Dave,

I think that small diesels would be very nice in your 29. Look for high-speed engines that have the same speed and horsepower as the stock engines. Yanmar makes some very good engines, and of course the Styr engines from Austria are the best. New diesels are expensive, used and rebuilt may be just as good.

Choose someone who installs diesels. Often the Yanmar dealer or someone who works with him will have experience installing the engines. There is no special skill in setting the engine in and lining it up with the prop shaft. All the skill is in adapting the wiring, adding diesel-type filters to the fuel system, and putting in sound insulation.

The wiring is not a big deal if you get a harness and panels with the engines. I put all the instruments into the Marinette panel to preserve the look of the boat, and added stop buttons (you can turn the ignition off and the engines don't care...) and new key switches. Most boats do not need the preheater or glow plugs or whatever cold starting aid since the engines are enclosed.

Diesels need clean fuel. You will need new Racor fuel filter$, a 30 mike filter/separator followed by a 5 mike engine filter, which often comes on the engine.

You can hire a carpenter or just a handy guy to do the sound insulation. You will need to line the entire cabin sole above the engines, and the firewall forward of the engines.

I am going to the boat over Christmas and will take some photos. I need to put a lot more information on my yet-to-be-posted website.

John I think they changed thickness in hull skin when they went to the what I call "stepped bow" below the water line. early 1970's

Dave I will take plenty of picks. for you If this goes through I think it will shear economics are driving me. You do the math 1 hr. round trip to work each day @12.6 gal. / hr. that's $35.00 / day

More troubleshooting

Lack of Power at WOT

I reconnected the black wire to my coil which sends the signal to my tach then I disconnected my Chysler ECU and the tachs worked fine and the boat ran great. It had more power and I was able to get on a plane with the engines struggling. Now that my tachs are working I do still have a problem with my starbord engine. Prior to the new distributors I couldn't get over 2200 RPM at WOT now I cant over 2800 RPM. I do have a lot more power and boat is going faster, I'm able to get around 20 MPH but before I had this problem 20 MPH wasn't even half throttle for this boat. The top speed of this boat before I installed the new distributors was around 12 MPH on a good day. I think a compression test might be my next step. Anyone have any thoughts.

i have gone through this lack of topend power thing and after reading all the posts i can find on the subject i have tried : replaced all filters, rebuilt the fuel pump, had carburetor rebuilt, then after exercising the advance springs (rusty in there) i could not find the parts for the distrutor (prestolite) so i purchased a mallory ylm549av and installed it it seems more responsive when gassing it in neutral but can not get over 2900 rpms on the water. still have the same problem. this engine does use some oil so i assume its a little tired but this thing ran fine last season. also had the props ck'd and they are now up to original specs. what the heck is next ? starts and idles easily. please help.....



Answers

1. Check to make sure all the wires are on the right plugs (which could not be the case after all the thrashing you've done).
2. I assume you retimed both motors?
3. Are the carbs getting enough gas? If the motor makes power initially, then sags badly, you have a fuel pressure problem. (I'm going through this with one of mine at the moment.)
4. Run it hard, shut it right down, then pull plugs and read the colors. Stark white indicates fuel starvation of incorrect timing; dark brown says ignition problems (wires, plugs, etc).

Jeff

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Run it hard, then shut that motor off fast as you can--do NOT let it idle. Let her cool down, then pull the plugs and read the colors. Be sure to record the cylinder # and color for that cylinder.

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STOP!!!!!!!!! The first thing to do is check the total timing at 3000 rpm. Many people time the reverse engine wrong. You should have 28-30 degrees at least.

:d/ Well guy's I did it I purchased the Cummins 6Bt. 220hp. cpl.#793 for my 1968 28' Hardtop 01-08-2011 and "now it's on". It's on the way here from Mass. by truck!!!

YES WHERE THE PROBLEM IS IS THE EXPANSION TANK BUT I CAN MOVE IT TO THE SIDE OF THE ENGINE COMPARTMENT IF I NEED TO

You can always move the engine forward so that it can be raised, and put a spacer in the driveshaft between the flanges.

Hey guy's do you think I can keep my 1 1/4" prop shaft? Also could you guy's take a look at a 72c trans. on ebay 4 me? I think it has a coupling/u-joint that could help me. The item # is 260627076752 I'm thinking it could help level out the motor therefore keeping the top front of the motor down. Thanx guy's!!! so far I'm at just under $6000.00 with purchase,tune-up,valve adjustment,gaskets,hoses,fuel lines,thermostat,belt,plus we had to move the turbo from ontop of the exh.manifold to the rear. Will keep posting!!!

Jeff is right, it's not so simple to put a U-jointed shaft in. The problem is taking up the thrust. The entire thrust generated by the propeller is pushing the shaft forward, and that thrust is normally taken up by a bearing in the transmission. In effect, the boat is pushed by the transmission and engine.

In order to use the flexible shaft, it is necessary to provide a thrust bearing. I mounted an industrial pillow block bearing on a crossmember that I added just forward of the stuffing box, and that bearing both located the front of the shaft, and absorbed the thrust. A special machined piece clamped to the front of the shaft, forward of the bearing, and provided a coupling to the driveshaft, which had a constant-speed joint at each end, and telescoped slightly in the middle. This let the engine move an inch or two in any direction, so I was able to use soft mounts of the kind used on generators. I used two rods to absorb crankshaft torque.

Before you write this off as just another aerospace engineer without enough to do, consider three things: I already had the engine, and it would not fit at an angle without raising the deck. The engine is 4-cylinder, and so could be mounted further forward to make room for the crossmember, bearing, shaft, etc. And the expensive parts, the new thrust bearing and the fancy drive shaft, were available cheap as surplus, one from an industrial junkyard and the other off of a front-wheel drive car.

I do not recommend this approach unless there is no other way to fit the engine in. The Cummins runs as smoothly as any engine anywhere (inline 6's are inherently smooth, perhaps Jeff knows why) and I don't see any advantage to it. If I had it to do over, I would buy a different motor....

Doug,

Do you still have the 100hp diesel you had in the 28. I have considered this for my 28 express. I run long trips at slow speeds but do not know if it would be worth the trouble. If you are interested in selling it please e-mail me.

John