Atomic Four .......Could You?

[Group9]

Originally Posted by rebel heart

My old A4 really helped my sailing skills develop.

Laughing because I was thinking the same thing. You will get to know Moyer Marine people well if you have one, that's for sure.

If Moyer went out of business, I think the Atomic 4 would be gone in five years.

[ElGatoGordo]

I had one for years in my Irwin. It was flawless, relatively quiet, and fuel was easy to get. And it was NOT well maintained by PO, was raw salt water cooled, and had zero modern updates. If you already know how to work on an old car, this engine will be very familiar.

As to parts, yes Moyer has them ALL. BUT, and I can already hear the cries...NAPA does too! The vast majority of parts you'd need fast can be found at any auto parts store.

[Sailmonkey]

Originally Posted by ElGatoGordo

As to parts, yes Moyer has them ALL. BUT, and I can already hear the cries...NAPA does too! The vast majority of parts you'd need fast can be found at any auto parts store.

The only thing I can add to this is you can get virtually all of the parts from napa, etc.... But you'll need to find the guy behind the counter who is willing to look, rather than the guy who gives up when universal, or Atomic don't appear in his computer.

[Blue Agave]

Originally Posted by Blue Crab

Am boat shopping. A boat I really like has an AF. I'd prefer a diesel but this is a v-e-r-y clean setup with access. Not what you think of with an inboard.
I like clean. I can maintain clean. And the price is fine. I've been around many. I think I could live with it as a liveaboard cruiser.

Thoughts beyond the explosive possibility? I doubt heading to the South Seas.

I know people always bring up the gasoline explosion thing when atomic 4 is mentioned........but the real issue here is fuel availability. In a lot of the places that ive visited that were off the beaten path they had diesel and most had gasoline of some sort. I can run the diesel through my polisher until its clean but there isn't much you can do for low quality gasoline and it doesn't store well. beyond that if you like this boat and don't plan on going places where good quality gasoline is a problem Id say jump on it.

[Dockhead]

Originally Posted by Boatguy30

I wouldn't unless a fresh water boat. I did a partial rebuild on a salt water A4 2 years ago for a customer and was shocked at the cost of parts. You're far better off finding a boat someone has paid to repower in the last 10 years with diesel. This is pretty much the sage advice, but is totally accurate.

It's a question of money.

Of course if he finds a boat with a fresh Nanni diesel which is $2000 more than the same boat with a tired A4, then of course he should take the diesel.

But I don't think that's what he was asking -- I think he meant that if he finds a perfect boat but it has an A4 -- is that a reason by itself to reject it? I think the answer is no. If the price is right, of course.

[Dockhead]

Originally Posted by Liam Wald

Atomic 4's are great little engines. Easy to work on and they are very smooth running. Like someone else said, there are probably a million boats out there with gas engines that simply fail to explode as predicted.
The only down side is that Atomic 4's burn a gallon or more of fuel per hour so you motoring range is limited.

A4's are ancient technology -- flathead engines, updraft carbs, low, low compression ratio -- 6:1 or something, I think, and a redline of 3500 or something. Basically a pre-war antique.

This all amounts to mechanical simplicity, low stress, low heat, low noise, and a very long life -- all very good things on a boat.

The downside of course is efficiency, where a low-compression petrol engine really sucks. So this would not be a good choice for someone who planned on motoring for significant distances.


As to safety -- question of risks and precautions. It's a slight inconvenience, but if you blow out the bilges religiously and don't spill gas in the boat, religiously change your fuel hoses and double clip them, etc., etc., etc. -- I think the risks are very small.

[S/V Alchemy]

Originally Posted by Blue Crab

Good stuff. I can start over looking at boats I once passed over. Thanks, guys. I wouldn't mind the reduced noise at all.

I rebuilt mine 1973 model in 2005 for about $1,200. Starts first time, every time. Maintenance is a breeze, and I neither took shop nor own a car, so it can't be that difficult.

You may opt for post-market fixes like electronic ignition/fuel pump and a PCV kit. You may also opt for that yellow manual that gives you the correct head bolt torquing order (and foot-pounds of torque) and you may choose to do a tune up every two or three years with the $18 Sierra kit or the $44 coil. All parts are still easily obtainable and are generally cheap. Lots of people have bought an old block or two to rehab or scavenge for parts, but I understand you can even buy a new freshly cast Atomic 4 block from Don Moyer, the American who's made the Atomic 4 the core of his business.

