View Full Version : Detroit diesel 671 rebuild

05-16-2010, 10:09 AM
Has anyone here ever rebuild a Detroit diesel 671?

I am trying to decide if rebuilding a 671 or repowering with a 6BT is a better idea.

05-16-2010, 03:42 PM
I.ve done an in frame overhaul on 6-71's. Make sure you shim the liners to the right height. Pistons load from the bottom of the liner and go in with the liners. I.e. rod end is to big to go in from the top. Make or buy a liner puller. Nothing like a 6-71 at full power, at least for sound. have twins in a small loco application.

05-17-2010, 07:41 AM
It seems to me that you remove the intake and exhaust, pull the head, pull the oil pan, unbolt the rod caps, drive the pistons and liners up as a unit by inserting a tool across the air holes in the liner and rotating the crank and you are ready to start dropping new piston and liner kits in, new bearings and reassemble - shimming the liners, setting the racks and valves, etc.

It just does not seem like rocket science to me and I can not understand why shops charge over $2K per hole, the lowest quote I got was $15k per engine. Complete rebuild kits run about $200 a hole, so lets say $1500 for eevrything, that leaves $13500 in labor at $65 an hour (the posted rate) would be 207 hours to do what looks to me like less than 40 hours work.

Frankly long beffore I would spend that kind of money to have a "Fresh" 671 designed in 1938, I would pull them in pieces and repower with a 6BT. The detroit weighs 2800, the 6BT 1200, the detroit is a 2 stroke the 6BT a 4 stroke, etc, etc.

Am I missing something here???

05-17-2010, 11:16 AM
If it's in your boat, you need to consider trim and balance.

05-17-2010, 03:25 PM
It took me about 10 hours. A little more for painting. Your discription about rebuild is right on. As far as doing a swap it really depends what engine you like better. Both will get the job done, and both have advantages. Detroits leak like a sive, but run forever, and no injection pump to worry about. Also with liners rebuilds can be done many times. Sound is great if it is muffled enough to listen to all day.

Cummins is certainly a nice engine, have one in my truck, would not want a 6-71 in there. Too heavy, and not as smooth. It would be difficult to keep noise down in a truck just too limited of a space to do much.

In a boat think I would favor the 6-71. The boat will easily absorb vibration, and with a wet exhaust or big muffler noise should not be a problem. Really think the 6-71 will last longer, has a well proven track record.

You are really comparing a medium duty engine to a heavy duty engine.

05-17-2010, 03:44 PM
Mine are low deck 671 hn9's the old school of old school, the liners are "Buckshot" liners, so old that few have ever seen them, they have two rows of small, maybe 3/8" holes, later they went to "Figure 8" where the holes were on top one another and joined, then to the vertical rounded rectangles, then to larger rectangles. Mine date the engine to the late 1930's with only 17:1 compression. These motors had suck low compression that they almost all came with ether injectors to get them started!

I love the antiquity and simplicity but there is no way I would spend 15K each to have them rebuilt. The only thing that concerns me is once I tear it down I am committed and if I pull the liners and find that the bores are not round, the engines have to come out to be bored, at that point I can not see puting them back in....

Here is a similar engine with no exhaust


05-18-2010, 04:42 AM
Do you know if parts for your engine are available? i.e. will the newer liners fit? if not are the old style still available? My oldest is 1942 and it does use the rectangular ports.

If paying to have rebuilt and not doing it yourself, then of course cost becomes a factor. Lay out the total cost, of both ways, rebuild, or cummins swap.

Is it a twin engine set up that needs a left and right turning engine? Is the cummins available in a left? I think so, but would check first, maybe you already have.

As someone else mentioned you may have to ballest to keep trim.

05-18-2010, 08:52 AM
Looking into parts now. I tseems that almost any aprt from a 2003 6-71 will fit in the 1938 6-71. Low blocks used a head gasket, high blocks used individual sealing rings on each cylinder (like VW and Porsche) but it appears that liners are available with the newer larger ports but all have chrome rings and I can not seem to find cast rings - still looking. These old dogs have chain driven oil pumps and the chains are difficult to find but they can be updated to gear drive but you have to remove and machine the front case :(.

Old 671 natural (non-turbo) low deck, 2 valve engines only had an output around of less than 250hp @ 2300 rpm and that is part of why they live so damn long, slow and heavy, overbuilt with a hp/displacement ration of about 1:1.

That said they are antiques in every sense of the word. Parts are getting hard to find, they are being sent to the scrappers in bucketloads. The Lady Washington (http://ladywashington.org/), the 112ft square-rigged ship used in "Pirates of the Caribbean" was fitted with a 6-71 a little newer than mine, it is no longer allowed (http://seattletimes.nwsource.com/html/movies/2010021075_ladywashington08m.html)in California waters because of it!


While I do not think a pair of 6BT's would last nearly as long, they are much smaller and you can still get parts for them. I would need to take some measurments and see what gears are available to be sure that they could be made to line up with the shafts without putting the oil pan through the bottom of the boat. If they would line up then it would be a simple swap.

You date yourself with both your knowelge of 6-71's and your statement about needing a counter rotating engine, these days both engines are normal rotation and the gears reverse the STBD engines output.

Just to add to the fun, she is set up with Westinghouse Air shifters!

Here is a peak of the engine room


I have found rebuilt 6-71 naturals in the $5k to $8K range in TX and FL in droves, of course you don't know what parts were used in the rebuild but they are still available everywhere. Modern engines would be nice but these could be rebuilt in Port-au-Prince using old car parts and a hand forge....

05-18-2010, 03:36 PM
I'm not to old(46), but our primary business is building steamboats, and the engines for them. We run direct drive, no trans, as steam engines can reverse. Look at www.rappahannockboatworks.com to see what we build.

My hobby is railroads, and we have a number of old detroits in track maintenance equipment and one of the locos. Had a 3-53 in my 47 Dodge, will likely put it back in one day.

