Float Toe (Floats with Dimple at Toe End)

With air horn inverted and air horn gasket in place, measure distance from gasket surface to center of dimple at float toe. Distance should be as specified in table. To adjust, bend float as shown in illustration.

NOTE: Always check Float Level (Heel) if Toe adjustment is required.

Fig 1: FLOAT TOE ADJUSTMENT (WEDGE SHAPED METAL FLOATS WITH DIMPLE)

Courtesy of GENERAL MOTORS COMPANY

ROCHESTER 4GC 4-BARREL CARBURETOR ADJUSTMENT SPECIFICATIONS (Table No. 1)

Rochester Carb. No.

Hot Idle Speed (Engine RPM)

Fast Idle Eng. RPM

Float Level Setting

Float Drop Setting

Float Toe Setting

S.M. Trans.

Auto. Trans. ⁽¹⁷⁾

Pri.

Sec.

Pri.

Sec.

Pri.

Sec.

7011108

475 ⁽¹⁾

425 ⁽¹⁾

⁽⁴⁾

1 5/8"

1 11/16"

2 1/4"

..........

7011570

485 ⁽¹⁾

485 ⁽¹⁾⁽²⁾

1500 ⁽⁸⁾

1 3/8"

1 13/16"

⁽⁵⁾

7011600

..........

485 ⁽²⁾⁽³⁾

1500 ⁽⁸⁾

1 3/8"

1 5/16"

3/8"

7011701

450-470

480-500 ⁽¹⁰⁾

2700 ⁽⁸⁾

1 15/32"

1 3/8"

1 1/2"

1 5/16"

11/16"

3/8"

7012000

..........

420 ⁽¹⁹⁾

1700 ⁽²¹⁾

1 3/8"

1 13/16"

⁽⁵⁾

7012001

..........

420 ⁽¹⁾⁽¹⁹⁾

1700 ⁽²¹⁾

1 3/8"

1 13/16"

⁽⁵⁾

7012010

..........

450 ⁽⁷⁾

1700 ⁽²⁾⁽²¹⁾

1 3/8"

1 5/16"

3/8"

7012011

..........

450 ⁽⁷⁾

1700 ⁽²⁾⁽²¹⁾

1 3/8"

1 5/16"

3/8"

7012126

450 ⁽¹⁾

425 ⁽¹⁾

⁽⁴⁾

1 5/8"

2 1/4"

.......

7012128

475 ⁽¹⁾

425 ⁽¹⁾

⁽⁴⁾

1 5/8"

1 11/16"

2 1/4"

......

7012400

..........

450 ⁽⁹⁾

1500 ⁽⁸⁾

1 15/32"

1 3/8"

1 1/2"

1 5/16"

11/16"

3/8"

7012401

460 ⁽⁹⁾

..........

1500 ⁽⁸⁾

1 15/32"

1 3/8"

1 1/2"

1 5/16"

11/16"

3/8"

7012811

450

450 ⁽⁷⁾

1700 ⁽²⁾⁽²¹⁾

1 7/16"

1 3/8"

1 1/2"

1 5/16"

5/8"

3/8"

7012910

..........

450

1700 ⁽²⁾⁽²¹⁾

1 7/16"

1 3/8"

1 1/2"

1 5/16"

5/8"

3/8"

7013004

475

450

⁽⁴⁾

1 5/8" ⁽¹²⁾

1 11/16"⁽¹²⁾

2 1/4"

......

7013006

475

450

⁽⁴⁾

1 5/8" ⁽¹²⁾

1 11/16"⁽¹²⁾

2 1/4"

......

7013010

475 ⁽⁷⁾

450 ⁽⁷⁾

⁽⁴⁾

1 5/8" ⁽¹²⁾

1 11/16"⁽¹²⁾

2 1/4"

......

7013012

475 ⁽⁷⁾

450 ⁽⁷⁾

⁽⁴⁾

1 5/8" ⁽¹²⁾

1 11/16"⁽¹²⁾

2 1/4"

......

7013030

..........

