keep in mind that all technical information
given assumes our
parts are being used. Parts purchased from other sources may not
install, or work in a like manner.
How to Find The Carburetor Number?
The older Rochester 2G carburetors had a small triangular tag attached
to the top of the carburetor. Starting in 1968 the 2G carburetor had
the number stamped on the side of the float bowl below the inlet.
Pre 1968 2G carburtors cannot be identified without the tag. All other
numbers found on these carburetors are casting numbers and part numbers
that were used on multiple carburetor numbers.
Three Basic Types of Rochester 2 Jet
2G - Manual Choke
2GC - Automatic Choke
2GV - Divorced Choke (choke thermostat is mounted in the intake
Tri-Power - The center carbs used on 1958 Cadillac, 1958 Chevrolet,
1957 and 1958 Oldsmobile, and 1957 and 1958 Pontiac used front fuel
Be careful when removing the power
piston. The stem can break off easily and these are not longer being
produced. Push down on the stem and spring with your finger, then let
it snap back. Do this over and over until the piston comes out. A
frozen stem is another problem all together. Try spraying silicon spray
lubricant into the vent hole.
Hot Idle Compensator
Some Rochester 2g
carburetors had a hot idle compensator attached to
the middle of the venturi. When heated up, the bimetal bends up,
exposing a vent hole and allowing more air into the intake. This
compensated for an overheating condition on vehicle at idle, especially
air conditioned cars. Below is a picture of what the assembly will look
to Needle Clip
Most of the 2 jet kits will include a clip that attaches the float
needle to the float. This is used to facilitate lifting the needle out
of the seat allowing fuel to enter. Helpful when the needle wants to
stick. Watch closely how you install this clip so when done, the needle
is pulled straight up and down and not pulled to the side.
Watch a video about rebuilding this carburetor.
How to hard wire a 2GC choke to stay open. This only
works on a 2GC (intragal choke), not a 2GV.
Remove the hot air tube to the choke housing and cover the hold with a
piece of metal and use JB weld to keep it there. Remove the spring from
the thermostat and turn it around, then adjust the choke so that it
The 2G Rochester used a cast iron throttle body and it
is rare that they need to be re bushed because of free play. .005" to
.010" clearance is ok.