69' merc 500---no top end

[canblue5]

engine starts fine, runs very well. no top end power.crack throttle wide open and boat only runs at about half speed. put engine in tank and removed prop, engine screams with power, put prop back on and back to running at half speed.I have rebuilt carbs,replaced pionts,plugs,wires,cap.new water pump and impellor.I know nothing about outboard engines but it is almost the same as timing is out on vehicle engine. is it possible to set timing on outboard? thank-you

 

[phatmanmike]

Re: 69' merc 500---no top end

i know you dont wanna hear this, but you really need a manual.<br /><br />30 bucks well spent.<br /><br /><br />1. dont rev an outboard without the prop.<br />2. are your carbs opening fully?<br />3. what size prop is it?<br />4. what size, make, type of boat is it pushing?<br />5. yes, you can set the timing on an outboard<br />5a. you can also royally funk some zhit up if you mess with that old merc linkage. you may need a " lync-n-sync".<br /><br /><br />but get a manual

 

[canblue5]

Re: 69' merc 500---no top end

thank-you for the info,,going to put this in the hands of the professionals.as my head hurts,lol.

 

[Texasmark]

Re: 69' merc 500---no top end

Hey Myoutboards, that's a Wankel automotive engine, not a marine engine.<br /><br />Mark

 

[MercFan]

Re: 69' merc 500---no top end

nm

 

[phatmanmike]

Re: 69' merc 500---no top end

hey texas, im about to prove you wrong.....<br /><br /><br />go to atkinsrotarymarine.com and click on " marine catolog"

 

[timmathis]

Re: 69' merc 500---no top end

Sorry canblue we are off topic. But that can be eather auto or marine rotory motor advair both work same way!

 

[timmathis]

Re: 69' merc 500---no top end

Canblue, Try pumping fuel bulb and see if it helps to get rpm's up. If so Bad fuel pump or supply? Tim

 

[Texasmark]

Re: 69' merc 500---no top end

Hey my, I'm headed there.I'm headed there. Grin<br /><br />Don't know what i'm going to see, but it is (at looks like) a Wankel.<br /><br />Mark

 

[Texasmark]

Re: 69' merc 500---no top end

Hmmmm, how about that. Did I miss something, or is this accurate. <br /><br />From the fuel consumption sheet I noticed that at 232 hp, the test unit was consuming .5lb of fuel/hp/hr.<br /><br />Unless I missed something that's 232(hp) x .5(lb/hp/hr)/7 (roughly....lbs/gallon) = about 16 gallons per hour.<br /><br />My 120hp Chevy II 4 banger (auto engine adapted to a marine environment) would run out at 4 gph, so if it were to double the size to 240 hp (comparable to your dyno report) it would run around 8 gph.<br /><br />Looks like you are gaining in weight, getting 230 hp for 350# of weight, but paying the bill at the pump.<br /><br />As I recall that was the reason Mazda dropped the Wankel design years ago......couldn't get the mileage out of it to satisfy the consumer.<br /><br />But you're right sorta; auto engine adapapted to a marine environment.....but when Mr. Wankel developed it, I don't know where he planned on using it....so I don't know....but so what.<br /><br />Hope you are enjoying it......one thing though, they were surely smooth running hummers.<br /><br />Mark