Prop help Lowe deck boat

[riknkeri]

1994 19' Lowe deck boat 27 g fuel and two adults. 1994 120 hp evinrude 14x17 alum prop... 32 mph (GPS) 4700 rpm.. Book says 5000-6000 rpm. Which prop do u guys recommend? Thanks

 

[buckinrut25]

First thing I would do is verify that your tach is correct. With these numbers assuming you have the 2:1 gear, your slip is 13.5 which is good. a drop to 15p should land you around 5100 rpm and accounting for you slip 31.22mph. The drop to a 13P should put you around 5500 and accounting for slip 29.35mph. If your happy with your boats performance I would go with the 15 but if you want to improve your acceleration and hole shot the 13 may be in order.

 

[riknkeri]

So goin down on pitch is gunna raise the rpm and lose mph.. I was actually expecting a little faster from a deck boat. Would running like it is at 4700 rpm gunna hurt engine. How do u check tack is right besides taking to shop. Thanks for input

 

[steelespike]

Do you have a model number of the boat? Lowe has 19 footers up to 1500 lbs with typical being 1100 or 1200.
You may be able to borrow a shop tach.
You could check the selector switch on the back of the tach;note its position and operate it a few times to clean the contacts.

 

[SkiDad]

can you move your engine up a hole ? that speed does seem a little slow... i would expect at least 35 but more like 40 and a higher rpm. Have you verified spark on all 4 cylinders ?

 

[riknkeri]

It's a Lowe 1900 and yes spark and compression is good just had stator and power pack replaced right after I bought it..... Ouch!!!! I was expecting 40 mph to hate to buy prop if it's not gunna help... As far as motor up a hole I'll have to check.. Again. Thsnks

 

[steelespike]

If someone has been messing around under the hood I would want to be sure of the simple stuff.Is the throttle opening all the way.
Is there a timing setting and is it right? Don't assume all is right from recent work.A plug wire might be off.
Its not unusual to not realize your down one cylinder except for the lack of power.
The Lowe 1900 is 1500 lbs dry weight. I think a 120 should handle it easily with a 17" prop.
If you wanted to make 5500 rpm you would need to go to about a 13" prop.Thats pontoon size.
You might squeeze in at about 5100 with a 15" prop.
At this point I don't think raising the motor one hole will solve anything unless it is set up really low.
Does the boat respond to up trim?

 

[jestor68]

I'm with steelespike; it appears you have motor issues since it should be able to turn a 19 pitch to about 5000(+/-) rpm, according to the prop selector.