Antique Marine Engine Tips

Basic maintenance and operation tips for antique marine engines.

Monarch marine check valve

Monarch marine check valve.

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Antique marine engines are different from the typical two flywheel farm engine one sees at shows all over the country. They are different not only in appearance but also in their operation and adjustment of their moving parts. This is even more so in the two-cycle as distinct from the four-cycle gasoline marine engines.

Before discussing adjustments etc., a few important operational differences should be brought out. In this discussion I am limiting my comments to the early turn-of-the-century small boat engines, the so-called 'one and two lungers.' Not that these remarks won't apply in some cases to the three and four cylinder engines of the pre-WWI and later era. In many cases those engines tended to be derivatives of automobile engines rather than designed from the ground up for marine propulsion.

1. These marine engines had two basic speeds: Idle and Full Speed. The maker controlled the top RPM by the size of the propeller. Due to the limited power available and the design and construction of the hull, the boat was 'pushed' through the water rather than riding on top of the water as with today's so-called planing hull. These two basic facts, available power and hull design, meant that the size of the propeller had to be as large as possible to move the boat in the water against the wind and tide or river current efficiently. The propeller in effect becomes a water pump 'pushing' a stream of water. The 'push' is transmitted to the hull through the rotating propeller shaft pushing against the thrust bearing on the aft end of the engine crankshaft. In turn the thrust bearing transmits the pushing to the engine crankcase, and in turn the crankcase transmits the pushing to the engine bed which is attached to the hull.

2. The size of the propeller served as a limit control or governor on the upper engine r.p.m. Typical r.p.m. speeds for the low speed heavy duty engines used by the watermen in hulls up to about 30-40 feet were in the 300-600 range. The typical pleasure launch of 12 to 20 feet would operate in the 500-700 range, even up to 1000 r.p.m. in some cases. In the earliest years the pleasure launches used the same engines as the watermen. It should be noted up until WW II the propeller r.p.m. for the many pleasure boats remained under 1000 r.p.m., even though their engines may have been operating in the 2000-3000 r.p.m. region. This created a need for a reduction gear between the engine and the propeller shaft or a reduction in propeller size which resulted in less than optimum performance at low engine r.p.m. Approximately 700 r.p.m. was a common propeller shaft speed for many pre-WW II pleasure boats up to 50 feet, and many of these hulls had the classic low r.p.m. engines of the watermen rather than converted high r.p.m. automobile engines. The typical small boat marine engine needed no governor for most operations, so none was provided. There was one operational condition for which one often wished they had a governor and that was when, in heavy swells, the propeller would come out of the water and the engine would tend to race. In 1901 Ray Palmer of Palmer Bros, in Cos Cob, Connecticut, took out a patent on an inertial governor. His patent extended the M/B ignitor trip arm and added an adjustable weight that allowed one to set the rate of ignitor tripping. How successful it was I don't know, and I have never seen any Palmer ad or engine for that matter that had such an ignitor tripper. In the larger engines used on tug boats and big yachts, governors were provided in many cases. When running an antique marine engine without a load one must be careful not to let it over speed, as they can quickly get out of control with possibly deadly results. The typical hit/miss farm engine operating under no load, unlike the marine engine, is controlled by the governor.

4. Essentially all the successful early small boat marine engines mass produced were two-cycle, two-port. The two-cycle, three-port didn't become popular until the Joseph Day, UK patents ran out in the 1906-07 time-frame. A few makers bought licenses, but by that time there were hundreds of two-cycle, two-port engine makers that didn't. It seems as though every little machine shop or foundry was making marine engines if they had a local body of water of sufficient size to warrant tooling up. It is said with a probable ring of truth that the reason Detroit became the automotive production center was that most of the early car makers were using small marine engines in their cars. There were a number of marine engine makers in the Detroit area, and the hollow castings a marine engine water jacket required was a whole new art-form for most foundrymen. It was only natural the marine engine makers by 1905 were switching to making water-cooled automotive engine designs that overcame the speed/weight limitations of the classic two-cycle two-port marine engine.

By 1905 the basic design of the two-cycle two-port was so well imbedded in mass produced marine engines that there were very few changes in the next thirty-plus years. A few makers' designs even lasted in production up until the 1970-90 frame.

Probably the most notable change was about 1909-1910, when the mixing of oil in the gasoline to lubricate the engine was discovered. Up until that time lubrication of two-cycle engines was not very reliable and it was a common practice to festoon the engine with drip oilers and all sorts of lubrication schemes, none of which worked well. Most makers by 1911 would not guarantee their two-cycle engines unless the user mixed oil in the gasoline. Typical ratios were one pint SAE 30-weight oil to five gallons of gasoline. Some makers even put a brass plate on the engine warning to mix oil in the fuel. One point to be made is that many makers would continue, if asked, to supply oilers, etc. but they would not guarantee their engine unless the oil/fuel mix was used. So here is one tip to collectors: don't operate these old timers, regardless of how many oilers may be on the engine, without mixing SAE 30 oil 40/1 in the fuel. Don't use detergent oil, and don't use modern two-cycle oil. Put oil in the drippers and make it look like they are in use, but don't actually drip, as you may overlubricate and just cause a lot of smoke and carbon buildup on the plugs, etc.

