Atomic 4 engine pros and cons

Stu Jackson · Dec 19, 2011

Hi, Recess. As a "regular" here, I'm surprised you haven't seen this question asked and answered. Many times.

Mileage is half.

Gasoline requires careful vigilance. Outboards, at least older ones, need premix of fuel and 2 cycle oil, the A4 takes straight gas.

Gas is available everywhere, diesel too for the most part.

Moyer Marine has everything you need to keep one going, including updated electronic ignition systems. And complete engine blocks.

Vapors? If you have any leaks with either fuel one hasn't done proper maintenance. BOTH fuels stink and have no place on a properly maintained boat.

Gas? BOOM. Diesel? Not so much.

Happy hunting.

Oh, one other thing: resale. Gas less, so the boat will be less expensive than a comparable diesel engine, but the same for when you go to sell.

tommays · Dec 19, 2011

As a happy A4 owwner with and all new fuel system from the tank to the motor all it takes is ONE eye dropper of fuel to stink up the boat

The big issue is a Fresh Water Cooled Motor in saltwater as the RWC ones are really tired

Rick D · Dec 19, 2011

A4

I have owned two. Actually, one was marinized by someone else, but the same engine. The first one was in a Columbia 28. I had problems until I put in a water-separator filter and rebuilt the carb. After that, no problems at all. I loved the smoothness and quietness of the engine. It was the sweetest running thing. Best engine from that standpoint I ever owned. It was at least twice as thirsty as my diesels. Basically, that just means carrying more fuel and/or sailing more. The other one was in a launch. It had a different carburetor that the other and it was troublesome as was corrosion and sludge in the valve area which caused some broken valve springs. That was caused by too infrequent usage and running too cold (no thermostat and over powered for the launch). So, I wouldn't say it's a deal breaker at all. Remember that these were the marine standard not many years ago and traveled world-wide.

CalebD · Dec 19, 2011

There are an estimated 20,000 Atomic 4 engines still installed and running in various sailboats. The last A4's that Universal made are from the early 1980's.
Mine is from 1967 and is still running nicely thank you.
One of the best things about an Atomic 4 is that it is an extremely simple engine and therefore quite easy to do most (if not all) of the work required yourself. There is great support for these engines from Moyer Marine.

Boats powered with the Atomic 4 are generally a few $$$$ cheaper then boats equipped with a diesel as Stu suggests.

BobM · Dec 19, 2011

Funny thing is that most power boats under 40 feet are gas and they often have hundreds of gallons of the stuff aboard. However, sailboat owners seem far more freaked out about having twenty gallons aboard. My 18 foot powerboat has a 25 gallon tank and I wouldn't think twice about it.

The biggest differences, in my opinion, are range and reliability. That can be mitigated by planning and really is driven by what you plan for the boat. My boat can (and has) motor for over twenty hours on a tank (Yanmar 2QM15 burns about a quart an hour). Which was great when I was on a three day trip. However, we stopped every night and could easily have filled up, if necessary. The bigger problem is fuel stability. The last time I tanked up was bringing the boat up on the east side of the Cape Cod Canal...four years ago. I still have a quarter of a tank, because all I have done is day sail.

In any case...with two aboard I will fill the 12 gallon holding tank faster than I can empty the fuel tank.

JonnyQuest · Dec 19, 2011

Having a cheap old Atomic 4 on my boat has been quite a confidence builder for me. Not knowing anything about engines, I have gotten to a point where I can troubleshoot and solve every problem the A-4 throws at me--given time and patience. I had originally thought I woudl need to call an expert" when it came to the engine, however haven't needed to yet!

They are simple engines and the support at Moyer Marine and their user forum is invaluable.

Not sure if I would have tinkered and learned so much so quickly if I had started with a diesel engine.

Stu Jackson · Dec 19, 2011

JonnyQuest said:
Not sure if I would have tinkered and learned so much so quickly if I had started with a diesel engine.

I'm sure you would have. Most of us have, 'cuz when you buy a boat, that's what you do unless you "outsource" all the work. And those guys don't frequent this forum or others for that matter.

Question for the A4 gas engine guys: any problems with fuel storage now that "ethanol is your friend?"

philwsailz · Dec 19, 2011

Stu Jackson said:
I'm sure you would have. Most of us have, 'cuz when you buy a boat, that's what you do unless you "outsource" all the work. And those guys don't frequent this forum or others for that matter.

Question for the A4 gas engine guys: any problems with fuel storage now that "ethanol is your friend?"

Sta-bil is your friend...

I should take the time to clarify, that while I am an A4 owner, I have not run the motor for any length of time, much less in the water. I fully intend to be diligent in selection of fuels, as I will be carrying on and have access to advertised ethanol-free fuels.

