muff idle and in water idle

[sparkroost]

115393M 115hp evinrude.<br /><br />I have not kept track of hours on the motor since rebuild, but have kept track of fuel used. Is there a magic number to look for is fuel consumption?<br /><br />I am having a problem with out of water idle at 1200, but in water goes to 700-800. If I set the muff idle at 1000 pr. manual I am getting around 500 rpm. Once warmed up the engine will idle at 500-600 without stalling. also.. I have the idle adjustment screw all the way in. I have set the link and synk set to 5 deg at the center of the roller and the slash mark on the cam. I do have some wear in the throttle shaft where I can see the butterly slightly rocking up on the actuator side. low, mid range, and high end are very smooth running with no heavy shaking. At idle there is a little shake every now and then.<br /><br />Why do I have to have the idle screw in all the way(1200 rpm).. also.. if I give slight throttle the cam is moving the roller which is giving excess throttle and the engine will want to raise in rpm dramatically(say from 800 to 1200, I am recalling from memory)... example. If in reverse at 700 then I want to get it to 800-900, it may go right to 1000, then I am too fast in reverse.<br /><br />Plz keep in mind this is with a 24:1 mixture, but I dont think this is contributing to my problem to a degree that will change significantly once I goto 50:1.<br /><br />Any help would be appreciated.<br /><br />P.S. compression is at 150-152 pr. cylinder, new coils, wires and champ Ql77JC4 plugs set at .040.

 

[sparkroost]

Re: muff idle and in water idle

^

 

[DJ]

Re: muff idle and in water idle

sparkroost,<br /><br />The idle should be set with the engine in the water. Setting idle "on the muffs" will give erroneous readings.<br /><br />The in water setting is needed because the engine needs backpressure to idle at spec.

 

[sparkroost]

Re: muff idle and in water idle

welp... I have the idle screw all the way in to run properly in the water...isn't that strange..? She runs like a top other than the idle drop.

 

[Solittle]

Re: muff idle and in water idle

sparkroost - 1000 to 1200 rpm on the muffs and 7-800 rpm in the water is normal and the difference is due to the back pressure of the exhaust when in the water.<br /><br />Set the carbs per the shop manual.<br /><br />Great motor.

 

[sparkroost]

Re: muff idle and in water idle

Something is not right. My 77, 85hp rude runs nothing like this one at idle. The idle stop screw is about 1/2 way.<br /><br />Could it possibly be a poor fuel octane problem due to high compression?<br /><br />Do you have any idea what the idle would be @4 degree advance out of water, or in(I am saying 4 cause at 5 the throttle plates are slightly starting to open.)?

 

[OBJ]

Re: muff idle and in water idle

Hi sparkroost.<br /><br />Djohns is correct. The engine needs to be in the water to set the low end idle. Muffs just don't get it for this process.<br />Also, it almost sounds like you are setting the timing to the throttle cam roller position instead of the other way around.<br />Is the throttle plates in sync? With the engine warm and at "idle", loosen one of the throttle plate adjustment screws and see if the engine idle changes. If the idle does change, one of the throttle plates was open slightly. Redo the throttle plate sync.<br />Last, try doing the whole set up from scratch with the throttle cable disconnected.

 

[sparkroost]

Re: muff idle and in water idle

ok, let me explain how I set the pickup timing. I found out where 5 deg. was on the arm and moved it there. Then I adjusted the roller and the yoke so that it makes contact with the scribe mark and the center of the roller. (The book was terrible at explaining this procedure.) So now when I advance the throttle, the butterflys are just starting to open when the scribe mark makes contact with the center of the roller and the timing is at 5 degrees at this point. The only thing I can see the idle adjustment screw doing is advancing the timing.. then when 5 deg advance, the carbs start to open.<br /><br />Did I miss something?

 

[sparkroost]

Re: muff idle and in water idle

dang it! now I am pissed I didn't bring my manual to work! I got the half baked procedure from a clymer manual. I have a good factory manual at home, but it's for a 1972 100hp V4. Gonna check the procedure in there when I get home.<br /><br />I tried doing a search on link synk, pickup timing, etc and can't find a procedure. The clymer manual jumps from certian years to other years. It was easy to get lost there. If someone has a set-up digitally remastered(scanned copy), please send it to me @: kismet@houston.rr.com

 

[sparkroost]

Re: muff idle and in water idle

ok.. my link and synk was correct... but... in the procedure it states to turn in the idle screw until 5 deg. advance is reached for the alignment of the scribe and the roller. Screw is too short to obtain 5 deg. adv.. I guess it's possible that someone changed the linkage arm to the timer base. I have about 1/4" gap before the idle adjustment screw will make 5 deg. adv.. I added a longer bushing to the end of the screw and presto! <br /><br />I would rather have a shorter timing actuator rod though.<br /><br />Has anyone experienced this? I talked to a veteran outboard mechanic and he said that they changed the linkages often as there are different part numbers for different years.<br /><br />I compression is getting higher. 158-160 psi now, warm. Is there a scale of compression #'s to pump octane? I am getting a little worried about pre-ignition.

 

[Hooty]

Re: muff idle and in water idle

Just adjust the carb link & sync, adjust the wfo spark advance and let the pick-up advance take care of itself.<br /><br />c/6<br /><br />Hooty

 

[sparkroost]

Re: muff idle and in water idle

Hooty, if the pickup advance is not right it will bog out of the hole.. 5 deg adv. is needed for proper transition from low to high rpm.

 

[Hooty]

Re: muff idle and in water idle

O-K<br /><br />c/6<br /><br />Hooty