The problem with modern two-cycle oil is that it is formulated for high swept piston speeds and very high temperature burning, as in chain saws, and in too many cases it doesn't burn well in a relatively cold marine engine, and in turn it comes flying out the exhaust pipe and makes a big mess.

It should be noted the gasoline, up until about 1914 when so-called 'case headed' gasoline began to be made, was not unlike high test aviation fuel. It was very volatile, which explains why almost any carburetor would work. Many considered the 'new' gasoline as not much better than kerosene.

Another significant change that took place around 1908-1910 was the switch from pipe threaded intake, exhaust and cooling water cylinder connections to SAE style flanges. This was because so many costly cylinders were cracked trying to remove a rusted pipe connection. While SAE style flanges were first standardized for the automotive industry in 1912, unfortunately they never were in the small boat marine engine industry.

A related early change that was widely adopted was splitting the crank-case near the center line of the crankshaft so the flywheel that had rusted to the crankshaft didn't have to be removed to service the crankshaft bearings.

5. Essentially all the early marine engine makers used so-called mixer valves for the carburetion function. Most makers purchased engine trim such as mixers, carburetors, drip oilers, petcocks, pipe fittings, pumps, etc., from manufacturers who supplied the then very large steam engine industry. A few such as Palmer Bros, made their own mixing valve up until about 1907.

The Schebler Model D carburetor came on stream in 1901. This float feed carburetor was ideal for the small boat marine engine. Other popular carburetors of the period 1903 on, for small boat marine engines, were Krice, Kingston, and a whole series of knock-offs of the Schebler Model D. Most engine makers would supply a carburetor specified by the customer. Many owners tried (generally in vain) to get more speed by trying other carburetors; hence it makes it difficult for today's collector to know if the current carburetor is original to the engine. In my opinion if the carburetor is correct for the period it is correct, even if it may not be original.

With the development of reliable float feed carburetors, the shift from mixing valves was well underway by 1905. This was done to overcome the fuel leakage problem inherent in a worn mixing valve with gravity feed from the fuel tank which could be very dangerous in a boat. It is true however that quite often a balky two-cycle, three-port engine can be made to run well using a mixing valve or a check valve between the carburetor instead of just a carburetor. (See Fig. 1 for a typical marine check valve.) The reason being the three-port engine requires a tight crankcase and when the engine becomes worn it becomes hard to start. The check valve that the three-port engine was designed to eliminate restores, to a degree, the crankcase integrity and in effect, converts the three-port to a two-port engine. One of the basic reasons the watermen liked the two-port engine was it kept on running after years of wear. Thirty years was not unheard of, whereas the three-port demanded close tolerances to minimize crankcase pressure losses. The weekend yachtsmen seemed to prefer the three-port because it tended to operate at a slightly higher r.p.m., and in some cases was a smaller and lighter engine which did not stress the hull as much as the heavier two-port workboat engines.

The Schebler Model D and its contemporary kin worked well in the marine application because the need was for a relatively constant air/fuel flow and not a throttled flow as in an automobile. Cordwood saws with governors come to mind as applications where they also worked well. The Model D worked well with the two-port engine with the addition of a check valve. For a three-port engine in good condition the Model D or its contemporaries worked well without the check valve.

Watermen knew their engines seemed to work better on damp days than on dry days, so some lowered the carburetor into the lower portion of the bilge below the floor boards to pick up the moist air. I should add this had to be tempered with the depth of water accumulation in the bilge.

It might be noted that while many watermen used Model T Ford spark coils for ignition, essentially no one used Model T carburetors on marine engines. 'Cady' of Canastota, New York, did on the Model T Ford engines they converted for marine use in the 1920s, but they were a rare example. Dubrie used a bronze Holley, Ford carburetor.

6. The adjustment of the ignition systems on two-cycle two and three-port marine engines is different for so-called 'jump spark' and 'make/break' from the typical farm style hit/miss or automobile engine. One of the great advantages of the two-cycle marine engine is the ability to 'reverse on the spark.' A few single cylinder small boat four-cycle marine engines were made that were capable of direct reversing by shifting the exhaust valve and ignition timing, but they were the exceptions and not the typical four-cycle marine engine.

