Running engine for long periods of time

[dtodd55]

I'm a new Atomic 4 owner on a 30’ Pearson sailboat and I was wondering if anyone had any advice on the reliability of the engine, and with running at full throttle for long periods of time. I intend to move the boat 30 nm in the spring and I'm new to sailing and probably not going to use the sails right away.

Do you recommend just below full throttle? Take a break every hour?

Can I run the engine at full throttle for 6 hours straight?

Under fair conditions, can I actually expect to get my max speed of 5 knots at full throttle?

How finicky are these engines? Can I expect it to conk out on me half way through the trip?

Thanks in advance for any advice!

[Marian Claire]

Welcome to the forum.
1. I have run my A-4 for 8+ hrs a day, day after day, at a RPM that gives me 80+-% of hull speed. A lot of things play into performance and every boat is different.
2. You should be able to reach a good/useful/efficient speed below WOT, wide open throttle.
3. I do not know.
4. You should reach it at less than WOT. But again you have to consider, prop size, how clean is the hull/prop, how "tired" the A-4 is etc.
5. Give an A-4 gas, compression, spark and proper timing and they will run. Tough little beasts.
6. You never know. There are many things that can go wrong on any engine.
I always have a "what if plan" going on in my head. My A-4 has limited the times I have had to use them.
Dan S/V Marian Claire

[Rbyham]

With some frequency I run my A4 for full days on the ICW. She is vintage 1966 and never misses a beat on such trips. I almost never go WOT. But I am not a pusher. I baby her and find a comfortable speed at what feels like about 75% of WOT. I don't have a tach so not sure of rpms. I do have temp and oil pressure gauge that I keep an eye on whenever motoring. If I get back to slip after several hour hard run (against tide for example). I will let her idle at the slip for a few minutes. My temp gauge never goes above 140 no matter what I do but I still like the thought of letting her return to regular temp and pressures. Bottom line I have no fear of all day runs but like others I typically have a plan B in my mind just in case. I would sure have sails on the boat in case.

[romantic comedy]

it is a great marine engine. I have run mine for 30 hours straight. There is no reason you would have to take a break. Maybe you could check the oil as you get to know t he engine.

Keep it in tune, with good gas and it will keep running. It has a simple carb and ignition system. The same type that was used on cars till the 80s. So breakdowns can always happen to any mechanical device, but I dont worry, I keep prepared.

Learn the engine and care for it..

[BunnyPlanet169]

Learn the engine and care for it..

Welcome to the forum!

The magic for you is the delta between where you are today, and where you will be in a few months of learning and caring. With care, the engine is reliable and forgiving, with readily diagnosed problem modes.

If the PO (previous owner) took care of the boat and engine, you should have no problem if you use clean fuel, perhaps new filters?, and watch the vitals of temp and oil pressure. If the PO didn't, then you will want to learn a bit first and think of contingency plans....

If you didn't find one onboard, I'd strongly suggest you get 'The Manual' offered for sale by our host. It's the best single source of information on the A4, followed/augmented by this forum. The manual is faster to read...

P.S. Bring the sails, and bring a friend who sails. You own a sailboat, and there's nothing better than being able to unfurl the jib and sail away from a potential problem. A sailboat without sails is crippled. Also, first year or two, a membership to BoatsUS is cheap insurance for the towing option alone. A commercial tow can be $500 - $1000. If available. If it's not an emergency. If it's not a salvage operation.... Be self reliant, but BoatsUS is AAA for the cautious.

[TomG]

dtodd55,

What shape is the engine in? Has it been maintained well? Is it original to the boat? Do you have compression numbers? How's the exhaust system? The fuel system? Any upgrades to the A-4? Do you have a picture?

As others have already mentioned, the A-4 is a very dependable and durable marine engine. A couple of "personality traits" include:

1. The updraft Zenith carb really loves good clean fuel. I think clean is more important than fresh for this carb. A good fuel filtering/polishing system will likely save you some fuel-related issues.

2. The valve springs on the older engines are not quite as strong as they could be. Given the marine environment and flathead engine style, sticky valves are not uncommon. The addition of Marvel Mystery Oil (MMO) to the fuel (usually at 100:1) plus the direct squirting of MMO into the cylinders greatly mitigates the potential for stuck/sticky valves. (This is why I was asking about compression ratios)

3. There can be corrosion issues with the A-4 as there are with any Raw Water Cooled (RWC) marine engine.

4. The water pump can be a challenge to remove without the "extendo-bolt".

There are others I'm sure, but the A-4 is a marvelous and robust marine engine. I invested a little time here on this forum and read the Moyer Marine Maintenance Manual when I got my boat a few years ago and have been wonderfully happy with my A-4. With MMI providing parts and service (Ken and Don are truly magnificent gentlemen) and this forum so wonderfully shepherded by Moderator Bill, I can replace, repair, or upgrade any system on my A-4 that I choose. There is a wealth of knowledge, and not just A-4 related, that makes this forum a place I visit all the time even though my A-4 runs perfectly.

Welcome aboard.

[JOHN COOKSON]

55
Welcome to the forum.

If you raise the main sail before you start your motor sail you will have a lot more comfortable ride. If the wind is favorable the main sail will help push the boat along. If the wind is "on the nose" or if there is no wind having the main up and sheeted in will help to keep the boat from rolling as much.

