Early Carb 2.8L: ECM vs traditional/analog?

[pgtr]

In mid 1980s (84 for example) the 2.8L in passenger cars like the FBody came with an ECM, which took inputs from things like TPS, O2, etc. and controlled carb mixture and vac advance...

Essentially the same 2.8L was also available in trucks like the S10 WITHOUT an ECM, O2, TPS, M/C solenoid etc. It had a slightly simpler version of the same carb and the distributor's advance was controlled centrifugally and by vacuum.

Q: All other things being equal - how would these two variants compare in efficiency (mileage)?

[robertisaar]

the one with either:

a damn good carb tuner

or

an O2 sensor and mixture control solenoid that works perfectly.

[pgtr]

I could get 27mpg out of the Firebird from 84 up throu early 90s. For the last 5 or 8 years I've still been getting 25, sometimes 26mpg.

In the last year or so I've grown increasingly tired of dealing with the emissions sensors affecting the carb mixture and timing. So I'm contemplating putting in a freshly rebuilt VaraJet out of an S10 (thus losing the MC solenoid etc) and a distributor out of an S10 (thus losing the computer controlled advance but gaining vac and centrifugal advances).

Given a freshly rebuilt (now S10) carb/ignition on the same engine - could I regain the 25-27mpg I used to get?

[pgtr]

Ok I installed a 2se carb and vac distributor from an 84 s10 along with a trans lockup conversion kit.

It runs great. smooth etc.

Mileage stayed the same however at 23 to 24. Didn't get better or worse in that regard.