1985 Merc 115 in line 6

[CharlieB]

Re: 1985 Merc 115 in line 6

You can set timing cranking at home, once on the water you may have to make a small adjustment to perfect the idle speed.

4 ATDC should get you real close to a good idle speed in the water.

Running on the hose idle about 900 - 950 then when in the water the back pressure will cause it to reduce near 700 maybe.

 

[Chris1956]

Re: 1985 Merc 115 in line 6

I do not agree on changing the timing during water test. Set idle pickup timing to 4-6* BTDC and max timing to 21* BTDC, and lock them in. That is the whole point of link and synch. You may adjust idle stop while on the water, as well as idle mixture adjustment.

 

[rrumba]

Re: 1985 Merc 115 in line 6

Chris,
just to be clear, idle mixture adjustment you mean the ones on the 3 carbs, correct?

Now that the traffic on the lake should be down, hope for tomorrow to get on the water and try to fine tune it some more with the carbs and just minor changes on the water.

This is starting to wear me down trying to get it to run right..... i am almost at the point of finding someone to take it to and call it quits. :blue:

 

[Chris1956]

Re: 1985 Merc 115 in line 6

Yes, Idle mixture adjustment is the three carb screws. Normally you start them at 1-1/2 turns out from lightly seated. Normally you will need to richen them a bit to get the motor to accelerate smoothly.

Remember idle speed is controlled by idle stop screw, except that throttle cable must push throttle arm into the stop screw, for it to stop throttle. If throttle cable is not adjusted to push throttle closed, idle stop screw will have no effect.

 

[rrumba]

Re: 1985 Merc 115 in line 6

chris,
i believe this has been stated and just looking for clarification. the throttle roller for the carbs should not be touching the cam on the linkage at idle, but just off of it a bit so when you put it in gear the timing has a chance to advance before the carbs are advanced. Do you know how much that gap should be or can you just eyeball it so there is some space between them? I do not believe that it is set this way right now.

 

[CharlieB]

Re: 1985 Merc 115 in line 6

Watch timing while cranking, advance the throttle arm until timing reaches 5 BTDC. Hold the lever right there, loosen the carb pickup and back it up til 'just touching'', carbs should be completely closed. tighten the set screws.

Pull control arm/throttle arm back to idle. See the gap.

Check your work.

Cranking, idle timing @ 4 ATDC

begin moving control arm and watch timing advance to @ 5 BTDC where the carb linkage pickup contacts

WOT timing at 21 BTDC

 

[dethalis]

Re: 1985 Merc 115 in line 6

Just would like to add I wonder if your prop inner hub is spun or if its plastic like mine is cracked causing the prop to slip and thus causing the engine to flood as it cant use the fuel that is being supplied... my mechanic and I found out that mine had a broken inner hub and am getting the prop repaired this week..