Atomic 4 Gasoline engine

[sailortype]

interesting points re the A4 bearings Jim. Probably for sure these engines were never meant for long term long distance cruising. And the price difference alone for long distance cruising makes repowering a lot of sense.
But again, point well taken... although 'gas fumes are a major cause of boat explosions'... boats with A4's are not regularly blowing up despite all the horrible maintenance. Do we know one that blew up..?
A well installed well maintained gas A4 is 'safe'. To be sure, gasoline is not SAFE, nor is boating for that matter. All sorts of varied accidents and fatalities.
Nor is hockey... I was injured three times this year, but I am not going to switch to diesel hockey.

@Boatpoker... "engine compartments with grills at the companionway venting into accommodation spaces,"
Most of your examples are more than obvious dangers, but I do not get this one. In most boats, the engine compartment and living areas are just one big happy space via the bilge. Engine compartments are rarely sealed off from the cabin and gas fumes if any, being heavier than air, end up in the bilge and therefore in the cabin area. What is the issue here..?

[hamburking]

I had an A4 in a 1972 C&C27 and a 1971 Paceship 29.

The A4 is a reliable, solid, safe engine. Easy to work on. Parts and expertise easy to come by.

But it is thirsty for gasoline. This is a big deal. Although it will vary depending on the particular boat and installation, I would say the A4 uses 4 to 5 times the fuel of a diesel in the same boat.

I replaced my 1972 C&C27mk2 (A4) with and 1982 C&C27mk4 equipped with a yanmar 2gm. I usually ran at only 1800 rpm, and that yanmar sipped less than 1 litre per hour at 5 knots. With a 75 litre tank, that gave a range of over 400 miles. Our older C&C (with A4) had a range of around 100 miles (or less).

This is kind of a big deal!

For me, it the difference between filling the fuel tank after every weekend, or after every season!

When buying an older sailboat, its often said you are buying the engine, and it comes wrapped in a sailboat.

[Adelie]

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

Gas will provide about 10hp/gal/hr vs 18hp/gal/hr for diesel. So diesel fuel mileage is about 1.8 time that of gas when operating at the same speeds.

Gas is not a safe as diesel, but it is not dangerous per se.

Gas engines are a lot quieter than diesels.

Atomic 4s are common throughout the US and well supported by Moyer and one other dealer if I recall.

Atomic4's are a bit more tolerance of grungy fuel.

Gas does not have problems with things growing in it.

The absolute and relative price of marine fuels varies over time. Currently Diesel is about $2.40 and gas is $3.20 on the Tennessee. Over the long term I would expect that prices average out to be even.

Similar horsepower diesels (29-30hp Betamarine & Yanmar) are slightly lighter (310lb) than an Atomic4 (310-330lb depending on model).

You may not use a galvanized tank with diesel.

A $2k price difference will buy you a lot of fuel to make up for the difference in mileage.

If I was going to stay in the US or the Caribbean I wouldn't hesitate to keep an Atomic4 in decent condition. Europe probably wouldn't be bad. Elsewhere I would be hesitant.

[Hudson Force]

Originally Posted by Terra Nova

....................
................ 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! ............... That's the ticking time bomb.

Oh, the horror,- amateurs using Marine-Tex! I just read through this thread and had a great laugh with this. It's true. Marine-Tex has been used for amateur repairs! About forty years ago I gave an extra two years of functional "life" to my raw water cooled Atomic Four with corrosion leaks in my salt water cooling jacket.

Being able to keep an engine running for an extra two years with a repair costing less than $10 is the skill of "taming the ticking time bomb" that has allow many of us to cruise for decades.

[Adelie]

Originally Posted by Terra Nova

. . .
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.

Given their age that's doing better than almost any other mechanical consumer product I can think of. The youngest engine is 33yr old, the midpoint of production was 55yr ago. And half of them are still running. That's a really good product.

[a64pilot]

I admit to not reading the whole thread, but engines are my specialty.
My opinion is if the owner is mechanically inclined the A4 can be an outstanding engine for a day/ weekend sailor.
It can be much smoother and quieter than a Diesel
It tolerates short runs without being fully warmed up better than a Diesel
The buy in cost is much less than a Diesel
It can weigh less than a Diesel, although many modern Diesels may be just as light.
Real simple straight forward design, just the thing for a learning want to be mechanic.
You do of course have to respect the dangers of gasoline, just like Propane, they are both very dangerous

[Terra Nova]

Wow! Four moderators in a row finding the need to show support for this virtual antique!

Guess this must be quite an engine.

[Adelie]

Originally Posted by Terra Nova

Wow! Four moderators in a row finding the need to show support for this virtual antique!

