1963 75hp Link & Sync Not Working

[yorab]

I've followed the manual exactly--three times--but I'm still having a problem. The first step is to move the distributor to full advance and make sure that the inside edge of the throttle control shaft arm lines up with the triangular projection on the control shaft bracket. I've done that without issue. Then, disconnect the carb sync rod to gain access to the throttle arm clamp screw. I've loosened the screw and then lined up the sync mark with the center of the cam follower roller while holding the throttle arm in the closed position. Then I tightened the clamp screw. So far so good. Then I moved the throttle arm to fully open while holding a .020" blade between the throttle control shaft arm and the stop on the control shaft bracket. While holding this configuration, I tightened the set screw that holds the carb sync rod to the cam. These, I believe, are the exact steps stated in the FSM. Now when I back off of the throttle control shaft until it stops, the sync mark on the cam no longer lines up with the cam follower roller. This is shown in my pic. It seems that I must advance the throttle a bit before the mark lines up correctly again. This means that although the throttle plates are not opening because the cam is not pushing on the cam follower roller, the distributor is advancing from the get-go. The distributor is advanced some degrees before the throttle plates even open.

Is this correct? Does this mean that I simply need to adjust the idle control screw to keep the cam from backing off of the follower roller so far and thereby keeping the throttle plates open a bit? Does the fact that the distributor begins to advance before the throttle plates open suggest a problem or was this designed into the linkage? Thanks.

 

[boldtr]

Re: 1963 75hp Link & Sync Not Working

Hello Yorab,

Yes. This is correct. You can adjust the control screw so mark stops on the roller, this may run your idle just slightly higher. You want the throttle plates to be closed at idle which they are in your last pic. You are simply retarding the timing advance when the roller moves past the mark as you have shown, the carb plates are not changing and is still closed...only the timing advance is affected. You can actually get the motor to idle lower by doing this, but it will likely die once you put it in gear if too low. The key here is that the throttle plates are synced and fully open at the same time the distributor meets full advance. You have some room for error because of the spring that keeps the timing at full advance when the throttle is reduced. This will slightly close the carbs, but not change the timing giving you a boost in fuel efficiency. This is nice feature once you have the boat on a plane.

Don't get too hung up on trying to get this perfect. You are very close already.

1. I would use the throttle idle control screw to set the mark to stop on the center of the roller.
2. This may push the timing ahead just a hair and slightly increase your idle RPM
3. The slightly higher idle may be just what you need to keep the motor idling once it put it in gear and it must idle under load.

 

[yorab]

Re: 1963 75hp Link & Sync Not Working

Thanks for the reply boldtr. Just what I love, an answer with a great explanation so that I can understand how the system works--not just how to set it. Kudos!