480

1700-1750⁽⁸⁾

1 7/16"

1 3/8"

1 1/2"

1 5/16"

5/8"

3/8"

7013031

..........

480 ⁽¹⁾

1700-1750⁽⁸⁾

1 7/16"

1 3/8"

1 1/2"

1 5/16"

5/8"

3/8"

7013044

..........

485 ⁽²⁾⁽³⁾

1500 ⁽⁸⁾

⁽²⁰⁾

1 3/8"

1 1/2"⁽¹¹⁾

1 5/16"

11/16"⁽¹⁵⁾

3/8"

7013050

460

1600 ⁽⁸⁾

1 15/32"

1 3/8"

1 1/2"

1 5/16"

11/16"

3/8"

7013100

..........

485 ⁽²⁾⁽³⁾

1500 ⁽⁸⁾

1 13/32"

1 3/8"

1 11/32"

7/16"

3/8"

7013150

460 ⁽¹⁴⁾

520 ⁽¹⁵⁾

1600 ⁽⁸⁾

1 5/32"

1 3/8"

1 1/2"

1 5/16"

11/16"

3/8"

7013950

460

1600 ⁽⁸⁾

1 5/32"

1 3/8"

1 1/2"

1 5/16"

11/16"

3/8"

7013952

460 ⁽¹⁴⁾

520 ⁽¹⁵⁾

1600 ⁽⁸⁾

1 5/32"

1 3/8"

1 1/2"

1 5/16"

11/16"

3/8"

7015004

475

450

⁽⁴⁾

1 17/32"⁽¹³⁾

1 19/32"⁽¹³⁾

2 1/4"

......

7015006

475

450

⁽⁴⁾

1 17/32"⁽¹³⁾

1 19/32"⁽¹³⁾

2 1/4"

......

7015010

475 ⁽¹⁾

450 ⁽¹⁾

⁽⁴⁾

1 17/32"⁽¹³⁾

1 19/32"⁽¹³⁾

2 1/4"

......

7015012

475 ⁽¹⁾

450 ⁽¹⁾

⁽⁴⁾

1 17/32"⁽¹³⁾

1 19/32"⁽¹³⁾

2 1/4"

......

7015040

..........

485 ⁽²⁾⁽³⁾

1500⁽⁸⁾

1 11/32"

1 3/8"

1 7/16"

1 5/16"

9/16"

3/8"

7019004

475

450

⁽⁴⁾

1 33/64"

1 37/64"

2 1/4"

......

7019006

475

⁽⁴⁾

1 33/64"

1 37/64"

2 1/4"

......

7019010

475 ⁽¹⁾

450 ⁽¹⁾

⁽⁴⁾

1 33/64"

1 37/64"

2 1/4"

......

7019014

475

450

⁽⁴⁾

1 33/64"

1 37/64"

2 1/4"

......

7019030

..........

450-480

1700 ⁽⁸⁾

1 7/16"

1 3/8"

1 1/2"

1 5/16"

5/8"

3/8"

7019031

..........

450-480 ⁽¹⁾

1700 ⁽⁸⁾

1 7/16"

1 3/8"

1 1/2"

1 5/16"

5/8"

3/8"

7019040

525 ⁽¹⁶⁾

525 ⁽²⁾⁽¹⁶⁾

650 ⁽⁶⁾

1 11/32"

1 3/8"

1 7/16"

1 5/16"

9/16"

3/8"

7019050

550

500

1600 ⁽⁸⁾

1 15/32"

1 3/8"

1 1/2"

1 5/16"

11/16"

3/8"

7019054

550 ⁽¹⁴⁾

500 ⁽¹⁴⁾

1600 ⁽⁸⁾

1 15/32"

1 3/8"

1 1/2"

1 5/16"

11/16"

3/8"

7019055

550

500

1900 ⁽⁸⁾

1 13/32"

1 3/8"

1 1/2"

1 3/8"

5/8"

3/8"

7019056

550

1900 ⁽⁸⁾

1 13/32"

1 3/8"

1 1/2"

1 3/8"

5/8"

3/8"

7019066

680-700 ⁽⁷⁾

580-600 ⁽¹⁸⁾

3000 ⁽⁸⁾

1 21/64"

1 1/4"

9/16"

7019079

680-700

580-600

2800 ⁽⁸⁾

1 21/64"

1 1/4"

9/16"

7020006

500

475

⁽⁴⁾

1 33/64"

1 37/64"

2 1/4"

......

