Timing problem

[andrewterri]

As stated before in another post, I followed the great direction from slow_boy on how to set the timing on my 1989 mercrusier 3.0. I have set my dwell angle at 33 degrees as that shows it is within range according to the engine label. I have set the timing at 6 degrees BTDC, again, as stated on the engine label. The engine stopped trying to shake itself out of the boat, however it is not holding the timing. While in the water running and engine at proper operating temp the engine will sometimes idle smooth and other times it going back to shaking very bad. Not sure what to do? Points, condenser, cap, rotor, and plugs have all been changed along with connections in distributor being cleaned. The lock down bolt on the distributor has not came loose. I had to use a picture provided to me from this forum to know where 6 degrees BTDC because the tab is rusted with no writing remaining. Positive it's right because at times it idles smooth and timing is on. Any help sure would be appreciated.

 

[Fishingaddict88]

Did you allow the engine to get up to proper temp prior to setting the timing?

 

[Scott Danforth]

did you re-tighten the distributor clamp?

 

[Maclin]

If the mechanical advance inside the distributor is not working smoothly then it is possible that when you are setting the timing it is advanced some, and then when it does return back to no advance the timing will be off.

With the distributor cap off, try to turn the rotor gently. It should move some, then snap back smartly when you let go. That is the centrifugal advance action, comes into play as the RPM's increase, If that action is not smooth, or the return action is not sharp then it needs serviced.

 

[Bt Doctur]

Try setting the point gap at .018 and disregard the dwell

 

[andrewterri]

Thank you all for the solutions. Today my wife, daughter, and I went to the lake and the boat ran nice and smooth at idle in gear but neutral it was very rough again. It shakes very hard. I have rechecked the distributor bolt and its tight. I have not set dwell at .18 yet and was curious... does the dwell change as a boat ages or is .18 gap just better? I started at .18 but dwell angle was to high and had to increase gap to .21. The advance is working but i will recheck it. When putting new rotor on I put pressure on shaft and rotated it and it popped back. I was not looking for that so it might not be as described so I will check tomorrow. I think I have a bad valve seal as there is smoke and oil coming out with exhaust, I don't know if that will affect it. Also, there is black smoke in exhaust which is excess fuel and I have turned the mixture screws in and still need to adjust them. I made the mistake of buying an I5 carburetor and the mixture screws were 4.5 turns out. Set them to 1 1/4 as I am assuming it is like a factory carb. When I called them and asked for the setting I was only told the carb is ready to run as is and was preset.

 

[andrewterri]

Oh, forgot to add that i did allow the motor to warm up before setting the timing. Assuming, I know what that means , the gauge is working correctly the temperature gauge showed normal operating temp when I set it at the house on the muffs.