One of the least understood aspects of the marine ignition system is the fact that in those systems driven by an eccentric/strap off the crankshaft the engine in effect does not know which direction it is turning, therefore one can set the advance to essentially the normal operating advance and then rely on the on-off switch to reverse the engine. In the typical case the waterman would close the switch and 'stomp' on the flywheel spoke in the opposite direction he wanted the engine to turn and it would fire and go in the direction wanted. To reverse on the spark, he would cut the switch until the engine had almost stopped. Restoring the switch and the engine would generally reverse direction. This operation often raised bets among watermen as to how many times they could go one stroke in each direction. Depending on how finely tuned the engine, often simply pushing the flywheel with a boot would start the engine.

In the case of the Rotary timer type ignition systems, it was customary to set the timer at center range on top dead center. This then permitted one to set the spark to retard for either direction of rotation of the flywheel. As it was a common practice to rock the flywheel against a retarded spark (retarded for the running direction), this would cause the engine to fire and run in the opposite direction. One then advanced the spark in combination with the needle valve and throttle plate to determine the engine speed. One had to shift the timer to the opposite retard setting to start running in the opposite direction. One could reverse on the spark but one generally had to move the timer to the retard position at the same time as manipulating the on/off switch.

In effect the engine knows which direction it is turning and therefore, whether it be a miter gear driven rotary timer or a so-called 'swing arm' timer operated off a cam face on the crankshaft, one has to shift the timer to the running retarded position when reversing the engine on the spark.

It should be noted that for extended running with spark coils like the Model T Ford, many watermen used two sets of dry cells. Typically 6-7.5 volts in each set. One set wired to positive ground to the engine and one set negative. A three position switch to the coil(s) was arranged Plus-Off-Minus. In typical operation one set would be used for approximately one half hour and then the other set. This not only extended battery life but more importantly minimized point buildup on a coil vibrator. With Make/Break ignition on, the battery voltage would tend to be a little higher, perhaps 7.5-9 volts. While two sets of dry cells were used polarity reversal wasn't practiced.

7. Two-cycle engines flood easily and generally the reason for hard starting is not following a consistent procedure.

A. Maintain a reasonably rigid 40/1 mix of oil and fuel.

B. Prime a cold engine with the same mix as in the fuel tank. Don't wash down cylinder walls with raw fuel.

C. Set spark for normal cold start. Check for good spark.

D. Leave priming cup open and crank or rock engine until it fires one time. THIS IS MOST IMPORTANT.

E. If engine doesn't fire after a few tries, stop and open the drain on bottom of crankcase. Quite often oil and gasoline, even water, may pool in the bottom of the crankcase, and this can make it most difficult to start. Typically the engines were shipped with pipe plugs in the crankcase bottom and the boat builder would install drain pipes with valves brought out from under the engine so the boat operator could easily drain the crankcase of each cylinder. Being two-cycle each cylinder crankcase is independent from any other cylinder. If the crankcase is not flooded try one more priming cup full. Make sure you rotate flywheel so the downward motion of the piston will draw the prime into the engine. If this priming fails to fire, stop, and look again to any ignition problems.

F. If the engine starts but only runs a few strokes and then dies, it may be that new rings, bearings etc., have not been properly run in and the engine is too stiff to run. In the factory a new or majorly rebuilt engine would be belted up to a line shaft and rotated for hours until the engine had limbered up. One simple test is a well limbered up engine will rotate with only finger tip pressure when the compression is released. When a stiff engine starts as soon as the extra energy imparted by rotating the flywheel dies away, it cannot keep rotating and it stalls. Spinning the engine with another engine may get it up to a speed fast enough to keep running but that does not solve the basic problem. It needs to be limbered up!

G. If the engine is limber and it starts and runs a few strokes and then back fires or 'sneezes' through the crankcase, it can simply mean the needle valve setting is too lean or, more ominously, the crankcase is leaking through worn crankshaft bearings or leaky gaskets. Any play in the crankshaft when the flywheel is lifted is too much! Heavy water pump grease may help momentarily if the bearings are not too badly worn. In a three-port engine try adding a carburetor inlet check valve or mixing valve and see if that improves the operation. If it doesn't, it means a serious overhaul is probably necessary.

H. One common problem that is easily corrected is the so-called 'four-cycling.' The air fuel mixture is too rich. Close the needle valve slowly and the engine should immediately pick up speed and run two-cycle. Keep in mind the needle valve adjustment on a two-cycle engine is very precise when compared to a four-cycle engine. Its setting on damp days may be slightly different from dry days, so move it very carefully.

I. When trying to start a two-cycle engine where I don't know the correct needle valve setting I do the following: Close it. Prime engine. Get first firing through petcock. Close petcock and try to start the engine. It will probably run a few strokes. Open needle valve say one-half turn. Repeat priming sequence only this time the engine may run after a fashion. Quickly try adjusting the needle valve. If you are lucky you will soon determine if the needle valve is too open or closed. You may have to repeat the procedure a number of times to get the correct needle valve setting. Just remember, you must get that first firing every time you try to get the engine running, as it is too easy to flood it.

