kinda what i am asking. if it is bolted to ground, he needs to find out what it is supposed to ground. if it comes from something else, it needs to be grounded to do it's job. if other end is bolted to ground, grounding the free end will do nothing.

Purple wire is an ignition 12+ it probably goes to your choke.

Purple/white might be a trim limit but it probably would not be next to your distributor.

it has a vacuum operated choke

What is your idle speed when setting base timing?

~700rpm

Distributor was removed to remove intake. Could it be off one tooth.

why did you need intake gaskets in the 1st place? Replacing them with new did you torque the intake manifold bolts in the correct pattern and correct torque in 3 passes.

Maybe an air intake leak at the manifold or water leaking into a cylinder or 2. from improper manifold gasket seal. What does your spark plugs look like ? any water on them or spraying out of the cylinder/s.

Also make sure that the ignition sensor under the distributor is hooked up correctly and grounded correctly. If this is the orignal sensor under the dist. cap I would replace it anyways. Merc had a SB years ago for a newer style sensor to replace the old one.

Next put some inline sparkies to make sure you have fire in all spark plug leads. You can also use a timing light for this while the motor is running plus check for misfires.

Timing should be good then, assuming distributor is in correctly as was just mentioned in an above post

Agree with Rookie the purple wire is 12 V and hook up for an electric choke app. The Purple and a black wire are for electric choke as in this app they hook to nothing being a 4 bbl manual choke app. It is pre wired and used in the 2 BBL carb apps for an electric choke.

The reason - Merc can use the same wiring harnesses thru out whatever the carb app is going to be. If the choke is manual leave the puple & black unhooked and if its the 2 bbl carb with electric choke the purple gets pushed hooked and the black screws on. Now you know where those 2 wires go.

Anytime a marine motor is work on at a true marine shop the first thing the tech does is look up the motor serial # to make sure he knows what he has.

This also helps with parts look up and what OEM service manual to look into for service help & specs if needed.

It makes no difference what year the hull is. Post your motor serial # inwhich can help out others that are trying to help fix it. The pics are somewhat hard to see what wiring is hooked into what wiring and so forth. Good luck with it.

Engine Serial Number is OF284281