7020012

500

475

⁽⁴⁾

1 33/64"

1 37/64"

2 1/4"

......

7020022

500

475

⁽⁴⁾

1 33/64"

1 37/64"

2 1/4"

......

7020023

500

..........

⁽⁴⁾

1 1/2"

1 5/16"

1 1/2"

1 1/8"

13/16"

1/2"

7020024

..........

475

⁽⁴⁾

1 1/2"

1 5/16"

1 1/2"

1 1/8"

13/16"

1/2"

7020040

525

525 ⁽²⁾⁽¹⁶⁾

625 ⁽⁶⁾

1 11/32"

1 3/8"

1 7/16"

1 5/16"

9/16"

3/8"

7020041

525

525 ⁽²⁾⁽³⁾

625 ⁽⁶⁾

1 11/32"

1 3/8"

1 7/16"

1 5/16"

9/16"

3/8"

7020043

..........

525 ⁽²⁾⁽¹⁷⁾

650 ⁽⁶⁾⁽¹⁸⁾

1 11/32"

1 3/8"

1 7/16"

1 5/16"

9/16"

3/8"

7020045

525 ⁽¹⁷⁾

..........

650 ⁽⁶⁾⁽¹⁸⁾

1 11/32"

1 3/8"

1 7/16"

1 5/16"

9/16"

3/8"

7020066

..........

580-600 ⁽¹⁸⁾

3000 ⁽⁸⁾

1 21/64"

1 1/4"

9/16"

7020078

580-600

580-600 ⁽⁷⁾

2800 ⁽⁸⁾

1 11/32"

1 3/8"

1 7/16"

1 5/16"

9/16"

3/8"

7020079

680-700⁽⁷⁾

..........

2800 ⁽⁸⁾

1 21/64"

1 1/4"

9/16"

7020950

550

475

1600 ⁽⁸⁾

1 15/32"

1 3/8"

1 1/2"

1 5/16"

11/16"

3/8"

7020952

550

475

1800 ⁽⁸⁾

1 13/32"

1 3/8"

1 1/2"

1 3/8"

5/8"

3/8"

⁽¹⁾	Air Conditioning ON.

⁽²⁾	Transmission in NEUTRAL or PARK.

⁽³⁾	550 RPM with Air Conditioning.

⁽⁴⁾	No Adjustment. Fast idle will be correct when slow idle correctly set.

⁽⁵⁾	Flush with gasket surface of air horn.

⁽⁶⁾	Fast idle screw on low step of fast idle cam.

(7) - No idle speed specified. Set idle as low as possible in DRIVE for smooth idling and to prevent creep or harsh

⁽⁷⁾	Air Conditioning OFF.

⁽⁸⁾	Fast idle screw on high step of fast idle cam.

(10) - 500 RPM with modified carburetor.

⁽⁹⁾	520 RPM with maximum air conditioner load.

⁽¹⁰⁾	540-560 RPM with air conditioning OFF.

⁽¹¹⁾	With vacuum assist. I 7/16" without vacuum assist.

⁽¹²⁾	Without float torsion spring on primary floats.

⁽¹³⁾	With float torsion spring on primary floats.

⁽¹⁴⁾	Air Conditioning OFF if equipped with idle compensator; ON if no idle compensator.

⁽¹⁵⁾	1/2" without vacuum assist spring.

⁽¹⁶⁾	575 RPM with Air Conditioning OFF.

⁽¹⁷⁾	Transmission in DRIVE except as noted.

⁽¹⁸⁾	630-650 RPM with Air Conditioning OFF.

