond these, it is a case of what needs to be done and your level of confidence in undertaking more complex tasks. For example, it is no good buying a welding kit if you are not confident enough to use it effectively — far better to find someone skilled to undertake this task for you and in the process get a first-class weld.
A well-equipped engineer’s workshop is a definite advantage. A lathe and mill mean that some parts can be made or re-finished rather than trying to find original spares or buying modern replacements.
Taps and dies are always useful to re-cut and renew damaged threads, but good ones are not cheap and you might be able to find a friend or member of the engine club who will help you out.
Some old engines are heavy and a rolling bench is useful in the workshop so that you can easily move the engine around. A simple one can be easily knocked together from some lengths of wood and old casters.
Depending on the size of engine that you intend to restore you might need some lifting equipment, the simplest being a chain hoist secured to a roof beam, providing it is strong enough to take the load, or alternatively a movable engine crane. This can be handy not just to lift the engine but also to steady flywheels and heavy parts during assembly.
To preserve your good name I recommend that you document any repairs or replacements you carry out so that if you later sell the engine you can pass a copy to the purchaser. If, in the future, any issues arise from someone passing off an engine you rebuilt as “all original” you have the evidence of the true state of the engine when you sold it. In order to document your restoration, a digital camera is useful so that photographs can be taken at each stage. Photograph parts before and after restoration as a record.
Once your latest purchase is home, your first instinct is to try to start it straight away. If the engine has been acquired from a known and reputable source, then any assurances regarding condition and running can be relied upon. Otherwise, before attempting to start the engine by turning it over, there are a few important checks to carry out in order to try to prevent any prospect of further damage to your engine.
Gas engine pre-start checks
- Check the sight feed oiler drip rate and oil level, and make sure all grease cups are filled/tightened and other lubrication points are oiled.
- Examine the general movement of parts while holding the inlet valve open. At any sign of scraping, grinding or excessive looseness, further investigation is required to prevent major damage.
- Release the inlet and exhaust valves to check if they move freely; then check the compression.
- Check all visible nuts to ensure they are tight. If the visible nuts are not tight and you are suspicious that the engine has been partially stripped, then all nuts and bolts must be checked over, stripping the engine if necessary.
- Examine the operation of the inlet and exhaust valves, and free up any pushrods and levers. Check the operation of any pumps for free movement; examine and lubricate any gland packing, and check the presence of and free movement of check-balls.
- Check the governor linkages, weight movement and spring quality, and that all pins are oiled.
- Check the igniter, if fitted, to make sure it snaps and gives a spark when connected to a battery and coil. Clean any sparkplugs and measure the gap, ensuring that there is a strong spark by grounding the plug lead while turning the engine.
- Check for blockages in the water lines, fuel lines and tanks, and clean any dirt before filling. Dispose of old fuel in an approved manner before filling with fresh clean fuel.
Running your has engine for the first time
Starting the engine should then follow the manufacturer’s guidelines for the opening of the mixer valve, etc., which will be set out in the engine manual. If in doubt where to locate a manual, search the Internet or ask your engine club.
While the engine is turning over, listen for any strange sounds. If there is any knocking or other suspicious noise, shut down immediately by turning off the fuel or disconnecting the ignition. If an examination of the exterior shows nothing apparently wrong, then you will have to start stripping the engine.
This article is an excerpt from Gas Engine Restoration: A Practical Guide for Beginners and Experienced Collectors. Author Peter Rooke is a regular contributor to Gas Engine Magazine and wrote a follow-up book titled More Gas Engine Restoration: Restoration Techniques and Tips for Beginners and Experts.
Originally published as “Before Starting” in the August/September 2023 issue of Gas Engine Magazine.
