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Discussion Starter #1
We just purchased a 1978 Catalina 27 with a gas atomic 4. The boat is in very good condition, and has been well maintained.

I've read through a number of threads in this section regarding the gas atomic 4. There's some real back and forth on this engine!

On the one hand, there were posts, such as one from a surveyor, who commented that the atomic 4 on boats he's seen scares the hell out of him. That's not real confidence inspiring for us! And, is the nickname for the engine, the atomic bomb? Isn't that just great ;)

On the other hand, there are atomic 4 owners who say it's a simple, reliable engine. Though, they also recommend being careful to check for fumes -- turning on the blower and sniffing... and getting a fume sensor?

Well, we really like our boat, but we want, of course, to take appropriate safety measures. And, we'd like to have a realistic and balanced perspective. How risky is this engine? What is the appropriate perspective? What are the best practices regarding its use? Should we get a sensor? If so, what kind and where do we get one?

We plan to be diligent and follow best practices. And, now is the time for us to learn and begin to practice them. Thanks!
 

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Discussion Starter #2
Am just thinking... how about checklists, like used with airplanes? We could print these up keep on board.

Prior to starting the atomic 4.
After starting.
etc.
 

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YouTube - 2011_05010012.AVI

YouTube - 2011_05010014.AVI



I just updated my gauges



And cleaned things up in general

About 98% of the overall pleasure boat market is gasoline powered ;)

I would strongly recommend that the fuel pump be rebuilt as they are and old style unit with a single diaphragm and its the only real weak point in the motor

If your blower is working and you use it and take a sniff the risk is really LOW
 

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Discussion Starter #4
Thanks for your reply. I've noted your recommendation about the fuel pump and will look into the condition of the current one and possibly getting a rebuilt.

Re: the risk. That's good to hear. It's hard, w/out experience, to have a good feel for risk. There are certainly alarming posts... just read a few about refueling... making me wonder if I should get a remote control to start the engine from a good distgance after a fill-up.

I am thinking of getting the xilink (sp?) vapor sensor in the West Marine catalog. Maybe the one that can use 2 sensors -- one for under the engine? ... and one for under/near the fuel tank area? That would help w/ safety and also be a good excuse to get another gadget.
 

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While being careful and following procedure for fueling, starting, etc the Atomic 4, there is no reason to be paranoid. Regarding fueling, where is the fuel port on your boat? It should be located where no fumes can travel down into the bilge and probably is so situated. When I purchased my 1976 Atomic 4 equipped boat I replaced the entire fuel system, tank, lines filters etc and check them regularly for any signs if failure/leaks. Always use the blower for 5 minutes before starting (and I run mine for a few minutes after stopping) the engine.
What is nice about the Atomic 4 over diesels is they are much quieter and they don't smell so much. In a small boat, the diesel smell can permeate the entire cabin and it is very hard to get rid of it. Also, gasoline engines are much more suited to the short run times typical of most sailboats than are diesels.
The "bomb" appellation is totally undeserved. Boat fires are caused by several reasons, cooking fuel, bad electrical wiring, engine fuel, etc., so one has to be fire concious all the time. Just this week a shrimper caught fire in our marina and burned to the waterline diesel engine and all.
Enjoy your boat and your Atomic 4 and if you ever have to replace it look at the new diesels as they are much better engines than they were back in 1978.
John
 

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There are thousands of A4s out there and very few related 'explosions'. In fact, as a sailboat auxillary a gas engine makes much more sense than a diesel. There is an elevated safety aspect wrt diesel vs gasoline, but with proper equipment and practices it's quite doable.

FWC A-4s are preferred, the RWC versions are going to be more prone to cooling issues and corrosion.
 

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Most of the well meaning folks who say that the A4 and gasoline engines are dangerous (Atomic Bomb) most likely have diesel engines and may never have owned an A4.
Besides using the blower before/after running your engine as mentioned above, it is a good practice to ALWAYS shut off your main fuel petcock (valve) before you leave your boat. This insures that the fuel in your tank stays in your tank and does not find a way into your bilge. Of course, this means you will ALWAYS have to turn on the fuel valve when you get to your boat. It is also a good practice to shut off your raw water valve when leaving the boat and opening it each time you arrive.

If you haven't been to the Moyer Marine forums you owe it to yourself to register over there: Moyer Marine Atomic 4 Community - Home of the Afourians - Powered by vBulletin
There are a number of A4 owners over there who have owned their engines for many, many years and can offer assistance, if needed.
 