⁽¹⁹⁾	520 RPM with two carburetors.

(22) - Fast idle screw on second highest step of fast idle cam against shoulder of top step.
(23) - 525 with Air Conditioning OFF.

⁽²⁰⁾	3/8" without vacuum assist, I 15/32" with vacuum assist.

(25) - 600 RPM with Air Conditioning OFF.
(26) - 283" Engine only. For 327" Engine: 475-500 RPM (Synchro-mesh), 450-475 RPM (Auto. Trans.).
(27) - Index for Turboglide.
(28) - 500-520 with Air Conditioning ON.

⁽²¹⁾	With fast idle screw on high step of fast idle cam, Air Conditioning ON. 2000 RPM with two carburetors.

(30) - 550 RPM (Air Cond. Cars) Air Cond. OFF.

ROCHESTER 4GC 4-BARREL CARBURETOR ADJUSTMENT SPECIFICATIONS (Table No. 2)

Rochester Carb. No.

Vacuum Assist Setting

Pump Rod Setting

Pump Rod Position

Idle Vent Setting

Choke Rod Setting

Initial Fast Idle Setting

Auto. Choke Setting

Unloader Setting

7011108

..........

1 1/16"

........

.043"

.....

1 Lean ⁽¹⁾

.235"

7011570

..........

1 1/64"

Outer

........

.148"

.024"

Index

.128"

7011600

..........

1 1/32"

Center

........

.148"

.028"

Index

.128"

7011701

1 1/16"

15/16"

........

7/8"

.063"

.033"

Index

.115"

7012000

..........

15/16"

........

7/8"

.040"

.020"

Index

.125"

7012001

..........

15/16"

........

7/8"

.040"

.020"

Index

.125"

7012010

..........

29/32"

........

13/16"

.040"

.020"

Index

.125"

7012011

..........

29/32"

........

13/16"

.040"

.020"

Index

.125"

7012126

..........

1 1/16"

........

.......

.043"

........

1 Lean

.235"

7012128

..........

1 1/16"

........

.043"

........

1 Lean ⁽¹⁾

.235"

7012400

1 5/32"

1 1/32"

........

29/32"

.052"

.024"

........

.115"

7012401

1 5/32"

1 1/32"

........

29/32"

.052"

.024"

........

.115"

7012811

1 1/32"

29/32"

........

13/16"

.040"

.020"

Index

.125"

7012910

1 1/32"

29/32"

........

13/16"

.040"

.020"

Index

.125"

7013004

..........

1 1/16"

........

31/32"

.043"

........

1 Lean

.235"

7013006

..........

1 1/16"

........

31/32"

.043"

......

Index

.235"

7013010

..........

1 1/16"

........

31/32"

.043"

......

1 Lean

.235"

7013012

..........

1 1/16"

........

31/32"

.043"

.....

Index

.235"

7013030

1 3/32"

27/32"

........

3/4"

.040"

.024"

Index

.130"

7013031

1 3/32"

27/32"

........

3/4"

.040"

.024"

Index

.130"

7013044

1 1/16"

1 1/32"

Center

.......

.148"

.028"

Index

.128"

7013050

1 1/16"

1 1/32"

Inner

29/32"

.052"

.024"

Index

.115"

7013100

..........

1 1/32"

Center

........

.148"

.028"

Index

.128"

7013150

1 1/16"

1 1/32"

Inner

29/32"

.052"

.024"

Index

.115"

7013950

1 1/16"

1 1/32"

Inner

29/32"

.052"

.024"

Index

.115"

7013952

1 1/16"

1 1/32"

Inner

29/32"

.052"

.024"

Index

.115"

7015004

..........

1 1/16"

........

31/32"

.055"

......

1 Lean

.235"

7015006

..........

1 1/16"

........

31/32"

.055"

......

Index

.235"

7015010

..........

1 1/16"

........

31/32"

.055"

......

Index

.235"

7015012

..........

1 1/16"

........

31/32"

.055"

......

Index

.235"

7015040

..........

1 1/32"

Center

........

