Atomic 4 Owners

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Jan 22, 2008
250
Cherubini 37c HULL#37 Alameda
I'm looking at a Islander 30 MKII w/an Atomic 4 gas motor. I'm looking for feedback on reliability, availability and cost of parts. Also, are there any inherent problems I should be looking for?
 
Oct 26, 2005
116
Oday 28 Detroit/Grosse Pointe Park (O'Day 192, O'Day 28)
moyermarine.com
I race in a fleet of about 18 C&C 35s, all with Atomic 4s from the early '70s. While we do have some problems, I think that's to be expected from a 40 year old engine, and most of the time they're easy to fix. Moyer is very helpful, and will talk you through most problems over the phone. Also, he has a very helpful book for maintenance, troubleshooting and repair. He recently announced that they've found someone to cast new blocks, so that's a good indication that the engine and parts will be available for a long time.
 
Mar 8, 2011
296
Ranger 33 Norfolk
All of the issues I have had with mine are fuel related. I have used almost no gas in the nearly 2 years I have owned my boat. The ethanol holds so much water in suspension from sitting that it is rusting steel parts of my fuel pump, oxidizing aluminum valve bodies in the pump, and turning my float green and cruddy. . .

I've cleaned it out numerous times and rebuilt the fuel system once. I'm down to putting 2-3 gallons in a portable tank and dumping whats left over every 30 days :doh:
 
Oct 2, 2006
1,517
Jboat J24 commack
The issue is saltwater boats with raw water cooled blocks are getting pretty near the end of the motors life due to block rust through

A saltwater boat with a freshwater cooled block can last almost forever
 

Ross

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Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
I absolutely don't accept the ethanol/water argument as valid. If you are getting enough water into your fuel system to create problems you no doubt have a point of water intrusion. I use motorcar fuel in all of my yard equipment and save the fuel from one season to the next there is never any problem with starting or running. My cars have been allowed to sit for several months at a time with no fuel or starting issues.
 
Aug 29, 2011
27
Catalina 27 mobile
a 4 owner

The issue is saltwater boats with raw water cooled blocks are getting pretty near the end of the motors life due to block rust through

A saltwater boat with a freshwater cooled block can last almost forever
i have an atomic 4 in my cat 27.the water jackets can be cleaned fairly easily.there is a water jacket side plate under alternater.the problem is that those 8 quarter in bolts will break off in block if they are rusted bad.i broke 7 off in mine.if they do there is a kit on moyer marine to fix them,i did it a cheaper way.i drilled the holes out to 7/16 then welded 3/8 studs in hole.1/4 in bolts always break on me.i also removed thermostat and routed all water into water jacket side plate for maximum cooling.someone is going to tell me i shouldnt have done that but these motors didnt originally come with thermostats.the later models did.ok if the moter has been sitting up,or if not much water is being exhausted,first, take the exhaust manifol off and flush it good.u can flush it without romoving it, but it is probably so full of crap it wont come out unless u remove it.if it is indeed full of rust,then u definately need to remove water jacket side plate.clean all the crap out.remove and clean thermostat.moyers thermostats are pretty high so i advise boiling it and seeing if it will open,if it opens 1/4 in then its good because in engine it will have pressure from below and open fully.u may opt for no thermostat as i did.the water pumps are oberdorfer,take it out clean it if needed.inspect impellar. these are the easiest engines there to work on.basically it is the same as a 20s model a ford.u can crank it with a hand crank too.i turn mine over by hand and it cranks right up.i got carried away and didnt ask u if the engine runs.if u have any problems let me know k.
 
Aug 29, 2011
27
Catalina 27 mobile
they are really great engines,i love mine no problems with my fuel pump its mechanical.my gas has been there for 6 months runs great.but be aware that unlike a diesel,if gas leaks into bilge from stuck floats in carb,then gets shook up.there is danger.but good thing is u can smell it easily.
 
