out of sync carbs

[1973z240]

when I get the carbs taking in the same amt of air even, i then test to do the same at 2000 rpm,

but i find that the back one takes in wayy much

and the front takes in about half of this.

how do i fix this?

do i turn the balancing screw?

i feel like the balancing screw is running out of track to turn and willl fall off.

[Mat M]

Do you have the original (to 1973) flat top carbs? Do the pistons slide easily, or does the front one stick a little?

[1973z240]

the carbs are 70's, they are round ones, not the flat.

the engine is 74

the car body is 73

the pistons are almost moving the same.

they are a tad off,

by like a couple millimeters.

[beandip]

If you balance the carbs at a 750 to 800 RPM and set the mixture then find the unbalance at 2K or so . If the vacuum pistons are free and sliding free. I would look to the springs that suppress the vacuum piston. they must be allowing the vacuum pistons to lift at the same rate to maintain the balance. If one of the electronic gurus could come up with a small camera that could watch the pistons rise and fall while driving to compare this . We could set them exactly. It's a possibility one of the springs have been stretched while cleaning or something . This would cause more pressure on the piston keeping it lower, or slower in lifting. I don't know if the springs are available at the Dealer or not but you could contact Steve at ZTherapy. Gary