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| Speed issue has returned https://www.smwebhead.com/phpBB3/viewtopic.php?f=11&t=1121 |
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| Author: | AlexJ [ Fri Jul 20, 2007 10:32 pm ] |
| Post subject: | Speed issue has returned |
On my 238, the 5.0 volvo sx drive only goes 31mph according to gps SOG at max rpm of 4000, at full throttle. Max wat for this engine is 4800 to 5000. The prop is a 14 1/4 x 19 from turning point propellers. Tank is full of gas, 50 gal., boat does not have any gear on board, 1/2 tank of water. Any suggestions from any motor guys?? Or anyone?? |
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| Author: | Jim_R [ Mon Jul 23, 2007 5:57 pm ] |
| Post subject: | |
Is the bottom clean? |
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| Author: | AlexJ [ Mon Jul 23, 2007 6:07 pm ] |
| Post subject: | |
Yup. I made sure of it. The prop manufacturer suggested I go back to the 17 inch pitch which I will do and try out on Lake Ontario in Two weeks. I'll be testing the boat there while on vacation for the week. Anything else I could check? |
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| Author: | jvalich [ Mon Jul 23, 2007 7:45 pm ] |
| Post subject: | |
If it's fuel injected I would check the fuel pressure. |
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| Author: | AlexJ [ Tue Jul 24, 2007 7:32 am ] |
| Post subject: | |
No fuel injection, carburator. |
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| Author: | Jim_R [ Tue Jul 24, 2007 7:39 am ] |
| Post subject: | |
Is the engine running good - no missing, hesitation, popping, and good plug color? Volvo placed a 14.5 x 19 AL prop on it stock, and published WOT speeds of 40 - 43 MPH. Still have the stock prop? |
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| Author: | AlexJ [ Tue Jul 24, 2007 7:53 pm ] |
| Post subject: | |
Engine is running good. I don't have the stock prop. I'm the second owner. |
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| Author: | okboater [ Wed Jul 25, 2007 9:32 pm ] |
| Post subject: | |
Shift it into gear and see if you can turn the prop by hand. Might have spun your hub.... just a thought. Obviously, do this out of the water with the engine off..... |
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| Author: | AlexJ [ Thu Jul 26, 2007 7:11 am ] |
| Post subject: | |
Prop stays put, no spinning. Is there a big difference between a 14.25 X 19 and a 14.5X 19? |
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| Author: | Jim_R [ Fri Jul 27, 2007 2:40 pm ] |
| Post subject: | |
Probably not that much difference, maybe a couple hundred RPM. Although it is worth a mention that wih the 14.25x19 prop FW places the speed at 34 at 4000 RPM, right about where you are. http://www.fourwinns.net/fastfacts/fastfact/1999/238vi.pdf |
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| Author: | AlexJ [ Fri Jul 27, 2007 10:35 pm ] |
| Post subject: | |
What size prop puts it at 41 mph? |
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| Author: | Jim_R [ Fri Aug 03, 2007 8:39 am ] |
| Post subject: | |
The AL 14.25x19 does, but only at higher RPMs. Squeezing those last 400 - 600 RPMs out can take some time and a fine touch with the trim controls, at least on my 200. |
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| Author: | NHPilot [ Wed Aug 15, 2007 9:12 pm ] |
| Post subject: | |
Hmmmm. Seems to me that with a spun hub, the rpm would increase, not decrease. Also, unless the prop hub had completely broken free, I doubt you could turn it by hand as suggested. If that were the case, your rpms would jump way up and the boat wouldn't move. I am curious to find out what would limit your rpms though. 
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| Author: | AlexJ [ Thu Aug 16, 2007 8:08 am ] |
| Post subject: | |
After spending some time on Lake Ontario and trying to figure out the trim to get up to speed, I'm going back to my 14.25 X 17 prop to get my rated RPM'S at WOT ( 4800). I also forgot about the water tank. At 25 gals. of water at approx. 8 lbs. per gal. I had an extra 200 lbs of weight on the starboard stern side of the boat that I really didn't need. |
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