Carb linkage adjustment for 1976 Mercury 500 50hp with thunderbolt ignition.

[Lammie]

I rebuilt the carburetors on this outboard. In doing so I noticed the connector that connects the two carbs together was broken. I ordered and installed a new one. Now I need to know the process of adjustment. The connector has a slot on the bottom that obviously is used to set a delay for the bottom carburetor. The bottom carb is operating at startup because the rpms at idle are 1755rpm. Where is the proper setting of the mounting screw in the adjustment slot of the connector and should the throttle of the bottom carb be manually held closed when making the adjustment.

 

[racerone]

Both carburetors should be closed at idle.----Bottom carburetor only feeds cylinder 3 and 4.----Top carburetor only feeds cylinder 1 and 2.-----No such thing as " delay for the bottom carburetor " on these motors..----Adjust so that both carburetors start opening at exactly the same time !!

 

[Lammie]

OK Thanks.

 

[jimmbo]

Don't go messing with the Linkage between the Carb and the Spark Timing, unless you do a Link and Sync, and find it out of adjustment. Just make sure both carbs are Closed(I think, both have a small Spring to ensure they are closed) at idle. If they are closed at Idle, and the Linkage between them is secure, they will open together when need be

 

[Lammie]

Thanks. I apparently was told incorrectly by a Mercury mechanic that carburetor #2 throttle should not start opening until 1800rpm if load idle is 800 RPM. Trying to achieve that was giving me headaches.

 

[jimmbo]

Thanks. I apparently was told incorrectly by a Mercury mechanic that carburetor #2 throttle should not start opening until 1800rpm if load idle is 800 RPM. Trying to achieve that was giving me headaches.

That Mechanic somehow thought you had a 4 cylinder 2+2 motor, those weird things were more than double the HP of yours