Holley 1920 Metering Blocks?

I have what looks like an early Holley 1920 I found at the junkyard with the float, bowl cover and a few linkages missing. I replaced all of those but one of the check balls and the brass ring around it were missing from the metering block. I found a stripped down 1920 at another yard and put that metering block in my carb. Both carbs were early models on different 64 Darts so I figured they might work about the same.

I guess my question is...Can you swap Holley 1920 metering blocks if they're off of similar carbs on similar cars?



The carb I'm using had a big main metering jet, with the number 641 stamped on it. The one in the block I swapped in is a number 57. With the 57 jet, it stumbles on acceleration and fades in and out but has power. With the big 64? jet it accelerates fine but idles very rich and doesnt have much top end but is smooth.

Should I continue to mess with the jetting, or is swapping metering blocks a bad idea in general? I did replace the accel. pump and gaskets so I dont think its leaking anywhere.