Throttle plates don't open?

[Ryan87LX]

1963 Mercury 850e

I did a compression test on the motor over the weekend, and I noticed something odd.

I put the throttle lever full forward, but the carb throttle plates didn't move.

Everything seems to be connected, and the levers on the engine worked and moved.

Do these plates open by vacuum by any chance, or do I have a bigger issue?

Thanks.

[sutor623]

Nah man, something is not engaging. Does the timing advance when you push the throttle?(distributor will turn) If it does then what you need to look for is if the throttle arm is touching the distributor housing. When the distributor turns, right above the upper carb there is an arm that will engage the carb butterfly plate. Otherwise there are springs on the underside of the carb that my have broken. Also, are you sure you are looking at the plates and not the choke cover? Sometimes people mistake the choke plate as a throttle plate.

[Ryan87LX]

Ah fudge. Yes, the distributor turns, and I saw the place where the throttle arms should touch the dizzy housing - there were obvious wear marks there, but they don't actually make contact. I ended up wedging open the throttle plates to do the test.

There must be something either loose/disconnected or missing. Time to look at the manual a little closer.

Thanks.

[sutor623]

Yeah man, no prob, I have the 650, the slightly smaller model. If you continue to have issues, send me a picture and we'll figure it out. They should only start to touch as the timing advances. There is a little metal piece that looks like a wishbone. This piece is the part that should make contact with the dizzy housing.

P.S. It IS normal for the timing to advance quite a ways as you push the throttle, before the butterfly valves will start to open.