ROCHESTER Triple 2-Barrel Carburetors: Description: Notes

One 2GC or 2GV (center) and two 2G (front and rear) carburetors are used, with the center carburetor having all conventional carburetor systems. The front and rear carburetors have only float, pump, and main metering systems. Throttle valves in front and rear carburetors are operated by a vacuum diaphragm mounted on front or rear carburetor and controlled by a vacuum switch on center carburetor. Front and rear carburetors are connected at throttle shafts so throttle valves and accelerating pumps operate simultaneously. On early synchro-mesh carburetors and all automatic transmission carburetors, provision is made to prevent operation of front and rear carburetors before normal engine operating temperature is reached; on some units a choke operated mechanical linkage is used, while on other carburetors a thermostatically operated vacuum valve at front of engine manifold in water jacket cuts off vacuum to center carburetor vacuum switch when engine cold. An idle compensator valve is used on some models to allow air to be drawn into carburetor bores under hot idling conditions.

CARBURETOR ADJUSTMENT SPECIFICATIONS

Rochester Carb. No.

Idle Speed @ (Eng. RPM)

Float

Choke Setting

Choke Rod ⁽¹⁾

Accel. Pump ⁽¹⁾

Idle Vent

Vacuum Switch ⁽¹⁾

Unloader ⁽¹⁾

Level ⁽¹⁾

Drop ⁽¹⁾

7013015

..........

1 5/16" ⁽⁴⁾

1 29/32"

.....

1 3/16"

..........

.....

7013016

450 ⁽⁷⁾

1 1/4" ⁽⁴⁾

1 29/32"

Index

.089"

1 3/16"

..........

1/32"

.360"

7013017

..........

1 5/16" ⁽⁴⁾

1 29/32"

.....

1 3/16"

..........

.....

7013020

475 ⁽⁷⁾

1 1/4" ⁽⁴⁾

1 29/32"

Index

.089"

1 3/16"

..........

1/32"

.360"

7013026

450 ⁽⁵⁾

1 1/4" ⁽⁴⁾

1 29/32"

Index

.089"

1 3/16"

..........

1/32"

.360"

7013033

..........

23/32" ⁽⁵⁾

1 29/32"

.....

7/8"

..........

.....

7013034

480

15/16" ⁽⁵⁾

1 29/32"

Index

.061"

1 3/16"

1 1/16"

1 5/32"

.163"

7013035

..........

23/32" ⁽⁵⁾

1 29/32"

.....

7/8"

..........

.....

7013037

480 ⁽⁶⁾

15/16" ⁽⁵⁾

1 29/32"

Index

.061"

1 3/16"

1 1/16"

1 5/32"

.163"

7013063

..........

23/32" ⁽⁵⁾

1 3/4"

.....

55/64"

..........

.....

7013064

480-500 ⁽⁸⁾

23/32" ⁽⁵⁾

1 3/4"

Index

.056"

1 3/16"

15/32"

1 5/32"

.163"

7013065

..........

23/32" ⁽⁵⁾

1 3/4"

.....

55/64"

..........

.....

7013067

480-500 ⁽⁸⁾

23/32" ⁽⁵⁾

1 3/4"

Index

.056"

1 3/16"

15/32"

1 5/32"

.163"

7013973

..........

1 13/32" ⁽⁴⁾

1 29/32"

.....

1 3/16"

..........

.....

7013974

475 ⁽⁵⁾

1 1/4" ⁽⁴⁾

1 29/32"

Index

.089"

1 3/16"

..........

1/32"

.360"

7013975

..........

1 13/32" ⁽⁴⁾

1 29/32"

.....

1 3/16"

..........

.....

7015066

480-500

23/32" ⁽⁵⁾

1 3/4"

Index

.056"

1 1/8"

1 1/32"

1 5/32"

.163"

7015068

480-500

23/32" ⁽⁵⁾

1 3/4"

Index

.056"

1 1/8"

1 1/32"

1 5/32"

.163"

7015076

480-500

23/32" ⁽⁵⁾

1 3/4"

Index

.056"

1 1/8"

1 1/32"

1 5/32"

.163"

7019064

480-500 ⁽⁸⁾

23/32" ⁽⁵⁾

1 3/4"

Index

.056"

1 1/8"

1 1/32"

1 3/32"

.163" ⁽⁹⁾

7019067

480-500 ⁽⁸⁾

23/32" ⁽⁵⁾

1 3/4"

Index

.056"

1 1/8"

1 1/32"

1 3/32"

.163" ⁽⁹⁾

7019069

480-500 ⁽⁸⁾

23/32" ⁽⁵⁾

1 3/4"

Index

.056"

1 1/8"

1 1/32"

.163 ⁽⁹⁾

7020064

480-500 ⁽⁸⁾

23/32" ⁽⁵⁾

1 3/4"

Index

.056"

1 1/8"

1 1/32"

.163 ⁽⁹⁾

7020067

480-500 ⁽⁸⁾

23/32" ⁽⁵⁾

1 3/4"

Index

.056"

1 1/8"

1 1/32"

.163 ⁽⁹⁾

7020069

480-500 ⁽⁸⁾

23/32" ⁽⁵⁾

1 3/4"

Index

.056"

1 1/8"

1 1/32"

.163 ⁽⁹⁾

7023073

480-500 ⁽⁸⁾

23/32" ⁽⁵⁾

1 3/4"

Index

.056"

1 1/8"

1 1/32"

.163 ⁽⁹⁾

7023075

480-500 ⁽⁸⁾

23/32" ⁽⁵⁾

1 3/4"

Index

.056"

1 1/8"

1 1/32"

.163" ⁽⁹⁾

7023077

480-500 ⁽⁸⁾

23/32" ⁽⁵⁾

1 3/4"

Index

.056"

1 1/8"

1 1/32"

.163" ⁽⁹⁾

7023078

..........

