1975 evinrude modifications?

[NJCoastFlyFish]

Can a 40hp 1975 evinrude be upgraded in horsepower anyway? New carburator maybe? I did a search and there was some talk of upgraded 9.9's but not the 40's

 

[NJCoastFlyFish]

Re: 1975 evinrude modifications?

The prop on it I have now seems wimpy, what better props would fit this engine?

 

[CATransplant]

Re: 1975 evinrude modifications?

The best way to upgrade a 40 hp outboard to get more horsepower is to buy a new one with more horsepower, quite frankly. Messing around with your motor will just make it unreliable and won't be of any real benefit.<br /><br />As for the prop, I'm not sure what you mean by "wimpy." Since you don't say what its diameter or pitch are, it's really impossible to say whether you could do better or not. What is it about the prop that makes it "wimpy?"<br /><br />This is a very helpful forum, but the more information you provide, the more help you'll get. Based on what you have told us, there's not much we can tell you.

 

[Chinewalker]

Re: 1975 evinrude modifications?

The best way to get "more power" out of any motor is to make sure it's actually putting out the rated power. Most aren't. <br /><br />Is the motor reaching rated RPM range? Is the compression good and even? Are all throttle linkages reaching full advance? Is the prop in good shape? Is the motor as high on the transom as it can be? Is the boat hull in good shape? <br /><br />I once saw a guy upgrade his 70hp triple to an 85hp V4, but he was disappointed when he only gained about 3 mph. Turned out he was carrying close to 700 lbs. in water saturated foam in the boat's hull. He gutted the boat and installed new foam and picked up 9mph!<br /><br />If, in the end you find that all is well with the boat, prop and motor, and you still need more power, then go with CAT's suggestion on simply getting a bigger motor. Any modifications you make to the motor will affect longevity and relibility and likely won't translate into any real performance increases....<br /><br /><br />- Scott