a 4GC is a nice novelty, sort of a "blast from the past", but they suck like a Hoover upright vacuum cleaner where reliability and fuel economy are concerned. When Rochester decided to jump headfirst into the 4 barrel business in 1953 with the 4GC on the Buick, Cadillac, and Oldsmobile, my father was one of the few people in Nashville Tennessee who would work on them. The factory repair procedures didn't work, because of some severe design flaws. He spent so much time pestering the Rochester field engineer for the Nashville area that the family's little independent shop became an unofficial Rochester research facility. Some of the one-off modifications to the 4GC that he and Dad figured out to make those carbs work were standard on the 1954 production models.
There are two main sticking points to the 4GC- - - -float chamber size, and secondary air valve spring torque settings. With even a slightly too-low float setting, the 4GC empties the float bowls on full throttle acceleration, and the engines surges as the float chamber alternately fills and starves. There are two small air valves located brlow the secondary venturis with snail-shell springs resembling an automatic choke coil, only much smaller, holding them closed. The factory refused to provide the proper torque settings to adjust the spring tension, so if one got out of adjustment the technician was on his own as to where to set the springs.
In my opinion, a 4GC that's probably been worn out, rebuilt, and worn out again before it was 20 years old is probably a very poor choice for a new engine buildup unless you're building a numbers-correct concours show car. It will make a nice shelf decoration in the den, or a really good paperweight!
Jerry