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I have an atomic 4 and I'd add that I'm not worried about the risk of gas vs diesel. I will say that I have had a lot of headaches with it and its not the most reliable motor. Am not an expert mechanic but it seams if its not one thing its another - very quirky thing starts up and runs fine one minute wont start other days no matter how much I troubleshoot the thing. I've never had a diesel though I crewed on a boat with one and it fired up consistently. This motor was rebuilt 8 years ago - I swear the engine only wants to run when its nice and warm and dry between the hours of noon and two and then its done for the day and wont come back to work. YMMV - I'd say I wish I had a different inboard - installed a honda outboard as a backup due to its unreliability.
 

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mariner you need someone to look into your problems. They need regular attention like any gas motor. You give it the attention, and it will be good to you. I live with the A-4 for 17 years, and the only problems I had was operator error........i2f
 

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tommays,
I am looking at replacing some gauges and am really impressed with your set-up. Can you tell us where you found that panel ? It's exactly what I'm looking for.

Thanks,
Kirk
 

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Two things I would add for the A-4. Get the Moyer service book on the engine,and get a carbon monoxide detector. I got the CO detector because the engine was 30 years old and stuff fails. As I was bringing the boat hom from the Chesapeake my daughter was sleeping below on the long power trip down Delaware Bay when the detector went off. The exhaust manifold was leaking and filling the cabin with CO. No one rode in the cabin until I got the boat home and had it fixed.
 

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rconn, the A4 was built from an industrial low-compression low-rpm engine that was designed to pretty much run reliably "forever" with routine maintenance.

Gasoline is supposed to explode. Most fuels are supposed to explode. The only danger is when you are sloppy with the fuel and it explodes OUTside of the engine.

So you check things over once in a while. Replace fuel hoses every 5 years or so with new alcohol-resistant ones because "real" gasoline is hard to find these days. Make sure everything is clean and tight. And because it has a carburetor and carbs need to be overhauled every 5 years or so also (because of varnish and clogging as well as adjustment) you also overhaul the carb if it hasn't been.

And yes, install a blower designed for use on boats and get real religious about running the blower for 5 minutes before you ever ever start the engine.

The fumes and explosions aren't a real issue, but every year there are thousands of accidents on the highway because people can't bother to put air in their tires, so they overheat and blowout. For THOSE people, an A4 would be a problem.

Moyer Marine is The Ultimate Source for things A4. If the carb has been overhauled and the ignition gets routine care, it should run forever. Of course old spark ignition systems means points, coil, condensor, etc. also are expected to be replaced from time to time, so even if your engine runs perfectly, you might want to get a set of ignition spares and pack them away so they will be on hand when and if you need them.

Diesels don't have these problems, no. But they have their own problems, like a stinky exhaust and problems with fuel contamination and growth. Ask any diesel owner if they've ever heard of someone having a fuel problem, air in the fuel, a diesel stink...Sure, it is harder to make diesel blow up but that's not impossible either. "Fuel air bombs" aka "hypobaric weapons" use diesel fuel because it can explode very very nicely.

Make friends with your A4, it really is a simple system and with routine care will work very nicely.
 

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Just a note. Moyer is producing NEW engine blocks for the A4.
 

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I replaced the A4 in my old boat when it stoped running.
the A4 always smelled like gas and used more than a gal of fuel an hour, the used diesel that i installed uses less than a third og a gal.
 

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Tommays.. those sheaves would really look nice in alum, SS or chrome LOL
 

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mariner, ive had a similar problem with my A4 on my 1975 C&C 27. i would be able to get it started and have it run to eternity at idle but after 15-20 minutes after running it at say about half throttle it would start to require a ton of choke. i'm no mechanic either but between the service manual and a friend's father, i figured out the problem. besides needing all new gaskets and a snapped choke shaft, the throttle valve inside the carb was bent to the point where it was flooding out the engine. after having hassles finding the new parts i went with a new carb which was easily ordered, i installed it and tested it out dockside and sure as the sunrise, it hasnt given me a problem yet. its a great engine when its running smooth and believe me i understand the frustration
 

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" the throttle valve inside the carb was bent to"
All part and parcel of the reason that carburetted engines just don't belong on boats. A carb is designed to be happy in a fixed, or at least, stable, installation. Bouncy-bouncy does not help the "clockwork" function properly inside a carb.
IMO, the best excuse for a diesel on a boat was that diesels were normally fuel injected while gasoline engines weren't, in past.
Of course the blessings of diesel stink, and high pressure fuel systems, and crud in the fuel tank, mean the old A4s won't be truly obsolete until the last one of them is abducted by aliens.<G>
Carbs, even in cars, should be stripped and overhauled every 5 years or so. Supposedly the "new" gasoline blends will extend that interval but I say that's spinach and I'm not having any of it.
 
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