05-18-2010, 04:36 PM
30 yrs ago I worked in a boat yard and they had a couple of surplus navy launches with 671's in them and I still remember the sound and power. Not high speed but they could tow anything. If these are the original engines and if you could save them with out sacrificing $$$$$ and dependability it would make that special yacht even more unique.

05-18-2010, 08:19 PM
I'm not to old(46), but our primary business is building steamboats, and the engines for them. We run direct drive, no trans, as steam engines can reverse. Look at www.rappahannockboatworks.com to see what we build.

My hobby is railroads, and we have a number of old detroits in track maintenance equipment and one of the locos. Had a 3-53 in my 47 Dodge, will likely put it back in one day.

:cool: What beautiful boats you make. ;)
Ken Gardner

05-18-2010, 10:36 PM
Beautiful work. If the Rosebud is in Seattle then I worked on her last year when her water pump siezed at a dock. Steam is fascinating and the idea of running on fuel readily available onshore is interesting. I have 3 working model steam engines from the 50's, one powers a Buddhist prayer wheel, as well as a Sterling engine model.

There is no reason you can not run a steam boiler on WVO and i have been working with a large plant hat is running its boilers on VO for 2 months.

When I was a boy an old man down the road had a dodge Korean vintage ambulance he drove across Africa with a cellousic Ethanol Gassifier for fuel, interesting project.

I am trying to save the 6-71's in my boat but it is a battle, so many parts are obsolite and I have taken to calling all the shops I can find and collecting spares. The forecastle had been crews quarters and I have made it into a tool room with a press, drill press, work bench, vice, etc and have been collecting water pumps, fuel pumps, fittings, hoses, ect to have on hand. I could only be more interested in these antiques if they were steam powered. What a joy it would be to stoke a fire to pressure and go.

05-18-2010, 11:34 PM
Long ago the military liked 6-71's, they even used twin 6-71's mated to a common gearbox driving a single propellar. I believe I have heard of turbo'd 6-71's making about 400 HP.

05-19-2010, 07:14 AM
The military loved them, the same block can be turned end for end, be made counter rotating, the exhaust and intake sides swapped and the parts from a 2000 6-71 could mostly be used on a 1938. But as we all know the military has a different set of rules and does things differently. They were committed to the 6-71 even though it was very difficult to start below 40F and had ether injection or aux air intake heaters that were diesel fired, it was the modular part they liked. You could put new liners in the block and it was new, you could canabalize motors and build new ones in the field, etc. They could be bolted together to have as many as 4 6-71's driving a single shaft (it was difficult to make an in-line diesel motor of more than 6 cylinders for some time).

Johnson Towers did a 6-71 Turbo that puts out 485 hp and the 300's were quite common.

05-19-2010, 04:27 PM
Redbud is here on the east coast.

Have not tryed wvo, but have set up a burner for Bio diesel for a boat in Ca. Our own boat is wood fired. Saving the veggie for the car and truck.

Good luck with the 6-71's

05-19-2010, 07:03 PM
Checked today and the boat I worked on was built by the Elliot Bay Steam launch Co.

Had an hour today to play with the STBD 6-71, I am on the fence as to wheather it is simply glazed from being idled more than run for 10 years or if it is in fact just tired. Located FP in-frame rebuild kits for $1100 but found that I will need to lift each motor at least 8" to get the pans off, to get to the rod bolts, to remove the piston, liner and rod sets. This means that I will have to get someone to realign the engines to the shafts after the rebuild.

Looked through some of the old manuals I have collected and the operators manual states that the low block, 6-71 2 valve engines needed either or intake air heaters to start at all below 40F. I imagine that installing turbo pistons and bumping the compression from 17:1 to 18:1 will improve that a tad bit but I fear that they will always be difficult to start. Perhaps routing the boiler that supplys heat to the radiators in the cabins, through the engines would allow me to preheat without firing the genset but it would still take some time so perhaps ether injectors are the best option.

Whatever the answer is I am going to need to lift the 2800lb lump at least 8" off the stringers just to get the pan off unless I am missing something.

05-20-2010, 04:27 AM
Check again on the compression of the turbo pistons, as they are normally less then non turbo pistons. We use ether injection for cold starting. Engine block heater will do well also. However most of our stuff is too far from power.

to line up the prop shaft after lowering the engine use a feeler gauge between the engine flange and the prop shaft flange. Do this in several places and line up to within about .001 and you will be fine.

05-20-2010, 05:50 AM
Hi, since you asked for random opinions, I will throw in mine. Nostalgia has its place, but an old design with a challenging parts supply chain is a headache.

Imagine some scenarios:
a) You go on a trip, need a part - and spend your limited vacation time chasing down a part. In my house, that would be PO'd wife.
b) You decide to sell this boat and the potential buyers want something that can be reasonably maintained by "normal" engine people.
c) The engines need a part replaced, but you can't find it, so you decide to go on the trip anyway. The part fails at sea, there is a storm, and with no power, your family is at the mercy of the waves. In your case, you can probably work through it, but the next owner would probably be SOL.

Perhaps less important, but those old 2 cycle engines can dump a lot of oil out of the exhaust. That oil goes right into that nice pristine water you are trying to enjoy.

If you want a heavy duty marine engine, there are always these guys:


They make / rebuild MAN engines under an agreement for certain sizes. I visited the MAN factory last year - pretty impressive how much power and efficiency these newer engines have. You might achieve double the fuel efficiency of that older engine.

05-20-2010, 07:52 AM
Chris, Some months ago you posted this:

"I have gone to great lengths to keep her period while hiding modern gear, as an example I hit a modern stereo behind the faceplates of 1940's Helicrafters shortwave radio gear, used vintage gauges to reflect the state of modern inverters and battery banks and hid LED lights in period fixtures. She appeaers to be period but is completely modern internally except the engines which are period but rebuilt 2 stroke diesels fitted with state of the art VO systems."

