Looking for a little advice on the timing numbers I just pulled from my 73’ Duster (backfire issue)
Choke is fully open your first photo.
For the idle mix adjustment to be effective, the primary side throttle blades need to be positioned so only a bit of the transfer slots are exposed below the plate.
Soooo, if you've adjusted idle speed up (or down) with the 'idle speed screw' what you've actually done is open or close the throttle position for idle. That's fine, but there's a limited range of adjsutment before too much or too little trasnfer slot is showing below the blade. If the transfer slot is too exposed then the idle port doesn't do much.
PS. 'Idle circuit' is a misnomer. Better to think of it as the low speed or low throttle circuit.
This illustrates how both the transfer slot and the idle port contribute fuel mixture at idle.
Choke is fully open your first photo.
For idle mixture - yes.
For the idle mix adjustment to be effective, the primary side throttle blades need to be positioned so only a bit of the transfer slots are exposed below the plate.
Soooo, if you've adjusted idle speed up (or down) with the 'idle speed screw' what you've actually done is open or close the throttle position for idle. That's fine, but there's a limited range of adjsutment before too much or too little trasnfer slot is showing below the blade. If the transfer slot is too exposed then the idle port doesn't do much.
PS. 'Idle circuit' is a misnomer. Better to think of it as the low speed or low throttle circuit.
This illustrates how both the transfer slot and the idle port contribute fuel mixture at idle.