Replacing an Atomic 4 engine with a Diesel in Vancouver - Page 2 - SailNet Community
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post #11 of 13 Old 12-04-2013
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Re: Replacing an Atomic 4 engine with a Diesel in Vancouver

eeeeeeeeeeeeeeeeh you can get away with even less psi! just throw in some marvel mystery oil like moyer likes and shell be purring away in no time

honestly unless the head is severely cracked(youcan jb weld them nicely too) or the exhaust needs complete replacement or you are missing the water pumps or big parts a simple overhaul:

like lapping valves, chainging seals, gaskets and a cleanup of the piston tops etc...will yield you a good more years...

a nice tranny adjustment and new oil there does wonders for shifting too...clutch is easy to adjust too

what else?

oh new fuel filter and hoses will help the carb run nicely, if you have points and condensers a simple conversion to electronic ignition like prestolite or the one moyer sells works too

tired on an atomic 4 go hand in hand...most are tired, but MOST are still working away like a tank...

all good!
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post #12 of 13 Old 07-17-2018
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Re: Replacing an Atomic 4 engine with a Diesel in Vancouver

Most A-4s can be rebuilt the 1st time around without even so much as an over-bore. The low compression is gentle on the cylinders. Marvel Mystery Oil removes carbon deposits and insures the comrpession stays nice and low. Because it is an old "L" head design the valves run cooler than in overhead designs and there is no long valve train to wear. There were more than 40,000 A-4s put into MOST of the small production sailboats. They have outlived MANY of the diesel options available at the time as well. One notable Canadian diesel manufacturer stopped supplying parts to the engines they provided as options leaving many with nothing to do but get rid of their engines for fear that the next breakdown would leave them stranded needing an entire engine replacement. That corporation was the most prevalent supplier of options diesels at the time as well. So those who ordered their boats with A-4s avoided that issue. Many parts are still available for the A-4. The increase in re-sale value a diesel replacement provides is never anywhere NEAR the cost of the replacement and about the best one can hope for is a 40% price recovery at resale with most taking far less. The only real place anyone is going to see any cost benefit from a diesel is in fuel economy. You have to do a LOT of motoring to get that as well to actaully offset a substantial portion of replacement costs. With the arrival of bullet proof solid state ignition systems, converting an A-4 to one of those ends a huge part of the dependability issues inherent with gasoline engines. As far refreshing an A-4 goes one owner was quoted a price of 8,000 dollars from the yard. He took his out and back home and spent 800 dollars under the guidance of Moyer Marine. That spring he installed the engine and it ran like new. A BARE, rebuilt, short block with pistons, crank, valves and bearings all spec'ed out runs 3,500 dollars from Moyer Marine. Needless to say, a completely NEW A-4 costs every bit what a replacement diesel can cost and then some in many instances. The A-4 is rated at 30HP at 3000 RPM. One matched to a proper prop will never spin over 2500. Many of the stock props were horridly over pop for tehe A-4. Indiego sells one specifically designed for the A-4 that simply can not be beat. The A-4 is EASY to rebuild with simple hand tools and a low speed drill and cylinder hone are that is needed even if the rings do need to be replaced. Considering the age of most of the boats these engines were offered in, getting any real value out of a diesel this late in the game for them is simply never going to happen in most cases for various reasons. This is why so many A-4s will probably live on for another 45 years. Increasing the compression for performance is an A-4 killer. There are no center crank bearings in the A-4. Increasing cylinder pressures is a very stupid thing to do with one. Speaking of crank shafts though. So many were stockpiled because the only way to really break one is to flood the cylinders by over cranking, that those can be had for a scrap price. I have never heard of one needing to be replaced or ground unless somebody ran without oil.
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post #13 of 13 Old 07-17-2018
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Re: Replacing an Atomic 4 engine with a Diesel in Vancouver

This is from Moyer's web site:

Complete exchange engine options:
$5375 (late model direct drive)
$5430 (2:1 reduction)
$5430 (v-drive)
These prices do not include a $700 core charge which is refunded when we receive your rebuildable engine in our shipping container.

I have nothing but positive things to say about my A4s, (I had one in my Catalina 27 and now one in my Morgan 33). I found that using Marvel Mystery Oil not only kept the cylinders clean, it is also a top cylinder lubricant that helps seat the valves and seems to minimize combustion chamber wear. I wouldn't leave the dock without it.

A couple weeks ago, I noticed my oil pressure was down to just 25 PSI, which is a big drop from where it usually sits at 40 PSI. I was beginning to worry, then checked my log book and found that I was about 50 hours plus overdue for an oil change. After changing the oil, I went on a short trip and the pressure was right back up to 40 PSI.

Also had some starter issues, which turned out to be low battery voltage - I guess 7 years is a lot to expect from my Trojan T-105s, especially considering how much they are abused by the owner. I can buy these locally for $129 each. The biggest problem for this old codger is lifting them into the boat, down into the cabin and placing them into the battery compartment. Guess I'll have to round up one of the youngsters in the marina - they're a lot stronger than me.

Next season, I'll change the water pump impeller, which is now on it's 6th year. Those Obendorfer pumps and impellers wear like iron.

Good luck,

Gary
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atomic 4 engine , diesel engine , repower , vancouver

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