Now you are looking at doing something with the engines. If you like the 6-71's get a newer vintage so that you have some assurance parts availability for the foreseeable future. It sounds like you want a boat that can be used and enjoyed. A good Cummins or Cat can be just as reliable if the 6-71's don't work out. Your talking about the heart of the beast.

I was once involved in doing an inframe on a 16-71. The rebuild, if you have room it is not hard to do. One of my guys spend a lot of time laying underneath the engine.

For easy starts we used a jacket water heater to keep the engine warm.

Just my 2 cents...

05-22-2010, 10:38 AM
OK, I went to a friends shop, the entrance is either through a small door facing on some railroad tracks or through the back door which is under a flight of stairs in the parking area of a marina pier. Filthy shop, crap all over the floor, old titty girl photos on the walls under layers of exhaust dust and receipts from 1962, phone numbers scrawled on the walls at odd angles like Main-3482 and East-2246, benches covered in oily tools, rags, parts, drill bits, an occasional pistol or half eaten sandwich, dust and grease everywhere, tool boxes with all the drawers open and completely unorganized, all lit with a couple of flickering florescent fixtures hung from the beams on coat hangers. Drill press with exposed belt drive, Bridgeport mill that came off a navy ship, lathe with exposed gears buried in corkscrews of various non-ferrous metals, bits and pieces of engines hanging from nails, piled in corners, stuffed in nooks and crannies in the walls, like a dark filthy buthershop for machines.

My old friend went into the Navy at 17 and spent his tour rebuilding 671's. Today he is shorter than he was then, at least twice as wide, has a full white beard except for the yellow nicotine stains under his nostrils and white hair pulled back in a pony tail except the left side which is combed over the top. He struggled to get up from his old office chair with one leg hose clamped together at a split in the wood, fighting a combination of ruptured discs and the extra 80 lbs he carries, his dirty denim coveralls almost burst the zipper when he sits. In one hand was a worn plastic pouch of rolling tobacco he is constantly filling from a bag under his desk and in the other was a coffee cup with permanent stains around the base of the handle and the inside, the outside had brightly colored letters spelling LOVE across the front.

I asked how he was and he gave his standard reply "I could bitch" and began ranting about people I have never me, their relations to one another and ancient stories of the terrible things they did or had done to them while he motioned with the cup toward the doorway to the hall which contains an ancient Atwood typewriter, stacks of papers and manuals weighted down with lead ingots for making bullets and pistons turned upside down and filled with cigarette butts, below the calendar from a diesel filter company that went out of business before I was born is an ivory Mr. Coffee with brown accents, I am sure it was once white but I have to think of everything in the shop as "Sepia tone" or leave. Mr. Coffee is nestled with the powered creamer, a spoon with dried something on it and assorted mugs turned upside down on an old stained paper towel. Choosing a cup is like the shell game where you turn the cup over not sure if it will be clean or if something will run from under it and scamper up your sleeve. The coffee is a mixture of whatever was cheapest, the bon-ami hand cleaner he uses to wash the pot annually in the bathroom sink and used motor oil that pervades everything through osmosis.

He tells me that John Smith has done it to him again, as though I should know who John is, how he is, and their mutual history as he leads me around the bench, stepping over the half disassembled gear cases littered around like broken machine eggs, past the bubbling tank of water and laundry detergent with a cylinder head poking out one side and a rounded forms of sand cast bronze pump housings bobbing through the surface on the other and points to the back of the shop “That rat bastard dumped that shiterie here last night, says he needs two running 671’s made out of these three before he leaves for Alaska. That one’s so full of rust it must have been used as ballast and I don’t know about these other two, who knows. I rebuilt this one back in 81 and he probably found that one in some floating whorehouse, it looks older than Moses… but not as old as those antiques you have”

An hour later I was filthy and had managed to get 3 of the 6 pistons and liners out of the block, cut my index finger, had enough grease under my nails to recycle and more on my forehead and chin. The 6-71 is a very simple engine, the exhaust manifold is attached to the head but the blower (a roots supercharger) is bolted to the side of the block. Once the exhaust manifold is off, the head comes right off, well as easily as anything that is nearly 5 feet long and weighs 180lbs comes off. The oil pan is removed, assuming there is room, and you reach under and break the rod cap nuts loose and remove the rod cap. I was not allowed to look under when doing this since I would have to do this blind by feel on my boat assuming I could lift the engines far enough to get “That %$#@-sucker pan off”. With the rod cap removed a brass drift is laid on the piston with one end barely sticking into one of the air holes in the cylinder liner, a broken wooden handled flat blade screwdriver is inserted in a hole in the bell housing and the engine turned over with the teeth on the flywheel slowly. The piston jams the brass drift and slowly the piston and liner begin to lift from the block. When the whole filthy mess is at TDC you put the hickory handle of a brass hammer "has to be hickory, if its not hickory it junk and I won’t have it in my shop" is laid on the block and a prybar is inserted into an air hole and levered off the hammer handle prying the liner piston and rod free of the block.

When all the liners are out you take a rag, or an old tee shirt in this case, and wipe out the cylinder bore looking for any pitting or rust and check it to make sure it is still round. In an old medical cabinet on the wall are a series of cardboard boxes smeared in greasy hand prints to the uniform gray-brown of everything else. Each contains a 6-71 cylinder liner, standard 1, standard 2, standard 3 and so on. Each liner is fit in series into the bores with a long .003 feeler gauge. You want the liner that will not go in with the gauge after the one that will. Once you know the liner size you scrawl it down with a pencil only an inch and a half long, eraser chewed off and you can sharpen it on the bench grinder if need be, write it on a fuel filter box top from the pile of boxes in the corner next to the mound of cat litter and boat chain.

