Originally Posted by jeepbluetj
Don't fix it if it ain't broke.
The a4 will go thousands of hours easy. And you'll know when you need to rebuild it. Low compression, water in the combustion, etc... All the typical gasser failures will tell you when/if it's done for. Then you can buy a NEW one for $4K and drop it in (moyer is casting new blocks/heads/etc...)
Electronic ignition is a good thing on this motor.
Electric fuel pump
is a good thing too.
And yup - it's a teeny little flathead motor. Valve adjustment through the side of the block.
New blocks? Wow that's good news. Everybody seems to have tons of crankshafts and rods and pistons and stuff.
OP, at this point it might be shutting the barn door after the cow got out, to convert to freshwater cooling. 40 years of seawater cooling will have done enough damage already. If you are already freshwater cooled, then that is a definite plus. One thing I do recommend though is replacing the mechanical fuel pump with an electric one. The diapghram can fail and send gasoline into the crankcase. That isn't good. Oh, and the Moyer Marine electronic ignition add-on is a good move. Definitely improves things. No more worries about damp points, etc.
Most Atomics out there have NEVER been rebuilt. They wear sowly. The most common atomic killer is the raw water
cooling. Eventually corrosion
eats into the block and you got water on the pistons or in the crankcase.
My A4 spent considerable time under water under previous ownership
, post-katrina. This would be a death blow to most gasoline engines. After sitting unused for years, I bought the boat and the engine actually turned over with the starter, when I connected my pickup battery
to it. That was the deal maker. I figured I could get it running if it wasn't solidly froze up, so I bought the boat. Took a while to get it actually running, though. Now, it runs, and yeah it is a little cranky sometimes, but the only reason I am fixing to get rid of it is my fuel tank
has a hole in it and I can't get to it without pulling the engine, and I have been wanting to go electric for a long time anyway. After 40 years of hard use and harder neglect, it still runs and it could still replace a busted engine in a beat up old boat that you wouldn't want to put a new motor in. They are great, simple engines.
If your oil looks good and a magnet doesn't pick up any shavings and has no water or foam in it, and it starts and runs okay, and has good compression, I say don't worry about a rebuild, ever. You can get a compression gauge at autozone and do your own compression check. The gauge just screws into the spark plug
the pressure at idle and the 4 cylinders should be within about 20% of each other.
You do need to tune it up every year or so. If you have regular point type ignition, anyway. For that you COULD do it by ear, but you SHOULD use a timing light and tachometer. Cheap
at autozone. Make sure it will work with a 4 cyl motor. Moyer Marine is a good source for the detailed how-to. If you have electronic ignition, just replace the plugs every 5 years or so. Serious. With electronic ignition it is set and forget.
Do you have a separate fuel filter
/ water trap? You really should. And check the engine mounted filter. In fact, replace it or remove it altogether if you have a proper filter setup down there.
Replace your belts and hoses, especially fuel lines, with good quality stuff, every few years. Make sure your fuel lines cant chafe on anything when stuff is getting all vibratey down there. A catastrophic fuel leak is a major problem with a gasoline boat. You really really need to have spare belts and filters.
Change the oil. There is no oil filter
on an atomic so oil changes are very important.
If you decide you don't want gasoline on your boat, which is a legitimate concern, A Beta 10 is pretty much a drop-in replacement diesel
. Very little to do beside simply replace the engine. You will need a return line to the fuel tank
, freshwater cooling setup, thats about it. I am going electric, but that isn't for everybody. The Beta is cheap
and for most parts you just go to a Kubota tractor dealer.
Good luck with the A4 and do visit Moyer Marine's website and get all the manuals
and stuff, even if you elect not to go with the upgrades I mentioned. Unless the block gets ate up from the inside out from raw water cooling, they are really long legged engines with a long lifespan.