mercury 500 carburetor float setting

[poortenga]

I'm trying to set my carburetor float on my 1976 Mercury 500 carbs. The float needles have springs. The float levels were set at 1/4" when the float was manually depressed to where there is no more "spring" but the float level is twice as high when the float is resting with just it's own weight against the float needle/spring. I'm thinking this was done incorrectly by PO and the setting should be set at 1/4" when the float is simply sitting with it's own weight resting against the spring. The service manual doesn't comment on this spring phenomenon. Can anyone advise on the appropriate way to deal with this? Thanks.

 

[GA_Boater]

What's the serial number? I used serial number 4357640 - 5531629 range for 1976 and no spring on the needles.

 

[poortenga]

The part number for the needle is 18-7295 - Needle Valve
It has a spring installed right on it and the spring does not have a separate number. Both the old needle valves and the new ones I ordered with my serial number
(4360375) have the spring integral to the needle. It doesn't show on the diagram but when you look at the actual part, it has the spring.
I'm thinking it would be best to set the float level without compressing the spring at all but I am hoping someone can confirm that for me.
Thanks

 

[GA_Boater]

Looked at another diagram and the spring is shown. The float adjustment steps from my manual are;

Float Level Adjustment.

Turn the carb upside down and set the float to 1/4" +- 1/64" with the float sitting on it's own weight. The 1/4" is from the carb body to the bottom edge (facing up) of the float. Carefully adjust the needle actuating arm for 1/4"​

Float Drop Adjustment.

Turn the carb right-side up and set the float drop to 1/64" to 1/32" from the bottom of the float to the Main Fuel Jet. Adjust the float tang carefully to get the 1/64-1/32" drop.​

So your thoughts are correct. Don't push the float against the spring.

 

[poortenga]

Thanks. That makes way more sense than the way it was set. Surprisingly, it started and idled great when I bought it but I suppose the float level wouldn't really affect idling much. I rebuilt the carbs because one was leaking. I'm sure it would probably have run very poorly at high end with how things were set. Now I just need to wait for spring.