.060"

.028"

Index

.128"

7019004

..........

1 1/16"

........

31/32"

.055"

......

Index

.235"

7019006

..........

1 1/16"

........

31/32"

.055"

......

Index

.235"

7019010

..........

1 1/16"

........

31/32"

.055"

......

Index

.235"

7019014

..........

1 1/16"

........

31/32"

.055"

......

Index

.235"

7019030

1 3/32"

27/32"

........

3/4"

.040"

.024"

1 Rich

.125"

7019031

1 3/32"

27/32"

........

3/4"

.040"

.024"

1 Rich

.125"

7019040

..........

1 1/32"

Center

........

.060"

.028"

Index

.128"

7019050

1 1/16"

1 1/32"

Inner

29/32"

.050"

.024"

Index

.115"

7019054

1 1/16"

1 1/32"

Inner

29/32"

.050"

.024"

Index

.115"

7019055

29/32"

1 1/32"

Outer

15/16"

.050"

.024"

Index

.190"

7019056

29/32"

1 1/32"

Outer

15/16"

.050"

.024"

Index

.190"

7019066

..........

15/16"

Inner

55/64"

.030"

.028"

2 Rich

.152"

7019079

..........

15/16"

Inner

55/64"

.030"

.028"

1 Rich

.152"

7020006

..........

1 1/16"

........

31/32"

.055"

......

Index

.230"

7020012

..........

1 1/16"

........

31/32"

.055"

......

Index

.230"

7020022

..........

1 1/16"

........

31/32"

.055"

......

Index

.230"

7020023

1 7/32"

Outer

29/32"

.070"

......

Index

.130"

7020024

1 7/32"

Outer

29/32"

.070"

......

Index

.130"

7020040

..........

1 1/32"

Center

........

.060"

.028"

Index

.128"

7020041

..........

1 1/32"

Center

........

.060"

.028"

Index

.128"

7020043

..........

29/32"

Outer

........

.045"

.032"

Index

.128"

7020045

..........

29/32"

Outer

..........

.045"

.032"

Index

.128"

7020066

..........

15/16"

Inner

53/64"

.028"

1 Rich

.152"

7020078

..........

29/32"

Outer

........

.045"

.032"

Index

.130"

7020079

..........

15/16"

Inner

55/64"

.028"

1 Rich

.152"

7020950

1 1/16"

1 1/64"

Inner

29/32"

.052"

.024"

Index

.120"

7020952

29/32"

1 1/64"

Outer

15/16"

.052"

.024"

1 Rich

.190

(1) - Air Conditioning ON.
(2) - Transmission in NEUTRAL or PARK.
(3) - 550 RPM with Air Conditioning.
(4) - No Adjustment. Fast idle will be correct when slow idle correctly set.
(5) - Flush with gasket surface of air horn.
(6) - Fast idle screw on low step of fast idle cam.
(7) - No idle speed specified. Set idle as low as possible in DRIVE for smooth idling and to prevent creep or harsh
(8) - Air Conditioning OFF.
(9) - Fast idle screw on high step of fast idle cam.
(10) - 500 RPM with modified carburetor.
(11) - 520 RPM with maximum air conditioner load.
(12) - 540-560 RPM with air conditioning OFF.
(13) - With vacuum assist. I 7/16" without vacuum assist.
(14) - Without float torsion spring on primary floats.
(15) - With float torsion spring on primary floats.
(16) - Air Conditioning OFF if equipped with idle compensator; ON if no idle compensator.
(17) - 1/2" without vacuum assist spring.
(18) - 575 RPM with Air Conditioning OFF.
(19) - Transmission in DRIVE except as noted.
(20) - 630-650 RPM with Air Conditioning OFF.
(21) - 520 RPM with two carburetors.
(22) - Fast idle screw on second highest step of fast idle cam against shoulder of top step.
(23) - 525 with Air Conditioning OFF.
(24) - 3/8" without vacuum assist, I 15/32" with vacuum assist.
(25) - 600 RPM with Air Conditioning OFF.
(26) - 283" Engine only. For 327" Engine: 475-500 RPM (Synchro-mesh), 450-475 RPM (Auto. Trans.).

