Atomic 4 engine swap to diesel

K Day

.
May 26, 2017
4
Catalina 30 Cambridge, MD
Has anyone swapped out an A4 gas engine for diesel? What kind did you get? Can you get reconditioned engines? Any suggestions for where to look? (I'm in Maryland) Thanks!
 

SG

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Feb 11, 2017
1,670
J/Boat J/160 Annapolis
There is a Universal 23 or 25 HP that is pretty equivalent; however, I think the issue is the clearance for the Catalina 30's available space under the dinette. You need to look closely at the vertical clearance as well as the horizontal access issues.
 
Sep 8, 2014
2,551
Catalina 22 Swing Keel San Diego
Beta Marine has a line up specifically for Atomic A4 swaps, but like SG mentioned you have to pay attention to vertical clearances since the diesels are taller.
 

K Day

.
May 26, 2017
4
Catalina 30 Cambridge, MD
Thanks--I've read that there are some adaptations in the dinette seating. Is it possible to get reconditioned Universal 23s or 25s? With installation costs, I've heard it will be around $8K, and I paid $7K for the boat....that either makes it a good deal or else an argument to sell and buy a new boat!
 
Feb 6, 1998
11,701
Canadian Sailcraft 36T Casco Bay, ME
Why would you want to re-power an A4 to diesel, on an old 7K boat that will still be worth about 7K after a re-power...? Just get a rebuilt A4 from Moyer, drop it in and call it a day.. MUCH LESS EXPENSIVE.....
 
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SG

.
Feb 11, 2017
1,670
J/Boat J/160 Annapolis
The dimensional issues are also horizontal and involve access considerations and clearances.
 
Feb 8, 2014
1,300
Columbia 36 Muskegon
Moyer are the world's experts on the A4 and have everything needed to keep one running. And they're great to work with.
 
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Feb 26, 2007
11
- - Long Beach
KD,
Why are you looking to swap? A4's are hard to kill and Moyer Marine has everything you need to rebuild one. Why not take the money you'd spend on a repower and buy a boat equipped like you want and sell yours? Not a fan of having gas on board but you're talking a whole lot of work for not much gain.

Once bought a Morgan real cheap because the Atomic 4 wouldn't run. Previous owner had mechanics telling him the engine was shot and needed to be replaced to the tune of thousands of dollars. I bought it and replaced a clogged wet exhaust with stuff from a big box store and a little work for about $40 and the thing ran like a top. Not knowing how to fix things on your boat will be very expensive.
Good luck in whatever you decide.
 
Jul 6, 2013
223
Catalina 30TR, Atomic 4 2480 Milwaukee
My '82 A4 runs like a top. I put the boat in the water last week after winter storage, and the engine started on the first crank. Occasionally, I buy a part from Moyer to keep it in top shape.
But if I were faced with a re-power, I think I would move on to a different boat. Even a rebuilt A4 is $5k.
 

K Day

.
May 26, 2017
4
Catalina 30 Cambridge, MD
I bought the boat cheap ($7K) from a guy who knew a lot about the engine but I don't. The A4 has just been unreliable and it's no fun being out on the water not knowing if you'll be able to motor back to the slip....If a rebuilt A4 is $5K and a diesel replacement is $8K, we're still ahead of the game in terms of buying another boat. We really couldn't get another Cat 30 for less than $20K--right?
 
Jul 6, 2013
223
Catalina 30TR, Atomic 4 2480 Milwaukee
I bought the boat cheap ($7K) from a guy who knew a lot about the engine but I don't. The A4 has just been unreliable and it's no fun being out on the water not knowing if you'll be able to motor back to the slip....If a rebuilt A4 is $5K and a diesel replacement is $8K, we're still ahead of the game in terms of buying another boat. We really couldn't get another Cat 30 for less than $20K--right?
That's a good point.
You can download the A4 service manual from the Moyer website. That may give you some clues about troubleshooting. Or, a mechanic might be able to get it running well for a few hundred $. This is a well-known engine, and very basic.
But if you really want a diesel, then go for it. Your boat.
 
May 20, 2016
3,015
Catalina 36 MK1 94 Everett, WA
A4's are fairly simple motors - If you've adjusted the valves, set the timing, new plugs, and still not reliable - rebuild the carb. A tach dwell meter and timing light is a must. Set your points by dwell not spacing and you'll do much better - remember you can set the dwell with the distributor cap removed and cranking (close raw water pump). These days it might be even better to get electronic points replacement (not available when I was playing with them).

Les
 
Jan 18, 2016
782
Catalina 387 Dana Point
What LeslieTroyer said. A4s are pretty good engines. Figure out if your problem is fuel or spark and fix it.

Ignition: There are electronic ignition kits available. Moyer sells a complete Pertronics distributor or a module for the original Delco or Prestolite distributor. Indigo also sells a kit for the orig distributors.

Fuel: New carbs are widely available. Moyer sells em, but they're basically a tractor carb and can be found all over. If you have the original mechanical fuel pump, that can be a problem - the fix there is to replace with electric. May want to change your fuel filters too.

How to DX: Maybe list some of your symptoms here or on Moyers' forums. If it's a no-start dealie, the easy way to tell if it's fuel is starter fluid. If it starts with fluid you know ignition is good. Intermittent ignition will feel like you turned the key off. Intermittent fuel feels like a miss or a stumble. The A4 isn't much more complex than a lawnmower motor - any oldschool mechanic can fix em. Those of us that own old boats need to become pretty good at turning wrenches.

A new beta will be over $8K for just the engine, and it may be too tall. You also need to change out a bunch of fuel parts, the prop, and for the beta they want a bigger diameter exhaust line. I dunno where you can get a diesel swapped in for $8K - if so that's a screamin deal.

Easiest way to repower an A4 powered C-30 is to buy a different C-30. There's hundreds of them for sale, many under $20K. Or go ghetto and hang a 15 horse outboard on the back,
 
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