Atomic 4 overview

Atomic 4 overview for the “Pot ‘O’ Gold”

When we took delivery of the boat, we had no idea as to the condition of the engine. After determining that the engine would start, and the compression was ~110 on all four cylinders, we decided we would work with this engine and get to know it. I am NOT a mechanic, and the extent of my taking things apart had been bicycles as a teen, and I once tried to change the engine in an old Rambler, both cars, engines and parts went to the junkyard.

Although the motor ran during the first three trial years, (plenty of issues, read the deck logs on the web page) it had issues with fuel, ignition, exhaust, alternating, cooling, and ventilation. We also changed propellers. After a learning curve, each item was tackled individually, and a simple working solution was provided, that held up for the duration of the Great Circle Loop (over 6500 miles) motoring over 4000 of them in a year.


For the first two years the exhaust was a major headache. The “pipe within a pipe” system was heavy and the threaded ends corroded and were continually falling off. The final solution was to install a heavy rubber bunji cord to relieve the weight and vibration. The beauty of this system is that the water is completely seperate from the exhaust (and can therefore not be sucked back into the engine head) until the end of the riser and after the drop to the waterlift. The pipe itself is a heat exchanger that cools the exhaust without mixing.


The fuel in the boat was several years old when we took delivery, and smelled like varnish. After trying to burn it through the engine, it was eventually dumped out the tank cleaned and the carberator rebuilt. An additional fuel filter was added after the tank and this solved the fuel problems.


The year prior to our trip was the only time I ever had to get a tow for “Pot ‘O’ Gold”. After anchoring in a bay, the engine would not start. After an hour of troubleshooting with Don Moyers “non starting checklist”, I determined the problem was in the points. I was able to clean the points up a bit, and had a spare new distributor cap that I installed, and now everything appeared to be working as it should, but the engine would not go. We sailed home, received a tow into our slip, and as a last resort before calling a mechanic, I turned the distributor cap around, and presto, the engine started and ran. It was at this point I decided to convert to electronic ignition. For the difference in price, I purchased a whole new distributor with the electronic ignition already installed, then purchased new points and condensor and rebuilt the old distributor as a spare.


When the boat arrived, the alternator was not “alternating”, so rather than attempt to repair it (it was the original 33 amp model) I researched and purchased a new 75 am “marinized” Delco and installed it. It has worked flawlessly, although it was difficult to keep the belt tight so we went through several alternator belts until we found a solution. The original mount had to be adjusted as well.


The engine had an original bronze raw water pump when we received it. When I took it apart, there were very few parts inside, and it was pumping well. As long as grease was kept in the grease cup, and turned every time we went out, it worked great. After a few years, the temperature continued to rise, so further investigating was required and it was decided to add a thermostat (140), a new raw water pump, and clean the outlet of the exhaust. The thermostat housing studs broke when I tried to remove them, and it required drilling them out, and installing new, larger studs (larger on the bottom, same size on top to avoid drilling larger holes in the housing). When doing this, I realized that someone had worked on this before, and had drilled through the head into the engine. This is just for future reference for me, as there is a slight head gasket leak here that seals itself as soon as the engine warms up, so I have not worried about it. I have no desire to remove all the head bolts, I am sure every one will require drilling. I installed the thermostat, and it worked great for a few years. After about 500 miles on this trip, the engine overheated, and it appeared that the thermostat was sticking. When I tried to remove the housing, a stud broke and I had a machinist rebuild it for me, and I put it back together with no thermostat, I use a ball valve to adjust the temperature when necessary. For the most part, the engine runs around 130 – 140 with the ball valves (there are two) closed halfway. If I full throttle the engine, it goes up to 150 – 160. I have found no need to put a thermostat back in, and it is one less worry.

On the Trent Severn, we had an issue with seaweed getting into the fittings of the water intake and plugging it off, so I eventually installed a filter than can quickly be cleaned.

I purchased and installed a new raw water cooling pump from Moyer Marine, a new design from him that does not require me to turn the grease cap, it has sealed bearings, and an easy remove plate back (has four thumbscrews) for impeller replacement and inspection. When we were getting all the seaweed in the Trent, I was required to remove the back and use a mirror to inspect the pump, and when I put the backer plate on, the little (very thin) “O” ring did not stay in the groove, and the pump eventually leaked bad enough that I had to do something. I cut a rubber gasket out of some gasket material I had brought and put it on, which solved the issue completely. After discovering how sandy and full of material the inland rivers are, I purchased a new impeller and rebuild kit for the pump, which includes a new “O” ring, if I need to, I will install it by using a little grease to hold it in place.

Lastly, we gave the water cooling passages in the engine a thorough cleaning by pumping vinegar through the engine (clamping off the by pass hose so it all goes through the cooling passages) and leaving it circulate until hot, then letting it soak and doing again. After it came out clean(er) it was again heated, and pumped out through the exhaust, and after a bit leaving it soak then pumping out. So everything is clean, I will do this yearly, its not that hard and will keep the engine and exhaust clean inside.


During heavy weather in the Gulf of St. Lawrence, the boat can heel over more than our agreed 12 degrees when we are cruising. When this happens, I start the engine, unfurl the headsail a bit to stabilize, and head for safe ground. My first mate (and wife of 30+ years) heads below. When the wind was blowing the right way, she would get fumes from the engine that would further her nausea, and she requested I find a solution. I was going to install another and larger bilge blower when I came across a solution from Indigo Electronics that was both inexpensive, easy, and seemed to fit the bill. Their crankcase ventilation system kit was designed to take these fumes, and inject them back into the engine through a PVC valve, and out the exhaust, and the cost was less than $100. I ordered one, installed it, and cleaned the carb while it was off. She absolutely loves the system, we have had no trace of any fumes, and it truly was easy to install.


Our boat came with a 2 blade folding propeller. It was a great prop for the Northumberland Strait, where there are lobster traps everywhere I sail, it seems. With our full keel, we never did hook a trap. Backing up was a challenge, however. It seemed I never had any control over where the boat was going to go. The three blade bronze propeller from Indigo was our choice to switch to, as they claimed better control in reverse, and would increase the RPM of the engine so it would run a little faster, and more efficient.

I did not notice any improvement in reverse until after I had several hundred hours of motoring in and out of harbors and tight boat slips that required increased control, especially in Montreal. I think it was probably the helmsman getting more experienced at how to deal with the side slippage of the full keel in reverse than it was due to the prop. The engine RPM’s do seem to be a little higher, and the engine is running great. I feel a need to avoid lobster traps now, however.


This amazing little engine has done an incredible job. It is close to 40 years old (1969 vintage) and has never been rebuilt (and never will be, if it quits, I will junk it). At cruising speed (~ 5.5 knots) it burns 3/4 gal per hour. Full throttle about a gallon. Specs say it develops 30 hp, it pushes our 10,500 lb boat through high waves in a gale, and for the most part gets us home (only once failed to, due to me putting the distributor cap on backwards).

If I had to do it over again, I would not choose a different motor.

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