Most sailboats have low initial stability but high final stability. That is it is easy to heel them the first ~10* but after the initial heel it takes a lot more force to get them to heel more. This comes about because of the "wine glass" shaped hull.

Anyway having the main sail up will dampen and cut down on the down on the first ~10* of easy rolling motion. Try motoring with and without the main up. You'll see.

TRUE GRIT

[smosher]

I have a 74 p30 and at 3/4 throttle I can easy do 6 kts with a clean bottom and the indigo prop. I have run the motor for more than 6 hours with no trouble. There are several items though I would consider.

First I would replace points, if you have them, plugs, fan belt and change the oil. Not too difficult in the p30

Original Motorola Alt only puts out @ 13.2 vdc, If you have the upgrade to a new alt the voltage would be 14.4. This is an issue with EI and it will heat up the coil more as the dwell is longer. Many folks use a ballast resistor to drop the amp flow through the primary side of the coil. I personally have had a pertronix coil die even with the resistor. I haven't had a problem with the new coil from Moyer and its been 2 seasons.

After running for several hours with 30 wt oil, the oil pressure will drop
when you drop into idle. I use 10w 40 and the pressure stays at 40 psi.

If its the original fuel pump, the membrane cracks with age and pumps gas into the crankcase. I replaced mine with the electronic fuel pump, or you
can rebuild it with a kit from Moyer

When beating into the wind and waves the p30 will bob around quite a bit. As John stated run with the main up and to an angle to the wind, this will stabilize
the movement.

Its a good sturdy boat that is fast to sail. At my marina there's a few who race, I don't, and I overheard them that they can't beat the p30.


Steve

[Ajax]

I'll be the lone dissenter.

The boat is new to you, so you don't really know the maintenance history or what condition the engine is in. A healthy Atomic-4 will do this with no problem, but are you really willing to "put the hammer down" on an engine that may be tired?

I wouldn't run the engine at "WOT" the entire time. It's inefficient, and only shortens the intervals between major maintenance.

"WOT" on a Pearson 30 only gives you that last .5 knots of hull speed.
75-80% throttle will get you most of the way there, with a lot less wear and tear on the engine, and much greater fuel efficiency.

As someone already mentioned, a clean hull and propeller will greatly reduce the load on your engine. With a healthy engine and clean hull, you should be able to achieve at least 6.6 knots in a neutral current and no wind.

80% throttle should get you to 6 knots if the hull is clean.
No, you shouldn't need to give the engine rest periods. It'll either make the trip or it won't.

[ndutton]

It's not about trusting the engine but rather trusting the care and maintenance by the previous owner(s). Before I subjected a new-to-me 30 or 40 something year old raw water cooled marine engine to prolonged runs - or even short runs for that matter - I'd give it a full maintenance following the protocols laid out in the Moyer Marine manual and the advice available on this forum. I'd also examine at least four ancillary systems critical to the engine but not part of the engine itself: fuel, electrical, cooling and exhaust.

Make this engine your own and it will serve you well. Trusting the previous owner is a gamble.

[Ajax]

Ok Neil,

You were able to better articulate my thoughts on the matter better than I can.
...which is why I shouldn't be on the internet dispensing advice.

[ndutton]

While maybe not on exactly the same page we were certainly in the same chapter.

...which is why I shouldn't be on the internet dispensing advice.

Oh no you don't. You're not getting off that easy. If you don't chime in we are left listening only to blowhards with over 5,000 posts. Nobody wants that.

[Al Schober]

Welcome to the forum!
I have a '73 Tartan 30 with a '76 Atomic 4 (original developed a crack in the block). As the engines age, there are certain things that can be expected to happen. Rings will wear causing loss of compression and smoke in the cabin, valves and their seats will degrade causing loss of compression and hard starting, exhaust systems have a finite life - the list goes on..
Good points made so far. All I'll add is to carry some spares - electrical parts including a coil, fuel filters, pump impeller - stuff you can't fix. Burned points can be cleaned up, but if the condenser dies you need a spare. You get the idea...
The engine will run happily until it runs out of fuel. An 8 hour day is no problem. You're not going to need or want wide open throttle. The engines with 1:1 transmission are limited in RPM by the propeller. You'll find you'll get to a certain throttle setting and the boat or engine won't go any faster - back off a bit from there and things will stay happy. Keep an eye on your water temperature and oil pressure.
Hope this helps.

[joe_db]

Back in the day we ran the A4 at full throttle until the gas was low, dumped more in while still underway, and kept going. Probably 300 miles without a break. Fast forward some years and eventually the engine could not be run hard for long without overheating and losing oil pressure. When I removed that engine we took it apart and the block had rusted badly which clogged many cooling passages.
So.....you may have a great engine or it might overheat and/or lose oil pressure if run hard for a long time, depending on where it is in the A4 life cycle. I would suggest running for an hour at 3/4 throttle and watching the gauges to get an idea.

[JOHN COOKSON]

How finicky are these engines? Can I expect it to conk out on me half way through the trip?
Thanks in advance for any advice!

Engines aren't finicky. People are at times. As in when I do it it's called discriminating. When you do it it's called finicky.
In any case getting to know the person (or engine) well will reduce the chances of an unpleasnt encounter later.
Once you have the engine cruise ready I would recommend a one hour motor sail close to home port to be sure as possible that there will be no unplesant surprises.

TRUE GRIT