Dhadley........Talk to me!!!!!!

[85Sunbird]

Re: Dhadley........Talk to me!!!!!!

I have another thread called "1977 115 Evinrude Performance upgrades"....I decided to move it over here to keep all this in one thread.<br /><br />I have a 1977 115 Evinrude that I would like to try and get somemore power out of. I have already done the following to the motor as far as upgrades: 135 heads (155 psi compression across the board), 135 carbs, 135 exhaust (block was not cut out for it though), bored .030" over with a set of wiesco pistons. With the help of Dhadley I have improved my setup and the boat responded really well to the changes. I'm running a OMC 19" SST prop that has been trued and reworked to factory specs. I was only turning about 4800-4900 rpms before and since I raised the motor I've turning around 5300. <br /><br />I hear all the time where people are turning these motors 6500+ and I just can't figure out how they are doing it. With my boat design, I'm about as high as I can go with my motor height. I can go to a smaller pitch prop and gain rpm's but I loose alot of speed i the process. <br /><br />I guess my question is, what are some performance upgrades I can do to the motor to gain more rpm's? I don't want to tear the whole motor down again just yet, I'm mainly talking about intake mods, exhaust mods, etc, etc.<br /><br />Dhadley.....I know you said to let's get my setup optimzed first but, I think I'm as good as I can get. Can you tell me more about the plenum intake?<br /><br />Thanks again:<br />Jason

 

[Walker]

Re: Dhadley........Talk to me!!!!!!

Personally, I'd leave a 27 year old motor alone other than setting it up with the optimum heighth and prop.

 

[85Sunbird]

Re: Dhadley........Talk to me!!!!!!

Dhadley,<br />I ran the boat again this weekend. I hadn't made anymore changes since we last talked. I was able to play with the trim alittle more and acheive 5400 rpm's saturday and speed or 49 mph. I have niticed that if I trim the motor out to where it will throw a nice rooster tail, that is when the motor turns the most rpm's and runs the fastest. <br /><br />I know I probally need to go to a jackplate but I have some concerns. I'm running that CMC aftermarket tilt and trim unit which sets the motor back about 5-6" off the transom. My transom has got some flex in it and I'm affraid if I add another 4" or so jackplate unit to it, that it will be too much on the transom. What do you think? Are you able add a omc style tilt and trim to a 1973 motor? I need to get more height on my setup but I'm to my max right now. <br /><br />Also.....Is there such thing as a homemade manual jackplate? Has anybody ever done this before?<br /><br />Thanks:<br />Jason

 

[85Sunbird]

Re: Dhadley........Talk to me!!!!!!

after I get the height settled...then I would like to find a good raker prop.<br /><br />Jason

 

[iRich]

Re: Dhadley........Talk to me!!!!!!

a little flex in the transom? That doesn't sound good, better check it out.<br /><br />Rich

 

[85Sunbird]

Re: Dhadley........Talk to me!!!!!!

yea Rich,<br />I know that transom is weak. We're in the process of trying to brace it off. I can't afford to have the transom replaced right now. It does't flex that much except in choppy water the motor will bounce back there and crack in the well where a recessed cup holder is. It's hard to explain...maybe I can post a pic of what I'm talking about to make it clearer.<br /><br />Later:<br />Jason