To repower or not part 2

Cleaned and rebuilt the carb. Hope the float levels are correct as all the spec info I could find talk about the round-bottom floats and mine are wedge shaped. One drawback with this very old tech. But once again pulled a significant amount of water and gunge out of the bowls, so I'm going to pull the tanks and drain the fuel lines and filter before firing it up. I don't want to refill it with crap again after all that work. For some reason, the PO never replaced the fuel filler cap O-rings, so rain water was free to leak into the tanks. I'm sure there's litres of the stuff in there. I wonder if I could use a water-separating diesel filter instead of the regular spin on gas one.

 

I think if I was going to replace the engine, I'd pop in the diesel just to see how well it works. I can always switch back, but heaven knows it'll be a lot of work.

 

The reason I suggested the mpi motor was for ease of fitting plus the excellent economy and reliability. Just popping a diesel in is a big job . You have to replace the stern gear to cope with the torque for a start. Not to mention bearers and mounts. I have been down this road before.

 

If your putting in E10 gas, all it takes is a teaspoon of water per gallon of E10 to cause a phase separation into water-ethanol on the bottom with pure gas floating on top. And the E10, the alcohol water mix is highly corrosive and also a real good tank cleaner.

All you need is to pump the tank completely dry FROM THE BOTTOM, not using the fuel pickup, then refill with small amount of gasoline like a few gallons, then rock the boat a while and pump it dry again and it should be ok. Use the pumped out gas diluted into your car tank. Modern car will have a knock sensor, so gas with lower octane as long as it is clean will run fine. I would likely run it through a fuel filter first if it is dirty.

 

If we are still talking gas V8, I didn't think fuel injection offered much benefit in terms of economy. while it's true they do offer some improvement in efficiency, fuel injection evolved due to increasing air quality standards, not efficiency requirements.

 

I'm not sure this will cut it. I have no idea if the tanks have ever been cleaned; in fact I doubt it. the frames holding them in place are held with square nuts. If that has ever been moved I doubt a shop would have reused the original archaic hardware. I suspect the interiors of iron tanks after 60 years look like the 3rd circle of hell.

 

Electronic fuel injection also was developed for improved efficiency. For auto manufacturers meeting fuel economy requirements can be more difficult than meeting emission requirements. EFI generally provides much better control of mixture and more even distribution between cylinders than possible with a carburetor.

 

True, but when fuel injection started to become universal in the late 80's it was in response to EPA regs. Only recently have we gotten serious in terms of efficiency; for decades it was about air quality - and horsepower. Case in point: my bud has a late model Ford full size pickup with diesel. With his camper on he gets about 13mpg. Until recently I owned a '73 24' Dodge motorhome with a 413 and a holly 4-barrel. I reliably got 10 mpg. Over 40 years all the improvement there was offered by the diesel engine.

 

I spoke to an old friend a while ago who removed a carbureted chev MerCruiser from bis 28 sea ray and put in a new mpi MerCruiser. He told me the increase in economy was fantastic and the turnkey starting hot or cold no choke or pumping the throttle. He cruises at 9 knots with occasional high speed runs.

 

Fantastic improvement?
MPFI certainly does run better, starts easier, just like a fuel injected car. But you dont know how worn out his other engine was, so improvement in fuel economy was dramatic from the old worn non computer controlled engine..

I did change from points to a Pertronix Ignitor and gapped plugs to 40 thousands, and it starts better and runs smoother than it did with points. Prior owner was always messing with the points, in fact when we tested it before buying he was in there cleaning and gapping them, I don't think he knew much about engines.

 

Boat builders are satan spawn. I had aplenty of room to slide a tank out a hatch but the buggers welded a long fuel inlet stack on one side so I had to cut away the deck. Grrrrr.



Also I found 3 layers of gook in the tank; something above the gas, and something below...

 

I just saw someone selling a complete propane conversion kit with 200 litre tank for 300 bucks. Has anyone converted their boats to run on propane? I did this years ago to an RV, but I've never noticed if most fuel docks carry propane...

 

He has had the boat for years and had the old motor when it was good.

 

A couple negatives,
it will use a lot of propane,
propane costs a lot more than gasoline
hard to refill a large tank.


Perhaps propane is maybe more likely to leak and explode than gasoline. it seems that way to me that when propane explodes the explosion is more massive, maybe cause it's high pressure causes any leak to be much worse than a gas leak, assuming you fuel tank does not rupture and you have antisiphon valves, gasoline is not as dangerous.

 

For what you're trying to do it seems you've got the wrong boat.

Perhaps you should sell this boat and get a full displacement boat like a Willard or Fisher.