Now you check each piston for fit and each and every ring. “If you are building a Detroit and you didn’t have a file in your vice, Steve Hennesy the shop foreman would fire you right now, and I mean get out!. You measure those rings in the bore and you want 12, not 9, if you have 9 the rings will expand when she gets hot and they’ll seize right there on the dyno, that’s where your breaking them in or breaking them apart!. So you take that ring and hold the ends on that file and pull it toward you” He demonstrated opening an imaginary ring, closing it on an imaginary file in an imaginary vise and pulling it several times.

Once you have all your rings set you press a new bearing into the rod, put it on the piston, put the ringed piston in the oiled liner and check everything again. The piston comes out of the liner and goes into the block and you measure the distance from the top of the liner to the deck of the block, each liner is then lifted enough to get a shim under its upper lip “Don’t take it all the way out boy, you’re dumber than cast iron” he took out a pair of hair cutting scissors from a drawer that had no cabinet piled among the Bridgeport bits on an old office desk “you cut the shim like this ,here, and you just feed it around the cylinder like this. Then you check it again and when you have it right, check it again before I check it”. When all is well in the world and “those damn (fill in the blank)’s stop screwing with everyone’s (fill in the blank) well be a lot better off” you wipe everything down with the old tee-shirt, again assemble the pistons in the cylinders, each marked and the shims laid next to it, install the rod bearing and install each piston, liner and rod as a unit and again check the height of the liner in the block. The rod cap and other half of the bearing go on and “You button this up, test it and it shits or it ships”.

I went home looking like a minstrel and took a shower and though about it. My choices are to rebuild what I have or repower. If I repower I have to find a suitable engine, that will mate to a suitable gear and that will fit in the hull and line up with the shaft. I might be able to do that with the 5.9 but it would need water cooled exhaust, custom mounts, heat exchanger, belt driven raw water pump, marine cam and a suitable gear and gears can run in the thousands, even then I may need to change wheels to get to hull speed before redline and still cruise in the power band. Diesels in boats are like truck motors pulling a load up hill all the time, if you have too small an engine it melts, too large and it does not work hard enough to seal the rings and get hot. 5.9’s would have the power for a displacement hull.

If on the other hand I can manage to get my engines lifted enough to get the pans off by porta-powering them up one corner at a time and jamming dunnage between the mounts and the stringers, and I replace the old style liners with new style N-liners (larger air holes) and put in Turbo Trunk pistons, I will have rebuilt engines and the turbo pistons will bump the compression enough that they will start cold and not smoke. Other than the chain driven oil pump all the other parts are readily available as new pasts will work in the old dinosaurs and the front cover can be modified to use the new style oil pump.

Rebuild kits can be had for about $1500 and once rebuilt will run longer than I will be alive. They will not burn as clean or efficiently as modern engines but it is what I can afford and they will suit the vessel and its intended use well collecting a few hundred hours use a year – Unless the economy gets worse and I have to move to the Sea-of-Cortez in which case I would have to sell and build a motor-sailor trimaran. What a good time that would be, warm weather, warm clear water, great fishing…..

Displacement hulls are interesting, they have a theoretical maximum hull speed determined by a formula: Theoretical Hull Speed= 1.34 x sq. root of waterline.
For a 25ft waterline...1.34x5=6.7 knots THS. In my case the sq. root of 52 is 7.21x1.34=9.66. The theory of hull speed has to do with the 1.34 multiplier, since a displacement hull travels through not on top of the water it creates two waves, one at the bow being pushed by the boat and one at the stern where water can come up. Physics states that the speed of a series of waves equals 1.34 times the sq. root of their wavelength, which is the distance in feet between the crests of the waves.

As the boat speed increases the bow and stern waves get larger and when the wavelength becomes equal to the length of the boat, the hull has dug itself a hole in the water and the bow and the aft are sitting on their respective waves rolling along the surface of the sea. Going any faster will require more and more power as increasing speed increases the wavelength, the aft wave (quarter wave) moves aft and the aft of the boat falls into the hole as the bow tries to climb up the hill of the larger bow wave. This is only a guide as other factors come into play, the hull is rounded so the actual waterline is longer than the length of the boat at the water, the shape of the hull increases waterline as speed increases and the boat is sucked into the water particularly if the hull has overhangs fore and aft, and the aft can have increased flotation (wider and steep to prevent the aft from falling into the water) and be designed to suppress the aft wave.

This is why you see racing sail boats with long bows and wide flat sterns that almost appear pregnant in their beam. These displacement hulls can actually plane and seriously exceed hull speed. In my case with 52’ at the water and 28 tons of displacement I actually have a hull speed of about 14knts with a maximum of about 18knts. To change to MPH you multiply by 1.15, so my vessel runs out at 16.1 mph and maxes at 20.7 and only takes about 300HP to achieve this (two hp per ton of displacement). Other factors come into play like wave drag and weight which is why trimarans can be expected to achieve 1.6 time hull speed and move faster than the wind while racing designs can exceed twice hull speed. They don’t need ballast since they are wide and the hulls are very long and thin to reduce drag, being light and thin they produce small bow and quarter waves thereby increasing theoretical hull speed.

All that said, it looks like I am going to rebuild what I have and not having loads of time or money my project timeline just extended until next summer before I can take her out.

05-23-2010, 06:32 PM
OK, I went to a friends shop, the entrance is either through a small door facing on some railroad tracks or through the back door which is under a flight of stairs in the parking area of a marina pier....

I always dig steps through the looking glass when they happen.

Bus Boy
05-24-2010, 07:33 PM
Chris, You Lucky Bugger!

I would love to have a friend like yours! What an hilariously vivid write up. Well done, Sir! Very entertaining, and yes I'm saving it for future 6-71 rebuild information. These venerable power plants are truly becoming dinosaurs - and those that work on them (and really know how) are becoming dinosaurs as well, I fear.