J. Marine engines run at shows typically get hot, and unlike hopper cooled farm engines where no water pump is involved, most marine engines have a water pump. Most are plunger pumps as they tend to handle trash better than gear pumps.

In a boat the cooling water was typically pumped from the bottom of the boat cold and through the water jacket and discharged either down the exhaust pipe or over side where the waterman could keep his eye on its flow. Some watermen painted the water jacket with red lead which changes color when it gets hot. The pump packing was typically flax soaked in wax. This of course doesn't work with hot water at a show. I find the best packing is the round Teflon packing that plumbers use. For example 7/32" for a 1/4" pump plunger/gland clearance.

Put a positive head on the water supply to the engine. I invert a drywall bucket and set one on top of it so the cooling water is above the engine cylinder. If the pump fails the water jacket will have some water circulation. Boiling water won't have any long term impact on the engine and shutting down the engine will allow it to cool slowly. Don't run cold water into a hot engine!

K. Don't hang old-time heavy cast iron mufflers on the cylinder. When installed in a boat great care was taken to insure the exhaust piping did not stress the cylinder. Often a short section of steam hose isolated the cylinder from the exhaust line. Jacket cooling water injected into the exhaust line cooled and quieted it. For shows a 30" section of 1" or 2" inch diameter copper pipe generally works well and as the engine isn't working under load, it makes an acceptable muffler. One caution that needs attention is some old time marine engines have so-called 'wet exhausts.' This means that the jacket cooling water is exhausted into the exhaust connection and it cannot be removed from the exhaust gas stream without serious modification of the engine. The exhaust from one of these engines is a wet black oily mess that won't gain the exhibitor new friends.

L. If the engine was salt water cooled it will crack if the cast iron water jacketed parts are allowed to dry out. It is almost impossible to stop the process once it starts. After years of exposure to salt water the cast iron water jacketed parts will have soaked up salt in the pores of the iron and it cannot be removed. Often when turning cast iron parts such as badly pitted flywheels, flange couplings etc., salt penetrations as deep as 3/16" are commonly encountered. Because of the salt, welding or brazing rarely lasts. The best solution is one of the epoxies. There is no significant water pressure in the water jacketed parts and I have found epoxy lasts for years. To keep the engines from drying out, the old-timers filled the water jackets with used motor oil or kerosene. Oil is messy and kerosene can permit the rusting to continue. For lack of a better solution I use automotive antifreeze with no water to keep the oxygen in the air or water away from the salt, whenever the engine is in storage.

In my opinion any salt water cooled engine that shows any cracks in its water jacketed parts is in serious trouble and it will probably get worse. Such an engine that might be worth $1500 un-cracked is now in the $150 class as it is so hard to find good replacement parts. Once the cracking starts all one can do is slow it down. Examine the water jacketed parts very thoroughly for any evidence of cracking or cracks covered up with paint.

M. A common error is for the novice restorer to insert a two-cycle piston with the baffle on the top next to the exhaust port instead of next to the intake port. While the engine may run, it generally is hard to start and it will run very rough. Often this condition can be seen through the exhaust port.

N. Do not put a shut off valve in the water jacket discharge line. The plunger pump acts on the water like a hydraulic jack and can break out any water jacketed parts.

O. The headless or dome head marine cylinder can trap a piston if it is shoved up far enough for the top ring to expand into any recess at the top of the bore or into a valve port on a four-cycle engine. If this happens, one is in deep trouble, and it can happen. I either cut a disk of wood and push it into the bore while I am fitting rings, etc., or if there is a pipe plug in the center of the head I place a length of  3/8" All-Thread' in the pipe plug and adjust the length to insure I cannot push the piston too far into the bore.

P. Two-cycle piston rings are pinned to keep them from being caught in the ports. Make sure no ring gap is in any port. Sometimes to do this two ring gaps may be adjacent. This is not important. What is important is, no ring gap is in any port.

Q. Two-cycle marine engines with small flywheels and no load don't as a general rule idle down like the typical heavy duty engines used by the water men, so don't be surprised if your three-port wants to jump all over the parking lot. Put a heavy base on it and place 6" square pieces of truck tire tread under the four corners if you are operating on a hard surface. I should add there seems to be an inexhaustible selection of tread along any well-traveled road and the price is a bargain.

R. As a general rule, I advise against splitting the crankcase if at all possible, because too often the replacement gaskets are too thick and the engine is in worse operating condition than before. Don't try to rebabbitt unless you have real experience doing it. Crankcase bearings in two-cycle engines are not the same as in hit/miss engines or saw mandrel bearings.