i get 18 knots at full throttle well the boat i heard is 4550 pounds there was 4 person on board and the boat plain off at about 15 knots, what can i do to get more speed ? (mercrusier 5.7 litre 350 hp , prop 15x17).
you have a major problem somewhere. is this boat new to you? i have a 99 23foot deckboat with that weight and power. runs out at 40mph. have you checked compression, could be the hull is holding water in the foam. did you try triming the outdrive?????
When was the engine last tuned? May be running on half its cylinders? Fuel tank contaminated with water or fuel that has gone bad. Carb may be due for rebuild. Dirty hull and as was mentioned, lugging around a boat load of water soaked foam doesn't help. You have gauges! What do they indiate? Water temp, oil pressure, volts, and tach (at wide open throttle).
For one thing, you have an automotive distributor in your boat. Not sure about the carburator you have, the fuel system or anything. What was this engine when you put it in the boat? Is any of it marine?????
Since you aren't getting full speed, I would assume you aren't getting full WOT (Wide Open Throttle) rpm specified for your engine, which should be between 4600 and 4800.
Here are a list of causes to go along with the already known issues.
List of possible causes of low WOT.
Engine Won't Reach Operating RPM. Check
Fuel condition. Type and Octane possibly old fuel
Propeller pitch or diameter, damaged blades
Restricted fuel pickup tube or anti siphon valve Fuel System Test
Crankcase oil volume, high oil level can cause aerated oil and lifter collapse
Marine growth on hull and outdrive
Wrong gear ratio in outdrive
Restricted carburetor air intake (clogged flame arrestor)
Restricted exhaust system (broken exhaust shutters/flappers) in engine transom shield or drive
When was the engine last tuned? May be running on half its cylinders? Fuel tank contaminated with water or fuel that has gone bad. Carb may be due for rebuild. Dirty hull and as was mentioned, lugging around a boat load of water soaked foam doesn't help. You have gauges! What do they indiate? Water temp, oil pressure, volts, and tach (at wide open throttle).
No, that is not a marine carb, you can see the automotive bowl vent just under the flame arrestor under that little metal cover. It works well with the automotive distributor.
Wrong advance, wrong fuel, no wonder it won't run right.
Plus, it's dangerous.
It sounds like its better to buy a new engine then, it seems like this boat is a half automobile ,like some of the speed like on dry land, and i have to change all them parts ...how hard is it to bracket on 2 outboard engines ?
i have found the old carbarator getting it rebuild , do you know how to route the vacuum from off the distributor (of course i am going to get a new distributor ) but i want to know the complete Vacuum route from the carbarator to the distributor.any specs on it would be good and what psi gas pump should i use .