⁽¹⁾	Index for Turboglide.

(28) - 500-520 with Air Conditioning ON.
(29) - With fast idle screw on high step of fast idle cam, Air Conditioning ON. 2000 RPM with two carburetors.
(30) - 550 RPM (Air Cond. Cars) Air Cond. OFF.

ROCHESTER 4GC 4-BARREL CARBURETOR ADJUSTMENT SPECIFICATIONS (Table No. 1)

Rochester Carb. No.

Hot Idle Speed (Engine RPM)

Fast Idle Eng. RPM

Float Level Setting

Float Drop Setting

Float Toe Setting

S.M. Trans.

Auto. Trans. ⁽⁹⁾

Pri.

Sec.

Pri.

Sec.

Pri.

Sec.

7020953

550 ⁽⁷⁾

475 ⁽³⁾⁽⁷⁾

1800 ⁽⁸⁾

1 13/32"

1 3/8"

1 1/2"

1 3/8"

5/8"

3/8"

7020955

550 ⁽⁷⁾

500 ⁽³⁾⁽⁷⁾

1600 ⁽⁸⁾

1 15/32"

1 3/8"

1 1/2"

1 5/16"

11/16"

3/8"

7020985

550 ⁽⁷⁾

500 ⁽³⁾⁽⁷⁾

1800 ⁽⁸⁾

1 15/32"

1 3/8"

1 1/2"

1 1/8"

11/16"

3/8"

7022752

550 ⁽⁷⁾

500 ⁽³⁾⁽⁷⁾

1800 ⁽⁸⁾

1 15/32"

1 3/8"

1 1/2"

1 1/8"

11/16"

3/8"

7023006

475

450

⁽⁴⁾

1 17/32"

1 19/32"

2 1/4"

..........

7023012

475

450

⁽⁴⁾

1 17/32"

1 19/32"

2 1/4"

..........

7023030

..........

480

1700-1750 ⁽¹⁰⁾

1 7/16"

1 3/8"

1 1/2"

1 1/4"

5/8"

3/8"

7023031

..........

480

1700-1750 ⁽¹⁰⁾

1 7/16"

1 3/8"

1 1/2"

1 1/4"

5/8"

3/8"

7023040

475 ⁽¹¹⁾

625 ⁽⁵⁾

1 11/32"

1 3/8"

1 7/16"

1 1/4"

9/16"

3/8"

7023044

..........

500 ⁽³⁾

625 ⁽⁵⁾

1 11/32"

1 3/8"

1 9/16"

1 9/32"

9/16"

3/8"

7023045

500⁽¹⁾

..........

625⁽¹⁾

1 11/32"

1 3/8"

1 9/16"

1 9/32"

9/16"

3/8"

7023050

550

500

1600 ⁽⁸⁾

1 15/32"

1 3/8"

1 1/2"

1 3/16"

11/16"

3/8"

7023051

550 ⁽⁷⁾

500 ⁽²⁾⁽⁷⁾

1600 ⁽⁸⁾

1 15/32"

1 3/8"

1 1/2"

1 3/16"

11/16"

3/8"

7023054

..........

500 ⁽³⁾

1500 ⁽¹⁰⁾

1 7/16"

1 3/8"

1 1/8"

17/32"

3/8"

7023055

550 ⁽⁷⁾

..........

2400 ⁽⁸⁾

1 7/16"

1 3/8"

1 1/8"

17/32"

3/8"

7023069

680-700 ⁽⁷⁾

..........

2800 ⁽⁸⁾

1 11/32"

1 1/4"

9/16"

7023070

..........

580-600 ⁽⁷⁾

3000 ⁽⁸⁾

1 11/32"

1 1/4"

9/16"

7023143

475 ⁽¹¹⁾

450 ⁽⁴⁾

625 ⁽⁵⁾

1 11/32"

1 3/8"

1 7/16"

1 1/4"

9/16"

3/8"

7024030

..........