I am genuinely pleased that you apparently have opted to stay with the old 6-71s. Nothing sounds as cool, is as simple and proven a design. As the gentleman (whose article you posted some time ago) stated in his comparison of available engines for yachts, including 2-stroke vs. 4, these engines are still considered a viable, worthy choice in many circumstances. And the 6-71s, when kept under 400 hp will last a good, long time in marine applications, so he says.

Best of luck with the freshening of your motors. Sounds like you definately have a pretty fair idea of what is necessary and what is best, in regards to making your old 6-71s work for you.

Bus Boy

05-24-2010, 08:58 PM
You should learn how to twang a guitar. the way you wrote that sounds exactly like a Jimmy Buffet song... You could make millions!

05-25-2010, 01:06 PM
The fact that the 1950's 6-71's are still running with almost no compression is a statement to thier longevity and simplicity. Currently no commercial vehicles are allowed to run 6-71's in California and if you remove them you may not put them back into the vessel...

05-25-2010, 02:11 PM
The fact that the 1950's 6-71's are still running with almost no compression is a statement to thier longevity and simplicity. Currently no commercial vehicles are allowed to run 6-71's in California and if you remove them you may not put them back into the vessel...
Yet another reason we'd all be better off if California just broke off after the next earthquake and sunk beneath the ocean...

06-02-2010, 06:27 AM

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I am not sure if these are viable replacement motors but I thought that I would pass them along.

06-02-2010, 12:53 PM
I am just curious about range on your boat. Regardless of the "coolness" factor of having it original, fueling a boat can be dang expensive. Of course VO use helps control this, but it is still an effort and expense to obtain and clean up WVO.

I can't help but imagine that a more modern engine will give you 50% more range than the 6-71s. Is that a misconception or just not that important?

06-03-2010, 09:35 AM
There are issues with more modern and fuel efficient engines. In a boat the engine is bolted to the gear (forward and reverse and ratio) the gear is bolted to the shaft that drives the prop. Everything must be in line and this is accomplished by adjusting the placement of the engine. If you change engines you need to change gears so that they can bolt up, change the mounts, the coupling and possibly the props as well. This gets very expensive, then you need a marinized engine with water cooled manifolds, raw water pump, heat exchanger, marine cams, etc. So I can’t just buy a couple of 5.9 Cummins and drop them in.

I can get complete rebuild kits for the 6-71’s for around $1500 an engine and rebuild them in place or I can drop $2000 an engine plus rebuilding, marinizing, gears at $10K, mounts and possibly props.

As for original, the original engines were Chrysler Royal M48 flathead 8’s so the engines are not original, they are however period correct, which does not really matter. The real point is that they are already installed with matching gears.

Lets say a 6-71 burns a gallon a mile and a 5.9 a gallon every half mile (which is not true, see below). 200 miles a year would equate to 400 gallons on what I have or 200 gallons on what I do not have. At $3.00 a gallon that is a savings of $600 a year so just in parts the repayment is 43 years and in all honesty I will not be here in 43 years and if I am the boat will not be.

Range. This depends on several factors and is a difficult calculation, as stated above boats have a hull speed, exceeding this causes the energy required to increase steeply so lets look at travelling at hull speed. The twin 6-71’s will burn around 1.5 to 2 gph at 800 rpm 2.5 gph each at 1000 rpm, nearly double that at 1200 rpm. She does about 7.5 knts at 800 rpm. I do not know what the fuel consumption of twin 6bt’s would be but for a displacement hull 1 mpg is pretty common.

06-03-2010, 09:56 AM
I think the practical approach is to rebuild what you have as long as you can. When they are beyond repair, investigate the replacement options. Considering that rebuilding is done in place - there's probably much less down time involved, less cost, less hassle... Even if the efficiency is lower on a 2 stroke, I'm sure you can find SOME way to set the boat up on WVO.

The Cummins conversion might be great - but only if you have too much money burning a hole in your wallet and the desire to chew up a lot of time and effort to make it happen. I know I never have enough money and time - especially all at the same moment.

06-03-2010, 09:57 AM
Pop owns a marina on Lake Ontario. Guys there will easily spend a few hundred on gas in a day on the lake fishing for salmon. The summer will tell how many are game for that madness this year,.but then the upper 10% of the income distribution have done better these past years than the lower 90.

I think there's only 2 displacement boats in the marina, and 1 has sails.

06-03-2010, 10:11 AM
but then the upper 10% of the income distribution have done better these past years than the lower 90.
Government workers on all levels, union retirees and the politicians have done pretty well recently - but they are probably the ones in that upper 10%.

06-04-2010, 08:14 AM
I already have the VO system built and have converted 6-71's in the past so she will run on VO. As for down time ROTFLMAO, I will be lucky if my daughter sees this project done! If I was a rich man I would not have gotten a restoration project... Well I probably would have but I would have been able to pay to have a lot of things done. First thing i did was have her pulled where i replaced 64sqft of steel below the waterline and removed the teak from both side decks and replaced the steel under. Back in the water and I built a tent over her and removed the entire foredeck, cut out all the rotted steel and replaced it with new and am now replacing the teak deck which I managed to save.


The house is true 1 1/4" Burmese Teak as is the wheelhouse, I stripped every inch of both with a heat gun and a scraper, sanded every crevice, bleached and cleaned with oxalic acid, sanded until I had not finger prints then laid 18 coats of varnish on sanding every two coats. The house roof is Larch tongue in groove over teak beams, covered in felt and canvas then doped and painted many times in 60 years, had to be sanded, sections had to be cut out and filled with epoxy, faired completely and painted with primer and 4 coats of modern paint. This was both the house and wheelhouse roofs.

At some point some idiot had taken the back of the wheel house, boxed it in and installed sliding windows. I removed these and cut the back of the wheelhouse back to the original shape, made teak supports to match and had new glass cut to match the original build drawings. Then discovered that the 15" of curved, shaped molding around each window had to be hand made. That was a week of evenings with a band saw and a sander chucked up in a drill press. I think I still have no fingerprints on one hand.