Really, however, it's a reliable little engine that is perfect if you don't wish to motor 100 miles a day. Unlike diesel, the low-compression A4 doesn't care if it's switched on, run for five minutes and switched off several times a day. This alone is distinct and useful for the "head to wind, main up, engine off" sort of sailor most of us are. I hesitate to run my other boat's diesel for less than one hour until it's fully warmed up all the way through. Atomic 4s don't care so much.

About the only downside is the range of a gas engine is clearly inferior to the same load of diesel. On the other hand, I have trouble using two 10 gallon tanks of gas per year...because it's a sailboat.

[S/V Alchemy]

Originally Posted by Liam Wald

The only down side is that Atomic 4's burn a gallon or more of fuel per hour so you motoring range is limited.

I have a direct drive A4 in a 9,000 lb. Viking 33 sailboat. I use the hotter RJ12C plugs gapped to .040 and no other special enhancements (original mechanical fuel pump and points and condenser ignition).

At 5.4 knots (cruise speed in flat water) with a two-blade Gori folder (11.5 x 8), I burn exactly .73 gallons/hour. While your mileage may vary, naturally and not figuratively, I have found that it is getting that last knot of speed out of an A4 that is completely not wroth the gas or the reduction in range. At 30 feet LOA, you can get the same fuel burn at 5.1 knots or so, up and down the scale. Basically, if you can get over 6 knots at WOT, drop that last knot (more or less half-throttle) and you'll get far less noise, by-blow, and vibration. Save WOT for sudden stops or medical emergencies.

If the wind is light or foofy, we will motorsail and I can get that 5.4-5.6 knot SOG with the engine at one-third throttle, which without the sail would give about 4.1 knots, which lowers the burn to 0.5-0.6 gal/hr.

About the only useful instrument I would bother installing is a tachometer...as long as the temp is good for salt (145F) or fresh (175-180F) and the pressure starts at 45-50 PSI and drops to 25 when the oil's hot, you are pretty well good to run it all summer. Also, be aware that the direct drive version has a lower HP output than the geared: it's not "30" but more like 17 HP at the shaft. This doesn't have a huge effect one way or another. I wouldn't try it in a boat more than 35 feet or 12,000 lbs. displacement, however, at which point a diesel makes more sense from just an output basis.

[sailpower]

What about potential problems with the ethonal fuel blends here in the states including any possible tank/hose issues?

[um saudade]

If the A-4 is in good enough shape I would spend the money for a heat exchanger system. Long, long life and way better performance at 180 degrees, not to mention that so many of the typical maint issues go away when this engine runs at a decent temp.

Geared properly and not run at WOT, the A-4 will run on less than a half-gallon per hour when the carburetor is tweaked properly and the engine is at a normal running temperature.

Gas can be an issue but the gas in the states (alcohol or no) is the worst gas you can get for longevity. With the clean burning additives (butane being a key ingredient) the gas in the US will go flat pretty quickly, smell bad and run poorly. The gas in most other countries, including third world countries (I am not at all sure about Europe here) will have much longer “pot” life.

For engines that sit for long periods of time without running or go through a very small amount of fuel compared to the size of the tank, use avgas. The aviation fuel will last and last without going bad in the tank.

If you use regular US gasoline, keep a small amount in the tank as opposed to keeping it full. Condensation will not be a big issue as many claim and the fuel will be used up more often. If going a long way, then carry extra gas in a can that can be added as needed. Use a little Marvel Mystery oil and the valves will like you. A lead substitute is a good idea.

Electric fuel pumps work better than the mechanical ones, run a big filter that will also separate out the water and install some inline filters to get the stuff before it gets to the pump. If you don’t run it for a while, drain the carburetor and if you can, find a way to empty the muffler so the exhaust does not breathe in salt water fumes from the water in the muffler. An exhaust valve open to the muffler can easily stick in these engines.

Moyer is expensive for what you get and no, Napa does not have all the parts but many of the common things. Most typical alternators will mount on this engine and the starter is old school Delco. Only big starter issue is the light tension springs that hold down the brushes will rust away and the starter will not spin. A couple of dollar fix done (or checked) every 5 years or so.