480

1700-1750 ⁽¹⁰⁾

1 7/16"

1 3/8"

1 1/2"

1 1/16"

5/8"

3/8"

7024031

..........

480

1700-1750 ⁽¹⁰⁾

1 7/16"

1 3/8"

1 1/2"

1 1/16"

5/8"

3/8"

7024040

500

500 ⁽³⁾

600 ⁽⁵⁾

1 11/32"

1 3/8"

1 7/16"

1 3/16"

17/32"

13/32"

7024044

550 ⁽¹⁰⁾

550 ⁽¹²⁾

600 ⁽⁵⁾

1 11/32"

1 3/8"

1 19/32"

1 3/16"

19/32"

3/8"

7024045

550 ⁽¹⁰⁾

550 ⁽¹²⁾

600 ⁽⁵⁾

1 11/32"

1 3/8"

1 19/32"

1 3/16"

19/32"

3/8"

7024050

500

1000 ⁽⁵⁾

1 15/32"

1 3/8"

1 3/16"

11/16"

3/8"

7024051

500

1000 ⁽⁵⁾

1 15/32"

1 3/8"

1 3/16"

11/16"

3/8"

7024054

600

..........

1000 ⁽⁵⁾

1 15/32"

1 3/8"

1 1/2"

1 1/8"

17/32"

3/8"

7024055

..........

500

1000 ⁽⁵⁾

1 15/32"

1 3/8"

1 1/2"

1 1/8"

17/32"

3/8"

7024120

..........

500

⁽⁴⁾

1 33/64"

1 37/64"

2 1/4"

..........

7024121

475-500

450-475

⁽⁴⁾

1 33/64"

1 37/64"

2 1/4"

..........

7024122

500 ⁽¹³⁾

⁽⁴⁾

1 33/64"

1 37/64"

2 1/4"

..........

7024123

500

..........

⁽⁴⁾

1 1/2"

1 5/16"

1 1/2"

1 1/8"

13/16"

1/2"

7024124

..........

500

⁽⁴⁾

1 1/2"

1 5/16"

1 1/2"

1 1/8"

13/16"

1/2"

7024125

500

..........

⁽⁴⁾

1 33/64"

1 37/64"

2 1/4"

..........

7024126

..........

500

⁽⁴⁾

1 33/64"

1 37/64"

2 1/4"

..........

7024127

500

..........

⁽⁴⁾

1 1/2"

1 13/32"

1 1/2"

1 7/16"

25/32"

21/32"

7024128

..........

500

⁽⁴⁾

1 1/2"

1 13/32"

1 1/2"

1 7/16"

25/32"

21/32"

7024153

500

1000 ⁽⁵⁾

1 15/32"

1 3/8"

1 1/2"

1 3/16"

11/16"

3/8"

7024154

500

1000 ⁽⁵⁾

1 15/32"

1 3/8"

1 1/2"

1 3/16"

11/16"

3/8"

7024220

..........

500

⁽⁴⁾

1 33/64"

1 37/64"

2 1/4"

..........

7024225

500

..........

⁽⁴⁾

1 33/64"

1 37/64"

2 1/4"

..........

7024226

..........

500

⁽⁴⁾

1 33/64"

1 37/64"

2 1/4"

..........

7025030

..........

480 ⁽¹⁾

1700-1750 ⁽⁸⁾

1 7/16"

1 3/8"

1 1/2"

1 1/16"

5/8"

3/8"

7025031

..........

480 ⁽¹⁾

1700-1750 ⁽⁸⁾

1 7/16"

1 3/8"

1 1/2"

1 1/16"

5/8"

3/8"

7025040

..........

500 ⁽³⁾

600 ⁽⁵⁾

1 13/32"

1 1/16"

1 1/4"

..........

7025042

..........

500 ⁽³⁾

600 ⁽⁵⁾

1 13/32"

1 1/16"

1 1/4"

..........

