Post by bubbasz1 on Nov 18, 2009 20:35:57 GMT -5
Ran across this a while ago, figured I would pass the information on like a good boy.
Used on a variety of GM automobiles from 1952 to 1967, including the 1961 to 1963 Buick/Oldsmobile/Pontiac aluminum 215 V8's, the 4G was Rochester's first four barrel. Produced in 486, 553, and 692 CFM ratings, the 4G uses a squarebore layout with a conventional fixed jet, power valve and accelerator pump metering scheme. Secondaries are mechanically actuated but use an adjustable spring loaded air valve. Adjustment is achieved by loosening an allen head set screw and inserting a screwdriver. Rotating the screwdriver counterclockwise increases tension. The accelerator pump is also adjustable, using a link with 5 adjustment holes. Four center pivot floats are used. The 4G's used the small diameter 4-7/32" diameter air cleaner, shared by the first generation Carter AFB's, so the usual aftermarket air filter cases will not fit. However there are adapter rings and street rod sources usually carry compatible air filter cases. While the Rochester book mentioned in the reference section briefly covers the 4G, your best bet for information is a GM shop manual from the '50's or '60's.
Model /CFM Venturi Diameter/ Bore Diameter
primary secondary / primary secondary
4 Jet/ 486 1 1/8 1 1/4 / 1 7/16 1 7/16
4 Jet/ 553 1 1/8 1 15/32 / 1 7/16 1 11/16
4 Jet/ 692 1 1/8 1 15/32 / 1 9/16 1 11/16
Also a link to used 4 jets for sale from the carburetor shop, seems they always have a carb for the 442 for sale in their pile of used stuff.
www.thecarburetorshop.com/Carbsale.htm
This is what they should like when their pretty.
Used on a variety of GM automobiles from 1952 to 1967, including the 1961 to 1963 Buick/Oldsmobile/Pontiac aluminum 215 V8's, the 4G was Rochester's first four barrel. Produced in 486, 553, and 692 CFM ratings, the 4G uses a squarebore layout with a conventional fixed jet, power valve and accelerator pump metering scheme. Secondaries are mechanically actuated but use an adjustable spring loaded air valve. Adjustment is achieved by loosening an allen head set screw and inserting a screwdriver. Rotating the screwdriver counterclockwise increases tension. The accelerator pump is also adjustable, using a link with 5 adjustment holes. Four center pivot floats are used. The 4G's used the small diameter 4-7/32" diameter air cleaner, shared by the first generation Carter AFB's, so the usual aftermarket air filter cases will not fit. However there are adapter rings and street rod sources usually carry compatible air filter cases. While the Rochester book mentioned in the reference section briefly covers the 4G, your best bet for information is a GM shop manual from the '50's or '60's.
Model /CFM Venturi Diameter/ Bore Diameter
primary secondary / primary secondary
4 Jet/ 486 1 1/8 1 1/4 / 1 7/16 1 7/16
4 Jet/ 553 1 1/8 1 15/32 / 1 7/16 1 11/16
4 Jet/ 692 1 1/8 1 15/32 / 1 9/16 1 11/16
Also a link to used 4 jets for sale from the carburetor shop, seems they always have a carb for the 442 for sale in their pile of used stuff.
www.thecarburetorshop.com/Carbsale.htm
This is what they should like when their pretty.