The master stateroom had two single beds, I gutted it and installed one queen bed and a couch but the hardest part was replacing the ceiling which someone had covered with acoustic tile. Individual panels had to be made, Hatteras White vinyl glued to each one, attached to the ceiling and teak battens made to fit the seams, center and edges. Not one met at a 90 and all but two were compound bevels.

The winch alone took nearly a year. The company who made it went out of business in the 70’s, I had to lathe many of the parts myself and learn to repair cast iron. Once the body was finished I had to adapt a modern motor and build a case around it so that the original castings could be used.





The Salon windows originally rolled up and down but had been sealed and varnished shut decades ago. I tried to restore the crank mechanism but it was pointless. Eventually I modified a set of power window regulators, found window felt and modified it to work and installed the windows as power windows.

Now I just have to finish the foredeck, finish rewiring the entire boat, rebuild the engines and… Something else will come up. I have done all this evenings, Saturdays and lunch hours for two years.


This is the foredeck teak going back down onto fresh steel. Each plank must be individually bedded, spaced and weighted in place while the bedding sets up for 4 days.

I am going to rebuild what I have, the fuel savings would pay for modern engines were this a commercial vessel heading to Alaska 4 times a year and running 24/7 but over the 200 hours I will use her a year it would take forever and be very expensive. That said I am looking for a pair of 5.9’s to slowly prepare in the back corner of the garage. I can not afford to have someone charge me $15K per engine for an in-frame rebuild and having my skill set, if I could I would not. I figure a day per engine and maybe $2K

06-04-2010, 01:25 PM
All I can say is that I am impressed.

06-06-2010, 11:09 AM
I had several loose planks on the foredeck, I though they simply needed refastening, I though this becasue the surveyor I paid a grand to told me so. I started cleaning under the loose end and as I applied upward force by hand I could see a large section of the deck move. I cut the caulk with a razor knife and pulled and up popped a section 3 feet wide at the base. What i found under it was nothing but rust scale.


After removing all the rust and cutting away the tissue paper of rust, I found that the cross beams were perfect and rust free.



The steel was then patterened and cut and stitch welded in place.


Here is the teak laid out last spring. Every plank had to have the caulk removed from both sides and the bottom was covered in bits of rusty deck, rotted fasteners, Irish Felt (wool soaked in cole tar) and tar which was the bedding compound in 1952. This took weeks with a scraper and a propane torch followed by 3 sets of planer blades.


Of course by the time it was going back on the deck many of the planks had tried to return to thier original shape, so as each course of 4 planks is bedded it must be forced into shape by welding small tabs to the deck and driving wedges in with spacers between the planks. Not a lot of fun as you are doing this while the adhesive is kicking, on your knees on steel, covered with adhesive, then you get to weigh the whole mess down!

06-06-2010, 05:11 PM
Very impressive. With you writing skills this could make a good how to book on refurbishing a yacht . A friend is doing a vintage travel trailer and his sister is going to film a documentary that they will try and sell to one of the cable channels.

06-07-2010, 08:34 AM
I can wire her, weld and fit, plumbing, engines and trans, paint and finish, still the issue is time and money, mostly time since I do not ahve the money or inclination to pay others to do crap work.

I had an electrician come in, he quoted me two guys @ $65 hr ea for a week to rewire the main salon, then based on that they would quote the rest of the job. I sat there and counted 3 light switches, two overhead lights and two 120vac outlets in addition to leads running to the Nav lights on the cabin sides. It took me 1 hour to remove all the wiring and 1 1/2 hrs to rewire it with new 12/2 and 14/2 tinned marine cable. I called the electrician back and had him come by, I showed him the work and explained that somehow I had done in 2 1/2 hours what he wanted me to have done in 80 hrs at a cost of $5200. He asked if I was looking for work.

One of the welders I hired was an out of work ship yard worker, terrible field, most of the yard welders learned in trade school or prison, they get poorly paid, work in terrible conditions and develop poor skills and bad habits when working, then get laid off without notice as one stage of the project is completed. Well it took him 2 weeks to get 2 sections of steel 13' wide and 32" deep laid and welded, at one point I found that he had cut 1/4" off an edge 13' long using an entire box of cutting wheels and 4 hours of time. The box of wheels was sitting on top of the PLASMA CUTTER! I found this the day I returned from a 2 week trip, I started at 4pm and finished the remaining 13' x 32" before 8pm and fired him the next morning. I hired 3 painters to paint the master stateroom, not one lasted a day, they worked like bored children. Finally I called a Bosnian house painter, he quoted me $500 for a bathroom in a house, prepped and sprayed with enamel. I met his a block form the boat and told him that i had lied, that the room was the size of a bathroom but was actually on a boat and that if this made the cost go up he could bugger off now. He looked at it and added $100 becasue of the amount of varnished wood he would have to avoid and swore that I would be happy. Two days later he was done and I could see scratches under the paint, he redid the entire job that night and in the morning it was perfect. Perviously the cheapest quote I had was $2500.

I had people quote the varnish on the house at $30K, others at $3K and everyone had a story. You can't apply varnish unless it is between 55F and 70F, the humidity is perfect, the moon is full and the stars are aligned in the house of Rectum. All lies, every last one of them, the 30K guys were blowing so much smoke up by backside that I felt like a hot air baloon, the 3K guys were going to do a crap job and jack the price up to 7k before all was said and done. One company said it would take 2 guys 2 weeks to strip the varnish from the house before sanding and prep. I started at 9am and finished at 5pm, one guy with a heat gun and a scraper.

The entire marine industry is filled with thieves and liars. But even if you have the drive and the skill, having the time is another issue. My boat is under a blister I built by hooping PVC pipe and shrink wrapping the whole mess. This means I can work regardless of weather and often I will put the family to bed and return to work until 11pm.

Here she is at midnight shot from the front seat of my truck heading home.


Bus Boy
06-12-2010, 09:19 AM
Man, You've Got A Lot Of Nerve!!!

