70hp Evinrude carberator rebuild

[EBBTIDE 78]

I have a 1977 70hp Evinrude. Low idle is rough and sometimes will stall. Motor will bogg down when you run it at high speed for a min or so. I do believe a carb rebuild is in order. Is this rebuild an easy task? Then after I rebuild them, do I just put them back on & go? I read in the manual that a link & cink should be done. <br /> I also have noticed that there is black residue, soot of somekind coming from the pressure valves at the midsection of the motor. What is causing this?<br />Any further hints and tips are welcome.

 

[Silvertip]

Re: 70hp Evinrude carberator rebuild

Since stalling is a problem at idle, and it loses power at high speed, the very first checks should be to make sure the fuel pickup in the tank is not clogged, the tank vent is open, the primer bulb is not being sucked flat, and that there are no air leaks in the fuel lines and fittings. If those are all ok, then you might look at carb idle mixture and idle speed settings (do this in the water, not on muffs). If stalling at idle can't be corrected then rebuilds are likely needed. Instructions come with the kits. Since you have disturbed the linkages when you remove the carbs, link & sync is recommended to make sure the carb butterflies are all closed at the same time and reach wide open (perfectly horizontal) at WOT and that the ignition timing is correct. You need a service manual for this -- its far too detailed to go into here. Check your library.

 

[KYHunter2]

Re: 70hp Evinrude carberator rebuild

The black soot , stuff. That is coming from exhaust relief holes.<br /><br /> Is probably just some unburned fuel, mixed with exhaust residue.<br /><br /> KYhunter

 

[EBBTIDE 78]

Re: 70hp Evinrude carberator rebuild

To inform you, this problem has been solved.<br />This loser that rebuilt all three carbs, was an idot. He reused the old floats, they all three were corroded, bubbled, cracked. The low idle screw in the middle carb was incorrect. Too big, practicly stripped out, but he did manage to leave me a little gold dust there. The gasket material used was from sheet material, cut out to look like a gasket. Top butterfly was open a touch, bottom was open just a little more than the top. <br />Any way, I had a total 3 carb. rebuild, link-cynk and three times around the big pond. She runs great.<br />Thank you for your input