Guess this must be quite an engine.

3 moderators, I posted twice.

[Hudson Force]

Originally Posted by Terra Nova

Wow! Four moderators in a row finding the need to show support for this virtual antique!

Guess this must be quite an engine.

It was a great engine when I was in my twenties and without very much money, but not my choice or my favorite, though it was a fine replacement for the one cylinder 8 hp Palmer on my first liveaboard cruiser.

Some of us starting out cruising right out of college when we are first employed or scraping together what we can for a cruising kitty are not selecting the most robust or expensive engines, but something more like what we had at the back of our VW "Beetles".

[Group9]

I had an A4 in my 1977 32 Islander. For a gas engine, they are okay. Simple and easy to work on. The same engine that was in Willys WW2 jeeps basically. Moyer Marine will go in your speed dial. Diesels are better.

[30yearslater]

Here is an overlooked issue. Load arm. The A4 weighs in at 310 pounds. A direct replacement Beta 14 weighs in at 196 pounds. The 114 pound difference seems minimal yet when considering the location in the bowels of the boat the loss of the weight down low will affect the CG of the boat. I considered a change out of my A4 for the Beta but I can replace the A4 1.5 to 2 times for the cost of the Beta. It isn't a quick switch out as muffler, high rise manifold, exhaust fitting, additional tank fitting for return, exhaust hoses at 2" instead of 1-5/8" plus hoist in and out. A basic beta engine and transmission only hits $8100.00 while a new block, manifold, head, etc A4 from Moyer is $6875.00. That includes electronic ignition with electric fuel pump and oil pressure cutout. A few upgrades make better sense than going diesel. With reasonable care a gas engine is no more dangerous than a diesel. In fact I've been privy to a sooted diesel starting a fire and can't say the same about gas.

[Scot McPherson]

Originally Posted by sailortype

interesting points re the A4 bearings Jim. Probably for sure these engines were never meant for long term long distance cruising. And the price difference alone for long distance cruising makes repowering a lot of sense.
But again, point well taken... although 'gas fumes are a major cause of boat explosions'... boats with A4's are not regularly blowing up despite all the horrible maintenance. Do we know one that blew up..?
A well installed well maintained gas A4 is 'safe'. To be sure, gasoline is not SAFE, nor is boating for that matter. All sorts of varied accidents and fatalities.
Nor is hockey... I was injured three times this year, but I am not going to switch to diesel hockey.

@Boatpoker... "engine compartments with grills at the companionway venting into accommodation spaces,"
Most of your examples are more than obvious dangers, but I do not get this one. In most boats, the engine compartment and living areas are just one big happy space via the bilge. Engine compartments are rarely sealed off from the cabin and gas fumes if any, being heavier than air, end up in the bilge and therefore in the cabin area. What is the issue here..?

Those methods for gases to ingress into the cabin are considered baffled. They do have ingress and egress back and forth from engine compartment to cabin, but it's not free flowing access. A buildup of gasoline fumes is still highly possible in the engine compartment without your awareness of it in the cabin because the diffusion of the gasoline fume through the baffles of the bilge etc. doesn't let it flow freely out and there may not be enough concentration of gasoline fume to smell it in the cabin despite there being plenty of fume in the engine compartment for ignition.

That's why blowers are so important so you can replace the air quickly before more fume can build up. I can't remembers the recommended air exchange rate, but it's like a full exchange of air within a few minutes if I recall before attempting to start the engine or use any other system that could ignite gasoline fumes.

[sailortype]

thanks for that info Scot... who knew?

[kmacdonald]

Originally Posted by boatpoker

I've surveyed hundreds of sailboats with A4's .... never seen one safely installed. Everything from engine compartments with grills at the companionway venting into accomodation spaces, the back side of AC outlets exposed to the engine compartment (many with solid copper wiring). automotive non-ignition protected battery chargers, automotive carburetors, un-grounded fuel fill fittings, un-grounded fuel tanks, Battery chargers mounted directly over batteries, fuel fill hose resting on exhaust manifolds, cracked copper fuel lines, the list goes on and on.
I repeat .... hundreds of surveys with A4's, still have not seen a single safe installation.

I would guess that these boats met CG standards when built. What changes were made since new I don't know but I suspect a lot of the explosions were not accidents. A safe A4 installation is not difficult to achieve IF you want it to be safe.

[Scot McPherson]

Originally Posted by sailortype

thanks for that info Scot... who knew?

anyone who has a skippers license ;-P

It's on the test.

Inboard gasoline engine compartments must be evacuated with a full exchange of air with a blower before you start the engine.