I nearly fainted just looking at the rusty mess you encountered... ... Sweet job on the winch by the way. Better than new!

Chris, you've restored my faith. I sometimes get discouraged looking at my ancient GM bus, and it's not really in so bad of shape. I'm a pussy compared to you!!! That is really something else. Excellent work and dedication to getting the task on hand completed. You will be as proud as a new Papa when she's usable (as in plying the high seas under her own freshly restored, WVO guzzling DD 6-71's). Hell, I'm proud of you and we've never even met!

I wonder, as in a bus conversion, is one ever really finished with a large yacht restoration? Still, it is obviously a labor of love for you, and you have accomplished much. So far, so (very) good.

Best of luck and with her. What have you Christened her? Have you considered (unless I've missed it) showing your progress on your Frybrid site, as you've done with your Neoplan bus conversion? That would be very cool, if you have the time.

Kevin (AKA Bus Boy)

06-12-2010, 10:36 AM
The circumstances dictated the project. She passed an ultrasound and survey and was dirt cheap, I thought I was getting a great boat that had some cosmetic issues. When I went to test some of the systems I had a thru hull valve feeding the toilet break off in my hand. I had to have her hauled to repair it, when they hauled her the straps broke two 16” x 16” holes in the side of the hull just below the waterline. I repaired the holes and found that they had been caused by water leaking into a space in the hull where it rotted the steel from the inside out, the leak came from deck damage. I repaired the hull and found a few other thin spots and repaired them as well as the thru hulls and put her back in the water. Great, all ready to go… Then I found the deck rot. About that time I was ready to sell her for scrap, I had not embarked on this kind of project and frankly regularly go through all 5 or the Kubler-Ross stages of grief; Denial and Isolation, Anger, Bargaining, Depression and Acceptance.

Right at that point I discovered the build plate on the helm, it is a small chromed bronze emblem reading “Feadship” and below the name is “Holland” and “No.7” I began researching and found that Feadship is considered by many to be the finest producer of Yachts in the world and have a long history of building yachts for people like Paul Allen, Henry Ford, kings and queens, etc. I contacted Feadship and they told me that this was not a Feadship and that they had no records of her, I sent them several magazine articles I had found from 1952 showing my boat and giving detailed information about her as a Feadship. The Feadship archivist contacted me and had located several photographs, build drawings and brochures featuring her. It turns out that they had built two coastal patrol boats for an Asian government and made 4 hulls, of the two remaining hulls my boat was made and another with an open bridgedeck.

Feadship had been founded in 1949 when the Dutch government told shipbuilders that they could not produce yachts, most of Europe was trying to decide how best to cook their dogs in the aftermath of WWII and the few rich did not need to be swanning about in yachts. 5 of the best yards formed an association First Export Association of Dutch Shipbuilders; FEADSHIP and began building yachts of steel when everyone else in the world was still using wood, and they marketed these yachts to the Americans who were on top of the world in 1949.

Looking into it further I found that none of the earlier vessels were still in existence, they had been sunk or neglected until scrapped, Feadship went on to build only huge super-yachts and the earliest surviving vessel I could find was from the 60’s making my boat the oldest surviving Feadship. The fact that she is a Feadship gives her a much higher value than if she were something else and the fact that she is the oldest Feadship probably doubles that value making her something worth saving. If however she had been a production vehicle, I would have sold her on to some other dreamer and gotten something else and this is my advice if you have an old bus with issues.

You can get a really nice MCI in good condition for less than $10K and you will have more than that into trying to restore an old bus, you will not be able to enjoy it or use it in the meantime. You really need to start with “good bones” or you will spend twice as much trying to save a junk heap that will likely rot away faster than you can repair it. Remember the work required to convert a bus is the same in a good solid bus as it is in a rust bucket, the difference is that when the conversion fo the good bus is done, it is done. When the conversion of the rust bucket is done, the bus falls apart around the interior you just put in. I can not strongly enough advise that you find a modern bus with a modern engine and good suspension and coachwork. Sell your bus to another dreamer and move into a new project on a canvas that is not rotted.


My boat, like all Feadships, was custom built. Mine was built for a wealthy businessman named A.J.Seamon in New Jersey and was built as a deep sea sportfisher to be used in Montauk and the Grand banks in the summer and Bimini in the Bahamas in the winter. This guy was a bit of a nut, he wanted all the scuppers to drain below the waterline as not to leave unsightly streaks on the side of the boat (a feature that has caused many of the issues) and he wanted it to be the biggest and best Sportfisher in America. He had a steel maidenhead cast with a skull and crossbones on it, had her delivered flying the Jolly Roger and christened “Brigand”. She had been renamed several times before I got her but being a “Documented vessel” the Coast Guard has all records of her since new and one of the previous owners had given her back her original name and dug the bondo out of the maidenhead restoring the skull and crossbones.




Bus Boy
06-12-2010, 06:45 PM
Brigand is a beaut, Chris. Fascinating history! I think it is wonderful that you breath new life into such an old, unique, and seemingly once-forgotten vessel.

As far as buses, yes the MCI is a well-built and worthy vehicle, and even one of their earlier models is no doubt worth more than my '60 GM 4104. Only thing (and at the risk of offending any MCI owners out there) they remind me of a "flying brick"! The GM PD 4104 is, in my humble opinion, one of the most beautiful. It has the rounded edges of an old Crown school bus. She's all aluminum, riveted monocoque design - just as an aircraft, with very little steel. No steel frame underneath. , etc.

The old DD 6-71 is in fine shape. It is an "N" with 4-valve head and Jake brake. We've used this bus regularly since having bought her over 10 years ago. Though I've never completed the interior - such as cabinets and counter tops - it has all the basic needs to camp comfortably for a week or more.

