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?
yes
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.
its stumbles because your idle air bleed it to big, needs to be about .035"
With the big 64? jet it accelerates fine but idles very rich and doesnt have much top end but is smooth.
idle AFR is all idle mix screw and idle/low speed air bleed. if you close that bleed up and then adjust your mix screw you'll be good. the 64 is so rich that your actually losing power.