Atomic 4 Gasoline engine

[wannacat]

We've had an Atomic 4 since 1977 in our C&C. Runs great and simple to work on as mentioned. My only suggestion would be to get the"electronic ignition conversion kit" from Moyer Marine. They will discuss and help you with the install, it's an easy task! As mentioned, proper ventilation is key to safety. I would be more worried about any propane appliances onboard than the gas engine!

[S/V Alchemy]

Originally Posted by Christiansailin

I'm considering the purchase of a 30ft Morgan which has an Atomic 4 gas-burner. My presumption is this will not be as efficient as a diesel but I've never really given much thought to it either until now. Anyone currently using ot has used in this motor?

We're on the lake/river in TN so auxiliary power will be utilized. We do have plans to transit to the gulf but will likely be 2018 but believe fuel cost would be higher with gas burner.

Thoughts?

Thanks

They are reliable, simple for the owner to service and maintain, and, of course, the fuel is available everywhere. They have less range, however, than for a comparably sized amount of diesel fuel, but the cost of repowering in diesel would likely exceed the cost of what you paid for the boat, and you'd never get it back. So buy some jerrycans and a decent funnel and maybe replace the gas tank with something larger. A fuel-water separator is also a nice add-on, as is a fuel line shut-off outside of the engine compartment.

I've rebuilt two of these and one of them is in the boat I sold last fall. It started very readily after two years on the hard and after I swapped out the gas and charged the batteries. There is extensive online resources, tips and tricks and a still-large A4 "community" keeping them going, as a low-compression gas inboard has many advantages over a diesel for "head to wind" or "leaving dock" purposes, and less so for "24 hours of motoring" purposes. Be aware that the fuel consumption vs. thrust curve is quite steep; going five knots is "cruise" at 3/4 of a gallon per hours, but six knots will double that. Save WOT for clawing offshore or getting through a sea wall opening in a blow.

Hope this helps.

[sailortype]

"Your presumption should be that you would be buying a ticking time bomb."
yup, total 'inflammatory' nonsense. I had one for 20 years on my old old boat and pleased to have one on my new old boat. These engines were installed in 40,000 boats... how many blew up? they are still operating in an estimated 20,000 boats.
As mentioned above, one cannot be sloppy or stupid and one has to attend to good installation, good maintenance, ignition protected equipment and proper use of blower.
But they are quiet, unsmelly, easy to work on by reasonably handy owners, and go forever. Might use maybe twice as much fuel but, depending on use, you have to save a LOT of fuel to justify $4,000-6,000 for a diesel repower on economics alone.

[Mike OReilly]

My previous boat had an A4. Good, solid engines. Simple to maintain, and good support in the community for them. Certainly not as efficient as diesel, but fine for someone cruising locally/seasonally. Not the best for full timer cruisers covering longer distances.

The the dangers of gasoline are real — much like many things on a cruising boat. Propane is a greater risk than gasoline on a boat, yet most cruisers wouldn’t be parted with their gas stoves. As with all things, use it wisely and you’ll be just fine. In this case make sure the boat has good engine ventilation and effective blowers. There are thousands of A4s still in use. Certainly don’t here about many blowing up.

[sailortype]

read one anecdote about one Atomic owner arguing with another boat owner who had a diesel about the dangers of a gasoline engine. The guy with the diesel had a couple of jerry cans of gasoline in the engine room for his dink. Go figure.
And so true about the propane... MOST installations are just not safe.

[gjordan]

Early A-4s had mechanical fuel pumps, so if the engine dies from some cause like a stuck float, the fuel pressure dropped quickly. Then they went to electric fuel pumps that were wired to the ignition system and if the engine died, fuel pressure stayed up and if there was a leak it kept leaking. The latest upgrade (that I know about) is that the fuel pump electrical hook up runs through an oil pressure cut-off switch so that again the fuel pressure drops quickly if the engine dies. Modern fume detectors and proper use of the bilge blower make them a safer option than they used to be. You are much more likely to lose your boat from a hose clamp rusting through than you are from an explosion. Most of us would rather have a diesel (including myself) but the budget makes us compromise and if well maintained the A-4 will do the job. Just another opinion. _____Grant.

[30yearslater]

+1 for the A4. Can the mechanical fuel pump and buy the electric. The diaphragm on the mechanical pump was the number 1 reason for problems. Rebuild the carb. Insure the coil is a resistor coil or there is a resistor mounted. Other than the fuel economy issue the thing doesn't gag you with fumes like a diesel. How many diesels ever get run up to speed? Great way to soot them up running at harbor speeds. Gas doesn't care what RPM it runs. Most boats built have gas engines in them and there isn't a plethora of explosions. Economy is the only plus to a diesel but then it's in a sailboat isn't it?

