Mercury 850 85hp carb setting

[Trucker-Boater]

I need someone to direct me. I have this 85hp on the back of a 14 foot Glasspar. Circa 1965. Today the motor out on the lake died when I cranked a hard turn. Like it was running out of gas. It just slowly ran out and quit.

I had a full tank and only had been out on the water for a few minutes. I pumped the bulb up and it ran fine.

I do notice a slight shudder--at 50% power. I stand on it. It runs good.
But a steady run I can feel a slight shudder-studder like a carb is dirty or maybe electrical. That is annoying. I can feel it in the hull slightly misfire (studder) then run better for a bit then stumble just slightly--then again runs nice.

I have the Stylmar (sp) manual. I'm thumbing thru it. Trying to make heads or tails about this.

What I may need to do is swap out the distributor cap. It looks like it has been on the engine a while. Below the cap is there a rotor like you would find on a car? If so, I probably should swap it out too. The engine does have new plugs. I just did a shift seal. And swapped the impeller and lower end oil.

Carbs--Is there an adjustment on them? Rich Lean? Where on the carb is the adjustment to lean them out a bit. I noticed when I was home and running out the rest of the fuel for storage with the muffs on, it ran pretty good as the fuel was running out. I get the impression I might be a bit too rich on the settings.

I need some pictures to help me along here.

 

[Chris1956]

Re: Mercury 850 85hp carb setting

Trucker, The rotor is non-removeable. if you try you will break it and need to replace whole shaft and rotor for $200+. Distributor cap is also big bucks, if you can find one.

Look at the wiring harness. Usually they are shot by now. Maybe the wires short when you turn? Maybe the main plug disconnects when you turn?

Clean the dist cap. Check the plug wires for arcing. Get a service manual and clean and rebuild carbs with new gaskets, inlet nedle and seat and float.

 

[Chris1956]

Re: Mercury 850 85hp carb setting

There is an idle mixture screw on each carb. CW turning leans mixture

 

[Trucker-Boater]

Re: Mercury 850 85hp carb setting

OK here is what I am facing

Actually the cap and rotor are in decent shape. God knows how to remove that cap with it all installed. But---

I found one plug wire end (closest to you when standing and facing the engine with the prop on your right). I took the clamp off and looked inside the cap. Not bad. Nothing burnt. I put it all back together but am having a hard time with one plug wire inserting into the cap.

PARTS--OBSOLETE Obsolete OBSOLETE! AM I screwed or not? I was told to use some carb cleaner and douche the carbs. Quicksilver makes one which I can get at West Marine. $12-

I leaned out the carbs 1 turn. I fired things back up after pushing the end back into the cap securely. The engine ran pretty good. I maybe be over oiled in the fuel tank. I might of put too much oil in, but its running.

I would feel really good having a new cap and rotor. But not being able to get parts....

I do want to swap in new plug wires. I think I can make those myself.

Cap and rotor...no one has anything. Rotor is permanent and even if I did have a new cap--how the heck does it slip in and under the rotor???? So the diszy needs to be removed to get the cap on...lovely!

ideas? I am checking the wiring harness. It looks ok from the surface and at an idle. I need to concoct a
garbage can to put the prop and lower end in so I can run things up high. I have a muff installed but is this like my Stern Drive Mercruiser??? Where you cannot idle up or run at a fast idle without tearing up the impeller???

 

[Chris1956]

Re: Mercury 850 85hp carb setting

You may run at fast idle on standard flusher device. Dist. cap is removeable easily. Remove cowling support bolts to allow lower cowl to drop down some. Wires screw into dist cap. They have special ends crimped onto them. Try oldmercs or vintagemercs website for plug wires. They are called Tiger tails and are $6ea. The conductor is stranded stainless steel.

 

[Trucker-Boater]

Re: Mercury 850 85hp carb setting

Thanks!

 

[Silvertip]

Re: Mercury 850 85hp carb setting

The mixture screws you are messing with have no effect at cruise and high rpm. That's why they are called "idle mixture". If the engine runs fine at high rpm you don't have a distributor, rotor, or wire issue. It would likely act up more at top end than mid-range and idle.