New to me 850 mercury

[Turbovert]

So I just picked up my first project boat. It’s a 1981 glastron Carlson c500. It needs quite a bit of work but hull looks solid and it was $300 with trailer. It came with a 1973-1975 85hp mercury from what I could come up with. It needs tons of work. I’ve ordered both wire harness and ear muffs so I can even begin. I’m new to outboards but not mechanics or other motors so plenty capable of working on it. I can’t seem to find a downloadable shop manual for it? Also it has two rubber tubes coming out of crankcase, one at top and one at bottom, that look cut? I’ll need to get a hydraulic lift pump but the four lines are there coming out of cylinders. Any and all advice very much welcome.

 

[Turbovert]

Also anyone have a picture or diagram of the throttle and shift linkage setup?

 

[1960 Starflite]

I have the same engine on my pontoon. Replaced a magnito driven 650. Mercury really screwed up the wiring system on the 70's engines. Some bean counter must of had a Brother-in-law in the wire harness business. Even if you remove the covering from control side you'll find insulation cracked from engine to control. Mine runs great (4 years now). Timing was way off, (belt off a tooth). Carbs, hoses and fuel pumps rebuilt, link n sync. It sure does like fuel what you gonna do?

 

[Chris1956]

That motor has some challenges. None serious. I assume that you have never seen an intact version of your motor. That makes it tricky.

The first thing to do is to test the ign system. You need one for a battery-powered CDI unit. Do a search on clams canino on this forum for a ign test. CDI Electronics may also have the test. Basically it test the wiring, switchbox and assumes the coil is good. If it fails the trigger is likely bad.

Those triangular fittings on the starboard side are fuel pumps. Some motors had two, some had one. They are good, but the fuel lines had built in brass threaded fittings, and are hard to find. You will likely need to make them up with brass nipples, fuel line an clamps. Rebuild the fuel pumps.

The wiring harness is trash. You need one for a battery-powered CDI unit.

The original Power Trim/tilt system had a pump/reservoir in the boat. It was an add-on, so the PTT wiring was standalone. Good luck finding one.

 

[dwco5051]

If you ever have to remove the flywheel it is just the large nut in the center and the proper puller. Do not disassemble the flywheel by removing the 8 bolts before making witness marks with a scribe or paint as it can be put together in the wrong orientation.

 

[Chris1956]

Actually DWC, I disagree. You can replace the stator by pulling those 8 5/16" bolts in the outer flywheel. Much easier than using a puller. You don't even need to remove the inner flywheel when rebuilding the engine, only when you are replacing the timing belt.

Match marks on the two flywheel components make is easier to install the outer flywheel correctly, however, each bolt hole represents 360/8 or 45* of timing. if you cannot tell the difference between top dead center and 45* away from TDC, you have other issues.

 

[Faztbullet]

Before you inverst any $$$ and time on this check compression and ignition system. If either is bad you will spend more than its worth.