[Sorcery]

My boat is vintage 1977 with an atomic 4. I put in electronic ignition and a new coil. Do regular service( oil and plugs) very reliable, smooth and quiet compared to my friends diesel. Lots of atomic 4's in my club. No problems with any of them. Uses more fuel than a diesel. If you like the boat enough there is a Kubota diesel replacemt that's not very expensive but the Atomic 4 is a great motor.

[sailortype]

good point Grant... an electric fuel pump without the oil pressure shut-off can definitely create a dangerous situation in a real hurry.
Back to good installation and maintenance.
The PO on my boat had installed two small lawn mower type plastic in-line fuel filters with no hose barbs... back to no stupidity.

[RKO]

This past winter, I motored my Columbia 8.7 from Lake Barkley to Louisville KY. It was a 350 mile trip, practically all against the Ohio River current. We used about 1.3 to 1.5 gallons per hour at cruising speed.
The motor ran like a charm, by the way, BUT I had it rebuilt before the trip. It damn well better have run well!

People who say things like "ticking time bomb" are usually what I call "internet sailors." At least as it relates to the A4. Usually they only parrot what they have heard from other internet sailors on forums.
This forum is largely different though. Real sailors, much more so than me, hang out here.

[Brewgyver]

I've had my A4-powered Catalina 30 for a few years now. Had a couple of problems that were cooling-related, wound up replacing the manifold ($150 score on eBay) and constructing a new hot section/elbow for the exhaust. Zero problems since.

When I was shopping, I had looked at several diesel-powered boats in the same price range, and started off more or less ruling out boats with A4s. I noticed a boat in really great shape (for a '78) sitting on CL for months, and it was in my own harbor. Before I bought the boat, I spent a fair amount of time searching the web for A4 explosions. Couldn't find any. Lots of boats burned to the water line from carelessness while refueling, but none related to normal operation.

Of course I have a blower, and religiously run it for several minutes before starting the A4. But before even before starting the blower, I check the engine compartment (under the port settee and galley cabinet) for fuel odor. The raw water through-hull is right next to engine, and I keep it closed when not running, so I HAVE TO get my nose into the space to open it every time.

[Southcoasting]

Originally Posted by Christiansailin

I'm considering the purchase of a 30ft Morgan which has an Atomic 4 gas-burner. My presumption is this will not be as efficient as a diesel but I've never really given much thought to it either until now. Anyone currently using ot has used in this motor?

We're on the lake/river in TN so auxiliary power will be utilized. We do have plans to transit to the gulf but will likely be 2018 but believe fuel cost would be higher with gas burner.

Thoughts?

Thanks

Get the boat if all else is okay...An A4 is never a reason to not buy a boat...In fact, it is a great reason to buy a boat at a discount!

My previous boat had one and the new one does too..I bought a used one to rebuild/paint etc to replace mine...no reason, just good to have a nice newer engine...gas consumption on these is between .75 to 1 gal per hour...depending on rpms you run it at, boat size/weight and prop...

I mainly sail...Seldom use engine...on sailboats, engines are called "auxiliary" for a reason...

Most people's boat's catch fire because of bad electrical...so don't worry so much about it blowing up like some try to claim...how many gas cars have you seen blow up because they have gas engines? Can't believe people still bring this up as if it's real...Fake news...

Buy the boat and focus on electrical inspection so that is does not blow up from bad wiring techniques...and join the Moyer forum...those guys are awesome and always lend tons of info and help!

[sailortype]

it is likely clear that most who have the atomics love their engines... and for several good reasons.
They do not call us Afourians for nothing : )

[bsurvey]

universal makes a drop in diesel that will fit the motor mounts and coupling. its a Kubota block. very reliable and easy to get parts for

[Terra Nova]

When I had written "ticking time bomb" I truly was not referring to the dangers of gasoline fires on boats, the dangers of which should be obvious (but apparently aren't) to even the least experienced sailors here. Rather than a literal explosion, I was referring to the fact that most of these engines are virtual antiques, many of which have been repaired by amateurs, with some of the repairs I've seen to include patching oil and water leaks with Marine Tex!

Some here have proudly quoted Wiki's statement that 20,000, of the 40,000 engines made, are still in service. That's 20,000 failures, or 50%! That's the ticking time bomb.