I realize that I will never recoup my investment, but I am in love with this Ol' Girl! Driving it is like therapy for me. I'll bet you understand. People seem to love it too. Well, they either stand there gawking with their mouths hanging open as if we'd just flown in from another planet, or they grin ear to ear and give us the thumbs up. That is, usually, anyway. When I'm accelerating (that's actually a contradiction) away from a stoplight with a line of impatient drivers behind me, they tend to extend another finger, if you know what I'm saying.

Ah well, we always get there eventually. We can cruise at 65 with no sweat. I've never been stuck (knock on wood) in the desert when we go off-roading each year here in the Mojave, though I am obviously very careful. My wife and I are heading for the coast next month to celebrate our 20th. Camping on the beach in our bus beats a hotel any day, we think.

I wish I knew what the Hell I was doing with a computer, I'd send you a picture. She's in really nice shape, overall. What I was talking about was mainly the somewhat daunting (as I have no carpentry experience) task of crafting a handsome interior. Nothing too fancy, mind you. This bus earns its living and does get pretty full of sand whether from the desert in winter, or the beach in summer months. It must be a practical, functional design that will hold up to wear and tear. That's the plan. Wish me luck!

Your yacht is going to be truly magnificent! I enjoy boating as well, but prefer to sail. Started on an 18' Solcat catamaran about twenty-five years ago. Still own a pair of Sunfish, which for me, truly define the essence of sailing pleasure. Bought a water-ballasted 26' MacGregor (the poor man's yacht!) about 10 years ago and sailed her to the Channel Islands just off the coast of Ventura, California. That was a blast, but also pretty damned nervy considering my lack of experience on open water. Wouldn't try it again without someone aboard who knows what the Hell they're doing on the ocean. Alas, the 26 footer has been sitting on her trailer here at the house since '99. Sailing isn't for everyone, and my wife has never been more than a reluctant sailer at best, bless her heart.

Please keep us all posted on your progress with Brigand, and I really do appreciate your advice against restoring a relic of a bus, and the wisdom of, instead, starting with a more modern platform, but just can't do it. I fell in love with this one the moment I rounded the corner and saw her for the first time. Yeah, love at first sight and all. An oldie but goodie!


06-13-2010, 10:42 AM
GM PD4104

The 4104 always remonded me of something Howard Hughes would have converted, lots of chrome and atomic pattern lenolium in organic shapes, full wet bar, etc.



My first bus was a 1972 GM 5307 "Fish bowl"


I picked it up in LA for $2K and drove it to San Filipe, Mexico. I pulled out all but two sets of seats and sold them to a guy who made VW based dune cars for all the old retired gringos. On my way I stopped in Calexico and paid $500 for the entire interior from a motor home that had been wrecked, I pulled every part I could, pumps, tanks, lights, everything. I installed the interior more or less and had a queen bed in the very back, then a desk on one side and storage racks on the other, then the rear door opposite the toilet and shower (boat style) then a dining area opposite the kitchen counter, then a seating area forward. I built racks on the roof to hold 8 full size sea kayaks, six doubles and two singles. I put a bike rack on the front with two mountain bikes on it and headed south. I turned around when I got to Nicaragua and came back to 700 miles from where I started and settled in La Paz, Baja California Sur and opened an adventure travel company.

She had a 6V71 and an auto box, no fuel gauge because she had been a city bus and would do 65mph on level ground and hung with the overloaded semi trucks on the hills. I made it a point to plan my trips so I could camp for the night near the bottom of any grade so I could get up at 4am when the first light broke and take the grade at the coolest part of the day, I even had a section of watering hose above the radiator connected to a 35 gallon water tank with a hose bib, when the engine temp climbed (it was often 115F ambient in the desert) I would tell my girlfriend to turn the water on and I could get about 2 hours out of a barrel of water.

I drove that thing down beaches, through tiny towns, cities, mountain passes, jungle, you name it. Great bus, great trip. A year after I settled in La Paz I drove her to San Diego and sold her for $2500.00 to some other nut who had similar plans, no idea what ever happened to her.

I understand your project and wish you the best, when you do your next rebuild why not turbo that 671 and get some more performance.

Bus Boy
06-17-2010, 06:25 PM
You are quite the adventurer! And I believe it when you say, "...I drove that thing down beaches, through tiny towns, cities, mountain passes, jungle, you name it..." These great behemoths will surprise, in terms of what type of terrain they are capable of traversing.

I once made the mistake of taking a wrong turn while visiting Jawbone Canyon OHV area near Mojave. It was a powerline road... looked like a bloody freeway from Jawbone Canyon Road. I was just going to breeze it over to Dove Spring OHV area, just a few miles away. Damned thing turned into Jeep trail within a mile or so. Narrow as Hell with no place to turn around - had a bike trailer on the back to boot.

Wound up having to bash into/plow through several severely undercut dry sandwash crossings, full throttle in first, praying to not get stuck... ...visions of a Boeing CH-47 Chinook 'copter lift-out rescue spinning through my panicked brain.

My (then) twelve year old daughter Sarah and friend Monica very nearly banged their heads on the ceiling, having bounced a foot or two off the sofa with each jolt. Yee-Haaa!!! They thought it was hilarious. I was sick to my stomach! What a nightmare!!!

We made it through though, even found a killer place to camp. My wife Kathryn had to give me six (seriously!) shots of tequila to slick my fur back. It probably didn't help that this whole misadventure began at around midnight. Next day we got to relive the entire experience in reverse, as the camp spot was pretty much the "dead end" to this cul-de-sac from Hell. At least is was light.

I rigged a windshield washer pump w/dashboard control switch for a radiator spray. Pulls off the domestic water tank. We never drink the water (always bring bottled) so didn't bother with a backflow device. Works really well if you dip into it a minute or two before you need it.

Thanks for the wishes, Chris. Very cool story with your trusty fishbowl! I'm going to ask my daughter to help me post a picture of our Baby. That's her alright in your picture! I like your interior design ideas. Ah... so much to do, so little time. :o)