High Idle, throttle adjustment?

[Dassault]

I recently rebuilt my carbs and completed a lync and sync after installation. I made sure all of the butterflys were closed and checked timing etc. Now i am having idle issues, idling around 1000-1100 out of gear. I can lower it by adjusting the throttle cable and allowing the distributor to rotate further around, retarding timing. However if i get the idle where I want it, the butterflys do not open all of the way; throttle cable limited. How far open shoud the butterflys be, parallel to the carb walls? If they do need to be parallel, how can i lower my idle? Boat runs great, just need to lower the idle.

 

[usskydvr]

Re: High Idle, throttle adjustment?

Butterflys should be parallel to the carb wall. Disconnect the throttle cable from the engine and hold the linkage where it connects to the fully closed position. Adjust the timing and idle screws for correct idle. Reconnect the throttle cable. If that will not let you have both the same idle and correct WOT, then you have a cable or controller problem.

 

[Chris1956]

Re: High Idle, throttle adjustment?

OK, Sounds like you have an inline motor of the 70s vintage. The link and sync sets the idle timing to be at the spec, just as the carbs start to open. The throttle cable lowers the idle rpm to the correct speed, likely 900RPM.

As was stated, the controller should have plenty of travel to open the carbs all the way. Is the throttle stop set screw in the correct position?

 

[Dassault]

Re: High Idle, throttle adjustment?

Sorry you are correct, it is a 78 115hp. I have messed with the throttle stop (loosened completely) to see if it was cauing interference but it was not the cause. i will try the method described above this evening and see what happens.