Change the oil every 50 hours and this little engine will go a long time.

[Blue Crab]

Originally Posted by um saudade

If the A-4 is in good enough shape I would spend the money for a heat exchanger system. Long, long life and way better performance at 180 degrees, not to mention that so many of the typical maint issues go away when this engine runs at a decent temp.

Geared properly and not run at WOT, the A-4 will run on less than a half-gallon per hour when the carburetor is tweaked properly and the engine is at a normal running temperature.

Gas can be an issue but the gas in the states (alcohol or no) is the worst gas you can get for longevity. With the clean burning additives (butane being a key ingredient) the gas in the US will go flat pretty quickly, smell bad and run poorly. The gas in most other countries, including third world countries (I am not at all sure about Europe here) will have much longer “pot” life.

For engines that sit for long periods of time without running or go through a very small amount of fuel compared to the size of the tank, use avgas. The aviation fuel will last and last without going bad in the tank.

If you use regular US gasoline, keep a small amount in the tank as opposed to keeping it full. Condensation will not be a big issue as many claim and the fuel will be used up more often. If going a long way, then carry extra gas in a can that can be added as needed. Use a little Marvel Mystery oil and the valves will like you. A lead substitute is a good idea.

Electric fuel pumps work better than the mechanical ones, run a big filter that will also separate out the water and install some inline filters to get the stuff before it gets to the pump. If you don’t run it for a while, drain the carburetor and if you can, find a way to empty the muffler so the exhaust does not breathe in salt water fumes from the water in the muffler. An exhaust valve open to the muffler can easily stick in these engines.

Moyer is expensive for what you get and no, Napa does not have all the parts but many of the common things. Most typical alternators will mount on this engine and the starter is old school Delco. Only big starter issue is the light tension springs that hold down the brushes will rust away and the starter will not spin. A couple of dollar fix done (or checked) every 5 years or so.

Change the oil every 50 hours and this little engine will go a long time.

Super post. Thanks.

[sailpower]

Sounds like you have addressed any conflicts with the ethanol blended gas and the A4.

What about gas tank and hose issues? I have heard that ethanol can damage some kinds of tanks and some hoses. Any thoughts there?

[Bold Rascal]

The A4 is an extremely reliable engine and tolerates a lot of abuse, Guess that's why there are still so many pushing sailboats around.

Fresh water cooling is definitely a bonus, but regardless of whether its raw water or fresh water cooled, typical operating temps are in the 160-180deg range. If it runs warmer than that most likely there is a bad water pump, impeller or thermostat or interior build up that can be flushed out.

A simple compression test is to remove the spark plug and try to hold your thumb down on the spark plug hole while turning the engine over. If it displaces your thumb you have good compression.

If you have spark, good fuel and compression, the lil beast will run.
It is gasoline so you should always take the extra care.

Otherwise it's a great engine and spare parts are readily available from Moyer marine. They have an excellent and very active forum there as well.

You can also find a very good check list for surveying A4's from the moyer site that should prove very helpful to you.

Mines over 40 years old now, running great.

Just one more item to note, do not continue to crank over a hard to start engine with the raw water intake valve open. it could back flood the cylinders. Get the engine running first and then open the water intake.

[Bold Rascal]

Originally Posted by sailpower

Sounds like you have addressed any conflicts with the ethanol blended gas and the A4.

What about gas tank and hose issues? I have heard that ethanol can damage some kinds of tanks and some hoses. Any thoughts there?

Ethanol is definitely a problem for fiberglass fuel tanks. Regarding hoses, I would for sure spend the extra $5.00 and replace them with ethanol rated hoses.

Moyer might be a tad more expensive (on some item's) but they are top's in spare parts and nobody has better parts service and helpful "free" experience.

[nimblemotors]

Originally Posted by Guy

Diesel fuel stinks.

+10 and they smoke, vibrate, really loud, very very freekin heavy!
I just don't get it, the fascination with diesels on sailboats.

Direct injected two strokes are the best invention since the hybrid,
all the upsides of two strokes, no downsides.

Oh yes, I should mention, this is 2013, it is not 1965 anymore, or 1985, or even 1995,
there have been advances in engine technology.