70hp evinrude trouble

[bryan75411]

I recently acquired a '84 70hp evinrude on a 15'4" Astroglass fishing boat. When I first got it running, it would run lean and I would have to choke it to get it to pick up and plane out, and it would barely idle at all. Now I have cleaned carbs and gotten it to idle smoothly and it will run great at idle in fwd/rev, but now it will not plane out. I feel that I have opened the lower(I guess those are for high speed) needle valves up too much. they were very tight when I first checked them, so I opened them up 1.5 rounds and now I am having this problem. Can anyone tell me a good place to try initially setting the lower adjustment for the 3 carbs?<br /><br />Thanks for any help!

 

[jim dozier]

Re: 70hp evinrude trouble

I believe your engine has fixed high speed jets. They would probably stick down into the carb bowls. The adjustable mixture is for the idle speed. Most (unless your manual says differently, you have a manual don't you) should be opened up about 1.5 turns from the gently seated position (screwed all the way in). Set idle speed to ~700rpm (check the manual that you just got) and fine tune 1 carb at a time, resetting idle speed if necessary between carbs. When you rebuilt your carbs did you remove the high speed jets and clean them with solvent and compressed air? Sounds like you are describing clogged high speed jets. You've had to open up the idle jets beyond their normal range because your high speed jets (which also feed fuel to the idle jets) are restricted.