Mar 8, 2011
296
Ranger 33 Norfolk
I absolutely don't accept the ethanol/water argument as valid
I have two very in depth and long threads over on Moyer Marine detailing my nightmare, second one with pics :dance:

It could have just been dumb luck as far as fuel quality goes, but I've dealt with it and seen the results first hand more than once on the same motor :D
 

Ross

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Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
I saw an Atomic Four the other day with a wonderful glass sediment bowl. I haven't seen one in service for more than 30 years but they were always the first line of defence against water in the gaoline. If you buy 10 gallons of 15 percent ethanol gasoline you will be getting 1.5 gallons of pure ethanol. That could soak up 9.6 ounces of water and still be 190 proof alcohol or 95 percent. 190 proof alcohol is considered dry for the purpose of thinning shellac. You can wet black gunpowder with 190 proof alcohol and burn it off, when it is consumed the gunpowder will burn. Wet black powder don't burn.
 
Feb 26, 2004
22,759
Catalina 34 224 Maple Bay, BC, Canada
pk, am I correct in remembering that "your buddy" Steve on our dock has an Islander 30? Nice boat. (Before he got his hands on it!) :)
 

garyg

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Oct 14, 2005
22
Morgan 33 annapolis, md
Definitely log on to Moyer Marine web site that IS the source for all things Atomic 4, plus the forum is excellent with very knowledgable owners.

I have a 1970 33' sloop with the original A4. It pays to learn your engine like the back of your hand.
 
Jan 22, 2008
597
Oday 35 and Mariner 2+2 Alexandria, VA
Not to rekindle the ethanol debate, but cars are typically closed systems. They do not take in fresh air into the tank. Tank breathers use engine exhaust to keep the tank pressurized and reduce emmissions. On a boat, the tank is vented so ambient air keeps the tank from drawing a vacuum. This means that beautiful, damp, salty air is drawn into the fuel tanks, so we always have to worry about water in the tanks. I run a diesel and am surprised sometimes at the water that can get into the tanks. For an eye opener,drain a fuel tank and see what comes out!
 

RichH

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Feb 14, 2005
4,773
Tayana 37 cutter; I20/M20 SCOWS Worton Creek, MD
As another poster began to explain the prime cause of ultimate destruction of an A4 is internal rusting of the block (and exhaust manifold).
Don Moyer's time tested method of evaluation of the degree of rusting is to (either by yourself if able or by a surveyor - of course with agreement of the seller) is to remove one of the exhaust manifold bolts and go into the bore of engine block casting with a probe (metal dental pick works good) and actually count the number of bolt treads remaining in the casting. 4 or more threads remaining in that bore will indicate that there is 'plenty' of casting left .... so even in the worst case later on, there will be 'enough meat' for repair/rebuild. With less than 3 threads the casting generally is 'too thin'.

Against all intuition and because internal rust/corrosion is the prime cause of accelerated A4 life failure, the best old A4 will be the one that has had the most run-time !!!
When cast iron is routinely run 'hard and long' it develops a 'self-protective' form of rust - black rust or ferrous oxide. This is why naval ships rarely shut down - so that the protective 'black rust' is promoted and kept intact. This protective form of 'rust' develops inside an engine that is kept 'hot' and run hard.
Upon long term 'standing idle', or if the black rust is allowed to come in contact with humid air, the black ferrous rust will change to the more destructive form of iron oxide - ferric or 'red' rust.
So, if the previous owner has run the engine long and hard and often you can expect 'more meat' remaining. A somewhat important question to ask the previous owner is also: How do you store the engine for long term 'lay-up' or winter layup? What you dont want to hear is that the engine was drained and left with only air in the block and exhaust manifold .... the contact with humid air greatly accelerates the formation of destructive 'red' rust. If however the previous owner drained the water and then filled it with antifreeze (containing rust inhibitors) then you will probably have sufficient 'meat' remaining.
If the engine has 'sat around' or has had 'light usage' or was typically drained (and no antifreeze installed) then Id strongly suggest that you or a surveyor .... do the 'exhaust mounting bolt thread bore count'.

Of course if the A4 has been converted to fresh water cooling - FWC (heat exchanger added) then your investigation will probably find an engine with minimal 'internal rusting' ... a FWC with Heat exchanger A4 is the preferred old A4 to look for in a boat.

Good luck.
:)
 
Jan 22, 2008
880
Fed up w/ personal attacks I'm done with SBO
I'm an active member on the Moyer forum and we have recently discussed the ethanol "issue." There are two camps regarding ethanol: one blames ethanol for any fuel related problem, the other says "Hey, I run ethanol blend too, it sits for prolonged periods and I have no problems whatsoever. How come you and not me?" Pretty good question if you ask me.

