Prop selection

Joined
Jul 11, 2003
Messages
6
where can I find out which prop I should use for a 1963 40 hp johnson. I have a 14 ft 1963 starcraft fiberglass boat and don't think the motor is performing like it should? It runs smooth but seems like it should run faster. maybe I am just expecting more form this motor. :confused:
 

roscoe

Supreme Mariner
Joined
Oct 30, 2002
Messages
21,750
Re: Prop selection

For the most part, prop selection should be based on your wide open throttle rpm's, not what you want it to do.<br /><br />You want your engine to achieve near maximum recommended rpm, with a light load in the boat.<br /><br />If you change to a prop with a higher pitch, you will lug your motor and could severely decrease its life.<br /><br />If you change to a prop with less pitch, you will improve your holeshot, but run the risk of over revving your engine. But you can prevent this by watching your tach, and throttling back if necessary.<br /><br />So the question is, what WOT rpm are you running now? <br />Second question is, how's your holeshot?<br /><br />If you don't have a tach, get one before wasting money on new props.
 
Joined
Jul 11, 2003
Messages
6
Re: Prop selection

thanks that was my next step is to find out what rpms I am running my book says I should be at 4500 rpms. can you tell me how I connect a portable tach so I can find this out all the book says is to follow the manufactory steps but I don't know what that is.
 

Hooty

Rear Admiral
Joined
Oct 2, 2001
Messages
4,496
Re: Prop selection

I don't know what kind of tach you have but here are a couple of websites that may help.<br /><br /> Teleflex 1 <br /><br /> Teleflex 2 <br /><br />c/6<br /><br />Hooty
 

binky775

Cadet
Joined
Mar 15, 2003
Messages
13
Re: Prop selection

i have a simular boat and the same motor what is your top speed.i can only get 20 mphon the down side of a big swell. i to think it should go faster
 
Joined
Jul 11, 2003
Messages
6
Re: Prop selection

I can't tell you what my mph is I have no gauge to tell me but I know the boat won't get to a plane and the speed is not much. I guess I will keep playing with it until I find the correct performance for the motor. but I sure am having fun playing with this and seeing if I can fix this fishing boat. :D
 

binky775

Cadet
Joined
Mar 15, 2003
Messages
13
Re: Prop selection

I was told by the prop shop that if it will get on plane that thats all you can expect.what number is on your prop.
 
Joined
Jul 11, 2003
Messages
6
Re: Prop selection

I don't know I can't find any numbers on the prop is there a way to find out by measuring the blades? :confused:
 

dustinatdana

Cadet
Joined
Jul 14, 2003
Messages
18
Re: Prop selection

mine is super fast it took almost a hole can of carb cleaner and new hotter plugs now she screams i can keep up with most boats
 

Cricket Too

Lieutenant Commander
Joined
May 14, 2003
Messages
1,732
Re: Prop selection

shadetreemech....Are you sure it is your prop? If you can't get on plane you might have a power loss somewhere before you even get to the prop, ie. carbs running too rich or lean, clogged etc..
 
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