Tuning with an A/F gauge

[F-BIRD'88]

:Without knowing exactly what you did to the 1850 holley it is hard to say..e

Put the 1850 back to stock and try it.
Again the pcv valve is always a critical factor right in the area you are having a issue.
If you modded it to also tune around a missing pcv valve before , you know what to do.

Its great to hear you made progress on the 650 eddy carb set up.

I have used to good old 1850 holley on a good number of engines.. Never had much issues with them at all.
They seem to run good. I usually only hotrod tweek the secondary side ...
One I built with a Throttle plate from a 750 3310 for grins..
650+/-cfm) It worked good on a 396
I used the secondary metering plate #21 on that one too.
Sort of a frankenCarb using what we had It worked good.

[F-BIRD'88]

One thing about the 650avs style eddy carbs (especially in pairs) Dual Quad .. Is you can dial it n the secondary air doors on them to match the acceleration rate of heavy vehicles.. If you had a pair on the eddy rpm hi rise dual quad intake on a warmed up 351w or 347w stroker you'd like it. Don't discount the ford weiand tunnel ram..
It will make big torque on a warmed up street motor.
Trucks like big torque.