To be safe, and as a result of my efforts at keeping fuel systems clean in my vintage outboard motors, (all old OMC stuff) I will be replacing all rubber fuel lines with new alcohol-resistant line and I will be installing fuel filtering to catch the inevitable solids that either fall our or are losened by the accidental introduction of ethanol.

I will keep you posted.

woodster · Dec 19, 2011

phil do you have a Yellow jacket runabout by any chance...not trying to hijack this thread...this question is a knee jerk action.....

thanks...

woody

JonnyQuest · Dec 19, 2011

I swore off ethanol gas (or, Just Say No)

Just like my lawnmower at home, it will destabilize (de-phase?) fairly quickly, considering how little gas I use to putt out of the harbor and back in again.

At first I used Sea-Foam, and I expect it helped. But I've found a couple of stations nearby that sell no-eth gas, and find that I get better gas mileage in my car when I use it. So I avoid the ethanol blended fuels for my boat, lawnmower, and car as well now.

I know! I'm such a rebel I can't help myself!

philwsailz · Dec 19, 2011

woodster said:
phil do you have a Yellow jacket runabout by any chance...not trying to hijack this thread...this question is a knee jerk action.....

thanks...

woody

Not anymore. I had a little Yellowjacket outboard utility but sold it many years ago. Grandmother-in-law still owns a runabout... My wood boats are Liberty Boatworks/Bellcraft, North American, and Burchcraft at the moment. The North American and the Burchcraft are for sale, btw...

tommays · Dec 19, 2011

Other than possible issues with rubber parts the older motors have LESS E-10 problems as the the carb jets are GIANT compared to new motors and much less prone to getting stopped up with small stuff

FWIW it took 9 years for my 19' 36 gallon tank powerboat to build up enough water in the TANK to ever even have anything reach the separator and when i sold it last year it had stabilized E10 fuel that was 18 months old and it did the sea trial without any issues

Of my chain saw ,weed wacker ,blower ,snowblower riding mower the only motor with any ill effects is the 4 year old push mower which just needs a carb clean-out

CalebD · Dec 19, 2011

Phase separation.

Stu Jackson said:
Question for the A4 gas engine guys: any problems with fuel storage now that "ethanol is your friend?"

Stu,
I think that this photo should answer your question. This was the last gallon or so of what I manually pumped out of our 20 gal. fuel tank this spring.
To be fair, we have owned the boat for 8 years and this year was the first time I tried to clean up the old fuel that has been in our tank for lord knows how long.
And BTW gasoline is my friend, ethanol not at all. If I could get alcohol free fuel I would use it even at twice the price. Non ethanol gasoline does not phase separate and turn into the crap shown in my picture. Ethanol is a menace and a disgrace.

Do any of you diesel guys have pictures of the green slime that diesel turns into when water and bacteria get going in the tank?

RobertLangdirect · Dec 20, 2011

I would be interested to see what refinery make e-free gas and how they ship it. I think that unless there is an easy way to test gas to ensure it is e-free, given that 99 percent of the gas made is now blended, I suspect that a lot of so called e-free probably isn't.

RobertLangdirect · Dec 20, 2011

CalebD said:
... This was the last gallon or so of what I manually pumped out of our 20 gal. fuel tank this spring.

To be fair, we have owned the boat for 8 years and this year was the first time I tried to clean up the old fuel that has been in our tank for lord knows how long . . . .

. . . Non ethanol gasoline does not phase separate and turn into the crap shown in my picture.

CalebD --

Wow. That looks a lot better than the crap I pulled out of GOOD TRADE, my 1978 P-31 that sat on the hard for five or more years after she was put away wet and cold by her past owner after a hurricane. I pulled crap, pushed gallons of carb cleaner and "dry gas," and changed filters weekly through a summer, as each outing washed more crap off the sides and bottom of the tank.

But eventually, it came clean.

So, is your fuel pickup really that high in your tank? It seems that you should have pumped out the crap off the bottom FIRST.

Also, thinking about a science fair experiment, you said that e-free gas won't phase separate and turn into the crap shown in your picture. Is there an industry citation that you can point to? From my own experience, e-free or not, gas will loose is most volitile products to evaporation and eventually turn to varnish.

I am not saying that ethonol is great for our boats. However, it is a great solvent. I think it actually helps to keep the tank clean. In your photo, it certainly suspended all sorts of crap. Would e-free gas had removed that or let it sit in your tank?

Rick Webb · Dec 20, 2011

Blended Gas

The eathonal is not added untill the truck is filled at the distribution point. They can not run it through the pipelines or store it which is one of the reasons it adds to the cost at the pump.

Atomic 4 engine pros and cons

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