1984 - 351W - High Idle, Mechanical Advance Stuck?

Hi Everybody,

Trying to figure out my next move. I have an 84' 2001 with the 351W and it runs really well but seems to idle high after warming up and running for a bit. When I bring down to neutral my idle stays at or slightly above 1,000 rpms. Also there is at times some slight hesitation when hitting the throttle (this could be as easy as a carb adjustment though, haven't really looked into it) I just got the boat in late September so only out a handful of times. My questions

1. At what RPM should it be idling? When warming up its around the 600's.
2. I have been trying to read up, could the mechanical advance be stuck after running and not springing back at idle? and if so, what would be the best way to resolve the issue?
3. How do i determine the engine rotation?

Any thoughts and or other threads to read would be much appreciated.

Thank you!

Along with what JQ said about the distributor, I'd also look at the carburetor when the idle hangs high.

When it's idling high, with the engine still running, see if you can push the primary linkage farther shut. If you can and the idle goes back to normal then it's time to look at the return spring on the carburetor primary shaft or the separate return spring that is a lot bigger and goes from the linkage to the intake manifold or a bracket on the manifold. The spring(s) could be weak or the throttle cable is not aligned very well causing the linkage to hang up.( Or the shaft itself is binding)

You can also try pressing on the secondary linkage to make sure the secondaries are against their stop and not hanging open slightly

The picture shows the primary linkage where the throttle cable hooks up,and also the separate spring and the secondary shaft linkage with the bent rod that goes between the primary and secondary linkages to insure that the secondaries are never more open than the primaries.

You can't see the spring that goes around the primary shaft in this picture, it's behind the big plate that the throttle cable and other visible spring are hooked to.





By the way, in the picture above either the primaries are open some or the link arm to the secondaries is way out of adjustment. Here's what it should look like at idle

Keno
Thank you for the input

GottaSki, You are correct the condition clears itself especially if the boat sits for a little before going underway again.

How would you work to clear idle orifices? or where would you direct your attention to solve the issue?

Let the reading the begin, i am sure there will be some more questions to follow! Appreciate the help!

There are around 1,250, what would that entail?

The idle fuel orifices are in the metering block and behind press plugs that you don't wont to remove.
A thorough cleaning and compressed air check are in order. Teh orifices are so small the difference between plugged and not, is really challenging to resolve.
Also the state of fuel filtration had to be considered for the fix to persist.

Basically, compressed air to the idle mix screw (hole) should flow out two ports, one to the idle air bleed on throttle body side, one to below fuel level on bowl side.

Started to take a look at the issues and from just looking around the carb the link arms to secondaries seem to be where they need to (without running just looking). Looked at the distributor found out i have electronic ignition and looked below and the mechanical advance seemed to function properly. I did look at the choke and it was not connected properly. I first tried to just move the choke and it did not move the butterfly at all. As it sat butterfly was fully closed. I took off the choke mechanism and re hooked and adjusted the butterfly to be slightly open. I am going to make sure it has +12V probably today but this might help. I will continue to update once I start the boat here in a couple weeks as some of the recommendations involve the boat running.