There are ethanol related issues but it's more like it aggravates other problems.

  • If there's residual crud in the bottom of the tank, ethanol acts like a solvent returning the sludge into the fuel mix where it finds its way downstream causing problems. The bigger question is why the crud in the first place, that's not ethanol's fault.
  • Then there's the whole fiberglass tank issue mostly found on power boats. Gotta replace those tanks, no question.
  • As the A-4 hasn't been manufactured for a little under 30 years, the boats that have them are aging too. Some of these boats still have old fuel lines that are not alcohol tolerant and ethanol deteriorates them and yep, more running problems. If you know what you're putting in the tank, why wouldn't you make sure the fuel lines are capable of handling it? I did, replaced all mine years ago with Type A1-15 ALCOL and no problems. Again, don't blame ethanol for essentially a lack of maintenance.
Those that blame ethanol for everything have bought into the political argument that requires a lot of blind assumption. Truth is, give an A-4 good clean E-10 and she'll run fine. A dirty tank half full of water and rotting fuel hoses are your problem, not E-10.

Speaking of which, if there's so much water in your fuel it's causing performance problems you should listen to Ross and find the incursion. Usually it's the neglected O-ring on the fuel fill cap. There you go, one more owner maintenance problem that gets blamed on ethanol. What is the condition of the gasoline you're getting from the fuel dock? Any water in that? I NEVER use fuel dock gas, always buy it at the corner gas station and schlep it down the dock in 5 gallon jugs. I have no first hand evidence the fuel dock's tanks are contaminated but I don't trust them. Is ethanol to blame - AGAIN?

And a brief comment on A-4 internal rusting. Yes, it's true raw water cooled A-4's rust on the inside BUT at a much slower rate than you would expect. The engine was originally designed to be raw water cooled and the engineers had the foresight to cast the blocks with a high nickel-chromium alloy that is far more tolerant of salt water immersion than your stove bolt variety iron.

Fresh water cooling is really the way to go though. I made the conversion last year, pretty easy to do and not all that costly.
 
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RichH

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Feb 14, 2005
4,773
Tayana 37 cutter; I20/M20 SCOWS Worton Creek, MD
What OS stated .... and the engine was originally designed with a 'hefty corrosion allowance' - extra 'thickness' of metal to take care of the expected 'rust'.
 
Jan 22, 2008
880
Fed up w/ personal attacks I'm done with SBO
I'd like to make a case for an older boat with an Atomic 4 too.

I have an Atomic 4 in my boat and it's great! I'm careful about the fuel, no different than anyone with a propane stove and replace ancillary components as necessary. My fuel pump is electric, my coolant pump is also electric. I have a manual fuel shut off valve immediately ahead of the carburetor, always off when closing up the boat. It starts within a second regardless of layoff time or temperature, it runs smooth, quiet and doesn't stink.

And don't think I'm a diesel hater either. My previous boat had a Perkins diesel that ran well too, no problem there.

Because of the anti-gas engine propaganda, Atomic 4 powered boats can be found at very affordable prices.
 
Sep 25, 2008
2,288
C30 Event Horizon Port Aransas
I have a dock neighbor who has an atomic 4. He says he loves the power it has. I have also heard atomic 4's called anemic 4's. Are they super powerful or super weak?
 
Jan 22, 2008
880
Fed up w/ personal attacks I'm done with SBO
I have also heard atomic 4's called anemic 4's. Are they super powerful or super weak?
For its size, I think it packs quite a punch. Put it in a boat too big - like any small auxiliary - and you'll be disappointed. Same goes for a prop too big.

My Catalina 30 at 10,500 lbs. dry seems to be perfectly powered with the direct drive A-4. 33 feet and larger and you'll want the 2:1 reduction gear. On the Moyer forum we have some members with Hughes 38's that are happy with theirs.

The foregoing is dependent on the engine being in good tune, no exhaust blockage, carb in good adjustment, clean prop and so on. The vast majority of performance problems with these engines have to do with ancillary systems rather than the engine itself.
 
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