Which carburetor for 140 Mercruiser?

[thompson80]

I recently repowered from a 120 Mercruiser (1980 vintage) to a newer ('82-83) 140, built up from a remanufactured OMC long block. All the original components from the 120 Mercruiser were re-used, to make the 140 OMC into a 140 Mercruiser. But I notice different carburetors were used on the 120 and 140 Mercruisers of that era (part no. 1351-7354A1 for the 120 vs.1351-7355A1 for the 140). My original 120 carburetor is the Rochester 2GC, with the stovepipe choke. And I recently had the ports under the accelerator pump drilled up to deal with a hesitation issue from idle to about 1000-1200 RPM. That mod helped get rid of the majority of the hesitation, but there is still a very slight hesitation issue I'm hoping can be dealt with by performing a full tune up, new distributor cap, rotor, spark plug wires, timing. Both a new fuel pump filter & filter at the carb was recently installed, along with a fuel/water separator prior to the carb work. I'm also planning to toss the points and convert to a Perlux Ignitor & coil. My questions are: would I be better off, and/or, would I see any improvement in performance changing to the 140 version carburetor? What is/are the difference(s) between the two? Port and/or needle sizes?

 

[thompson80]

Since my original post I notice OMC and Mercruiser used different part numbers for their 2GC carbs. Anyone know what the differences are/were?