150 erude prop ideas

[lastout]

howdy folks. i have a prop question for those in the know. i am running a 150 hp 1983 erude on a wellcraft 20' step vee. its a pretty heavy boat. anyway i am only getting about 4400 rpm's out of it with a 15x17 prop. the motor is running well "now" and i think a different prop would increase my rpm's. i am asking if anyone has any ideas of what size to try? thanks for any help ya'll can give.

 

[Dhadley]

Re: 150 erude prop ideas

A 17" is about what we'd expect on that boat, perhaps a 15". To get close to your target we'd have to drop 6 to 8 inches of pitch. That does not make sense. <br /><br />Lets start with your tach. Make sure its set on position 6. <br /><br />Have you tried any other props?

 

[lastout]

Re: 150 erude prop ideas

thanks dhadley, i will go out right now and check the tach. i have not yet tried any other props because it costs to get one, so i need to know where to start. thank you much for your reply and i will post again on the tach setting.

 

[Pst76]

Re: 150 erude prop ideas

Lastout, I just tried out props on my set up. 150hp with a 14 x 21 and a 14 x 19 prop. I went with the 14x19 which gave me about 5200 rpm WOT. Boat is a bit smaller 18 ft Larson deep V <br />runabout weighs about 1800lbs. The 14x21 ran me at 4800 which according to spec is a bit to low. Most seem to be speced at 5500. Don't know if this helps.

 

[lastout]

Re: 150 erude prop ideas

thanks pst, it may. i just want the best prop to start testing with. confirmed that my tach is set on 6 dhadley. any other ideas? thanks again!

 

[Dhadley]

Re: 150 erude prop ideas

OK good. Now we know the instruments are reliable.<br /><br />First lets take compression. Very important.<br /><br />Look at the linkages and make sure everything is going to the full wide open position. Without the motor running the timerbase (under the flywheel) should move til its aginst the stop screw with a rubber cap on it.<br /><br />The throttle butterflies should be flat.<br /><br />If this is OK then we need to take a timing light and confirm each cylinder is sparking at wide open. Its best to run the motor for this test with the boat still on the trailer but far enough in the water to get cooling water.

 

[lastout]

Re: 150 erude prop ideas

i have compression of approx. 95 on all cylinders. #1 cylinder is a little lower than the rest at about 90. carbs were recently cleaned and butterflies are open and flat. timer base appeares to be moving all the way. i have just replaced the coils, plugs, plug wires, and rebuilt the 2 fuel pumps. i have not checked the timing. when i do this, if it is off, can i adjust it? also, do i have to put the boat in the water or can i use the muffs? the engine appears to be running fine, but that doesn't mean its running perfevt!

 

[Dhadley]

Re: 150 erude prop ideas

Good. Yes, the timing should be checked under a load.

 

[lastout]

Re: 150 erude prop ideas

under a load, so leave the boat on the trailer and accellerate in gear on the trailer? i can do that, i'll get a timing light tomorrow, and i'll try to pick up a manual for this engine. any idea what the timing is supposed to be and again...can i adjust the timing? thanks so much for all your input. should i guess that i may have an engine problem rather than a prop problem?

 

[lastout]

Re: 150 erude prop ideas

bump.... still hoping for ideas. thanks guys!

 

[Dhadley]

Re: 150 erude prop ideas

Being so far off in rpm I'm guessing we're still having issues with the motor. Or the boat has a ton (literally) of water trapped somewhere.<br /><br />Silly question so please forgive this but -- are you trimming the boat when you try for top rpms? Did it ever perform correctly?

 

[lastout]

Re: 150 erude prop ideas

good morning, dhadley. i am trimming the motor as high as i can get it. i have only owned the boat for about 2 years and to be honest, i never paid attention to its rpm's until i noticed the speed being slower. i have in the past been able to run about 36 mph with what i thought waas about 4800 rpm's. now the best i can get is 32 mph and 4300 rpm's, and thats with the repairs and replacements i have made. but the engine appears to be running smooth, i just can't tell if i'm getting all that is possible out of the engine. sorry about the long post, wanted to be thourogh. i also will try to open the floor were the fuel tank is and see if it looks wet anywhere... thanks for that idea. any others?

 

[groundpilot]

Re: 150 erude prop ideas

Im curious .... What does position 6 on the tach mean ?

 

[lastout]

Re: 150 erude prop ideas

there is a dial on the back of the tach. it should be set to the position of cylinders that your engine has.

 

[Dhadley]

Re: 150 erude prop ideas

Well, its set for the type of stator on a given engine. Evin/John V4's and 3 cylinder motors also use position 6. Others also.<br /><br />One thing we might look into is getting the rig to a dealer that has the correct test wheel. That will effecively seperate the boat and motor.<br /><br />If the motor comes up to the correct test wheel rpms (which are not necessairly the running rpms) that will tell if the problem lies in the boat or motor.<br /><br />For instance if the service manual calls for your motor to come to ***X rpms and it does, then we know the motor is OK. Then we look at the boat. trapped water, weak stringers etc.

 

[lastout]

Re: 150 erude prop ideas

ok, well i openned up the fuel tank area and can find no trapped water. this is a 1984 boat and does not appear to have much foam floatation throughout, so i don't think water is my problem. i am getting a test light and will check the timing asap. thanks all for your comments, and sorry i was mistaken about the tach dial. thanks for clearing that up dhadley. i am going to exhaust all avenues before going to the dealer or shop....trust is in short order when i go to the shop. thanks again for all input and i would love to hear any more.

 

[Boilermaker]

Re: 150 erude prop ideas

I'm still new to all this, but what about the running surface of the boat??? Is it clean??? Any growth,or imperfections??? Wouldn't that create alot of drag??? <br />ALSO>>>shouldn't his prop diameter be in the 14" range??? <br />I would think he should get much better performance out of a 150 on that boat.

 

[lastout]

Re: 150 erude prop ideas

i would definately like to get better performance. figuring how seems to be my trouble. boilermaker, my hull is clean and appears to be the way its supposed to be. i see no imperfections, gouges, or problems. thanks for your reply, every idea helps! its the ones that think to themselves "man, maybe its this....nah!" that can often times be the fix if they say it. thanks again.

 

[lastout]

Re: 150 erude prop ideas

dhadley and anyone else... i got the manual for my motor today and it says in the tune up section that with a test wheel on, my engine should be running at 4800 rpm's. my question is if this is a representation of what the engine should be turning under normal load. if it is then my reading of 4300 rpm's is not that far off and it may be a propping problem rather than an engine problem. any response to this would be greatly appreciated.

 

[Dhadley]

Re: 150 erude prop ideas

No. A test wheel rpm is a reference number since the boat will not be actually moving.