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Any time you’re feeding a common plenum, the ‘1.25 rule’ doesn’t apply.

That rule is based on one throttle plate per cylinder, no common plenum (Individual runners).
 
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The 38DG-series carburetors were OEM on European Ford Granadas. We’re only taking 2.5 liter and 3.0 liter engines, but they revved a bit higher than the 4.2 liter Jeep engines.

Seeing how the Jeep is all about the low rpm torque, I’d say that even the standard 330-cfm airflow rating from a 38DG-series Weber is suitable. Certainly enough for 150 hp.

Boring the venturies for higher airflow may help at 5500 rpms, but you’d lose some of the carburetor’s flexibility down low.
 

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But you do bring up a good point, I see where people talk about the Weber 38 flowing the same amount as the Holley, 390 CFM? But then some bring up the 3 inch vs 1.5 inch measure, in water? Or something?
2-bbl carbs and 4-bbl carbs are measured at different depression values. 1.5” for 4-bbls and 3.0” for 2-bbls.

The conversion factor is 1.414, so a Holley 390 cfm 4-bbl flows 551 cfm on the 2-bbl rating scale, or about double what a 32/36 Weber flows.

For comparison, you’ll see around 270 cfm for a Weber 32/36, and 330 cfm for the 38DG series. Obviously the 38 DG compares similarly to a Holley 350 cfm 2-bbl.
 
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