23/32" ⁽⁵⁾

1 3/4"

.....

55/64"

..........

.....

7023079

..........

23/32" ⁽⁵⁾

1 3/4"

.....

55/64"

..........

.....

7023161

640-660 ⁽¹⁰⁾

23/32" ⁽⁵⁾

1 3/4"

Index

.056"

1 1/8"

1 1/32"

.163" ⁽⁹⁾

7023162

640-660 ⁽¹⁰⁾

23/32" ⁽⁵⁾

1 3/4"

Index

.056"

1 1/8"

1 1/32"

.163" ⁽⁹⁾

7024074

640-660 ⁽¹⁰⁾

23/32" ⁽⁵⁾

1 3/4"

Index

.056"

1 1/8"

1 1/32"

⁽¹¹⁾

7024075

640-660 ⁽¹⁰⁾

23/32" ⁽⁵⁾

1 3/4"

Index

.056"

1 1/8"

1 1/32"

⁽¹¹⁾

7024078

..........

21/32"

1 3/4"

.....

27/32"

.....

7024079

..........

21/32"

1 3/4"

.....

27/32"

.....

7024173

480-500 ⁽⁸⁾

21/32" ⁽⁵⁾

1 3/4"

Index

.056"

1 1/8"

1 3/32"

⁽¹¹⁾

7024175

480-500 ⁽⁸⁾

21/32" ⁽⁵⁾

1 3/4"

Index

.056"

1 1/8"

1 3/32"

⁽¹¹⁾

7024178

..........

21/32" ⁽⁵⁾

1 3/4"

.....

27/32"

..........

.....

7024179

..........

21/32" ⁽⁵⁾

1 3/4"

.....

27/32"

..........

.....

7025070

⁽¹²⁾

11/16" ⁽⁵⁾

1 3/4"

Index

.055"

1 1/8"

1 3/32"

.160"

7025074

⁽¹²⁾

11/16" ⁽⁵⁾

1 3/4"

Index

.055"

1 1/8"

1 3/32"

.160"

7025075

580-600 ⁽³⁾

11/16" ⁽⁵⁾

1 3/4"

Index

.055"

1 1/8"

1 3/32"

..........

.160"

7025078

.....

21/32"

1 3/4"

.....

27/32"

.....

7025079

..........

21/32" ⁽⁵⁾

1 3/4"

.....

27/32"

.....

7025173

480-500 ⁽⁸⁾

11/16" ⁽⁵⁾

1 3/4"

Index

.055"

1 1/8"

1 3/32"

.160"

7025175

580-600 ⁽³⁾

11/16" ⁽⁵⁾

1 3/4"

Index

.055"

1 1/8"

1 3/32"

..........

.160"

7025177

580-600 ⁽³⁾

11/16" ⁽⁵⁾

1 3/4"

Index

.055"

1 1/8"

1 3/32"

..........

.160"

7025178

..........

21/32" ⁽⁵⁾

1 3/4"

.....

27/32"

..........

7025179

..........

21/32" ⁽⁵⁾

1 3/4"

.....

27/32"

..........

7026055

.....

3/4"

1 3/4"

.....

27/32"

..........

7026056

600

5/8"

1 3/4"

⁽¹⁶⁾

.100"

1 11/32"

1 9/32"

1 3/32"

.160"

7026057

.....

3/4"

1 3/4"

.....

27/32"

..........

7026074

⁽¹⁵⁾

19/32"

1 3/4"

⁽¹⁶⁾

.095"

1 21/64"

1 9/32"

1 3/32"

.160"

7026075

600 ⁽¹³⁾

19/32"

1 3/4"

⁽¹⁶⁾

.095"

1 21/64"

1 9/32"

1 3/32"

.160"

7036175

700 ⁽¹⁴⁾

19/32"

1 3/4"

⁽¹⁶⁾

.095"

1 21/64"

1 9/32"

1 3/32"

.160"

⁽¹⁾	See procedure below.

⁽²⁾	Auto. Trans. in "D" (Drive).

⁽³⁾	640-660 RPM with Air Cond. turned OFF.

⁽⁴⁾	"Vertical Seam" type.

⁽⁵⁾	"Horizontal Seam" type.

⁽⁶⁾	Air Conditioner turned ON.

⁽⁷⁾	Cars with Hydraulic Lifters only.

600 RPM with mechanical lifters.

⁽⁸⁾	540-560 RPM with Air Cond. turned OFF.

⁽⁹⁾	.143-.183" permissible.

⁽¹⁰⁾	690-710 RPM with Air Cond. turned OFF.

⁽¹¹⁾	.130-.190".

⁽¹²⁾	356 HP Eng . - 480-500 RPM (Without Air Cond.).

540-560 RPM (Air Cond. Cars with Air Cond. OFF).
376 HP Eng. - 580-600 RPM (Without Air Cond).
640-660 RPM (Air Cond. Cars with Air Cond. OFF).

⁽¹³⁾	700 RPM on Air Conditioned Cars (Air Cond. OFF).

⁽¹⁴⁾	Air Conditioning OFF (when used).

⁽¹⁵⁾	Pontiac 421" V8 - 500 RPM (575 RPM on Air Conditioned Cars with Air Cond. OFF).

Pontiac 421" HO V8 - Same as Tempest.
Tempest - 600 RPM (675 RPM on Air Conditioned Cars with Air Cond. OFF).

⁽¹⁶⁾	See text for adjustment procedure.

NOTE: 1965 & Later Pontiac & Tempest Cars (with Synchro-mesh Trans.) have new design mechanical linkage (no vacuum switch) as follows: