The coupling on a 2 to 1 Atomic 4 installation
has 4 bolts. 1/1 is 3, I believe. So that is an easy check. Or you can put it in gear, mark the shaft, and turn the engine over exactly one revolution with the hand crank. If the shaft mark is right back where it was, you have the 1-1 transmission
. If it is halfway around from where it started, it is the 2.05 or whatever to 1. No crank? You can use a 1/2" drive ratchet and I think about a 13/16" socket. Grind two slots for the crosspin on the flywheel shaft. For easier turning, remove the spark plugs. Good excuse to check them and/or replace them.
I don't think the 7/8 shaft should be a major problem with most common A-4 replacement diesels, but certainly a 1" shaft would be preferable. Make sure it will fit before you go for it, though.
I don't care for gasoline engines. Yet, I have an Atomic in my liveaboard Cal
2-27. I would love to repower
, but then my new engine will cost about 4 times what I paid for the whole boat, Atomic 4 included. So we have an uneasy coexistence. The Atomic is quieter than just about any diesel
, with no perceived vibration. Gas is always easy to find, when inland or coastal cruising, than diesel. If nothing else, I can wade ashore with a suitable container and walk to a gas station. Oh, and my motor
is raw water
cooled. A disaster waiting to happen, after almost 40 years of having seawater pumped through the block, but so far so good. A diesel is cheaper to run, but I only use the A-bomb to get in and out of the marina, and I probably burn about a tablespoon of gas doing it, so no biggie. As long as it keeps running after a fashion, I won't replace it.
My suggestion, then, unless you are paying enough for the boat that $8,000 or so for repowering is small potatoes, or unless you do a lot of motoring, is if the Atomic runs okay, just keep it in good repair until it seems to be not up to the task anymore. And since you will already be carrying a tankful of gasoline, you have a good excuse to buy an 8hp kicker
use, and an outboard
mount for it. Then if the A-bomb goes boom or clunk or whatever, you can at least finish motoring back into your slip with the outboard
. A gently used outboard can always be sold, if you later on go ahead with a diesel replacement for the Atomic.
Give the atomic a good evaluation before you make up your mind to get rid of it. In other words, it it ain't broke, don't fix it. If it ain't broke, don't break it, either.