Rich dip between shifts (Holley 4160s)

[ArizonaGuy]

I have several of these 1850s and 80457s, and they all do the same thing: in between shifts (manual transmission) I get a big rich dip on the AFR gauge, and for just a split second the motor isn’t real happy about it. I’ve tried low float levels, different PVs, MABs, even tried an anti-pullover shooter. None of my bigger carburetors do this, it’s just the little ones. The only thing I haven’t yet tried is an open spacer (I use a four-hole to shake these things down).

What causes this?

[ArizonaGuy]

Oh, IAB doesn’t seem to have any bearing on it either. One calibration has .070s, another has .078s, and they both go stoopid fat when I push the clutch in. So I don’t think it’s idle/tslot circuit related.

[steve cowan]

My opinion is the smaller carb has a better signal and is more sensitive to throttle position changes as you go through your shifts.
The bigger carb would be a time/ lag kinda deal.

[ArizonaGuy]

My opinion is the smaller carb has a better signal and is more sensitive to throttle position changes as you go through your shifts.
The bigger carb would be a time/ lag kinda deal.

I’m kinda thinking the same thing. Just to see if it makes any difference I’ll put the big open spacer on it, see if it softens the hit to the venturi some.

[1972ho]

Do these carburetor have power valves.Each time you shift doesn’t the vacuum change for a few.