351W Timing set 30 degrees advanced

Keno, you explained it better than I. He has something off if it needs 30 at idle to run.
Balancers can fail and the outer ring with the timing numbers can shift. This is an 89.
I have never seen this in a boat but it is fairly common issue in classic cars from the 60's.

Looking down on the front of the engine, at the fan belts look at your two heads. One is about and inch forward of the other. The forward head will have the number one cylinder in it.   The first forward spark plug on that side is what you time to.
Check all 8 plug wires and the fire order for a 351W, not the same as a 302.
At 30 advanced at idle you will damage engine internals. Fix it first then go play.
Hope this helps.

Thanx for the reply.

The thing is that adjusting the timing while underway is how I get to 30 degrees.

The idle isa adjusted after coming out of full throttle operation,

Total agree that this is a great way to burn things up,

Motor doesn't ping or seem to complain but the only way to get any performance out of it is to advance the timing that far.

Having difficulty understanding how carburation issues would cause severely advance timing to run right but will rebuild carb just to eliminate as a concern.

Just trying to rationalize conditions.

Hello,

Have a troublesome timing issue that just doesn't seem to make much sence.

Purchased used - 1989 Ski Supreme Commander 351W

Ran boat on trailer and it sounded OK considering having sat for an unknown number of years.

Put unit in the water and it stumbled quite a bit off idle. On the way from the launch to the dock loosened the distributor and "adjusted" till it ran well.

Carb was dripping so the stuttering I chalked up to carb issues.

Cleaned carb and adjusted floats to get it running smoother.

When a timing light was attached it registered approx. 30 degrees BTDC. Not where I was expecting considering 6 degrees is what it should be.

As expected starting the motor with that much advance is a challenge. Starter tries but unless you cross your fingers it may not fire.

When cold boat fires up and idles well. Takes off pretty well (occasional stumble).

Looked into distributor and the mechanism appears to be free but the springs looked "crusty" so I decided that it would be easier to replace with a NOS unit from EBAY than go through a recurving process considering I was on a tight schedule to get this thing going.
The distributor on the boat had been modified with the Pertronix Igniter setup and the resistor removed.
Replaced the distributor and boat ran pretty much exactly the same and still required the 30 advance to function.

When timing the reading is stable (no shake) and put a wrench on the crank and checked timing chain play and didn't experience any "slop" when watching the rotor.

The new distributor had arrived with new points and condenser so after messing with the electronic conversion decided to put the points in and try it. Retained the Flame Thrower coil (1.5 ohm) and ran without a ballast for the weekend.

Boat runs the same .......

Temp stays around 170 according to the existing gauge so it's not running hot.

Driveability is good just don't shut it down.

I am going to verify TDC and have more than once checked the firing order.
Going to remove the valve covers and verify that the firing order matches the action of the valves.

Looking for suggestions................

Thanx