7025050

550

500

1000 ⁽⁵⁾

1 15/52"

1 3/8"

1 1/2"

1 9/32"

3/4"

3/8"

7025051

600 ⁽⁷⁾

550 ⁽⁷⁾

1000 ⁽⁵⁾

1 15/32"

1 3/8"

1 1/2"

1 9/32"

5/8"

3/8"

7025054

..........

500

1000 ⁽⁵⁾

1 7/16"

1 1/4"

..........

7025055

550

..........

1000 ⁽⁵⁾

1 7/16"

1 1/4"

..........

7025121

..........

⁽⁶⁾

⁽⁴⁾

1 17/32"

1 19/32"

2 1/4"

..........

7025122

..........

⁽⁶⁾

⁽⁴⁾

1 17/32"

1 19/32"

2 1/4"

..........

7025123

450-500

..........

⁽⁴⁾

1 1/2"

1 13/32"

1 1/2"

1 7/16"

25/32"

21/32"

7025124

..........

⁽⁶⁾

⁽⁴⁾

1 1/2"

1 13/32"

1 1/2"

1 7/16"

25/32"

21/32"

7025126

..........

⁽⁶⁾

⁽⁴⁾

1 17/32"

1 19/32"

2 1/4"

..........

7025127

450-500

..........

⁽⁴⁾

1 17/32"

1 19/32"

2 1/4"

..........

7025128

..........

⁽⁶⁾

⁽⁴⁾

1 17/32"

1 19/32"

2 1/4"

..........

7025150

550

500

1000 ⁽⁵⁾

1 15/32"

1 3/8"

1 1/16"

..........

7025151

600 ⁽⁷⁾

550 ⁽⁷⁾

1000 ⁽⁵⁾

1 15/32"

1 3/8"

1 1/16"

..........

7025157

..........

550 ⁽⁷⁾

1000 ⁽⁵⁾

1 7/16"

1 1/4"

..........

⁽¹⁾	Air Conditioning ON.

⁽²⁾	Transmission in NEUTRAL or PARK.

⁽³⁾	550 RPM with Air Conditioning.

⁽⁴⁾	No Adjustment. Fast idle will be correct when slow idle correctly set.

(5) - Flush with gasket surface of air horn.

⁽⁵⁾	Fast idle screw on low step of fast idle cam.

⁽⁶⁾	No idle speed specified. Set idle as low as possible in DRIVE for smooth idling and to prevent creep or harsh

⁽⁷⁾	Air Conditioning OFF.

⁽⁸⁾	Fast idle screw on high step of fast idle cam.

(10) - 500 RPM with modified carburetor.
(11) - 520 RPM with maximum air conditioner load.
(12) - 540-560 RPM with air conditioning OFF.
(13) - With vacuum assist. I 7/16" without vacuum assist.
(14) - Without float torsion spring on primary floats.
(15) - With float torsion spring on primary floats.
(16) - Air Conditioning OFF if equipped with idle compensator; ON if no idle compensator.
(17) - 1/2" without vacuum assist spring.
(18) - 575 RPM with Air Conditioning OFF.

⁽⁹⁾	Transmission in DRIVE except as noted.

(20) - 630-650 RPM with Air Conditioning OFF.
(21) - 520 RPM with two carburetors.

⁽¹⁰⁾	Fast idle screw on second highest step of fast idle cam against shoulder of top step.

⁽¹¹⁾	525 with Air Conditioning OFF.

(24) - 3/8" without vacuum assist, I 15/32" with vacuum assist.

⁽¹²⁾	600 RPM with Air Conditioning OFF.

⁽¹³⁾	283" Engine only. For 327" Engine: 475-500 RPM (Synchro-mesh), 450-475 RPM (Auto. Trans.).

(27) - Index for Turboglide.
(28) - 500-520 with Air Conditioning ON.
(29) - With fast idle screw on high step of fast idle cam, Air Conditioning ON. 2000 RPM with two carburetors.
(30) - 550 RPM (Air Cond. Cars) Air Cond. OFF.

ROCHESTER 4GC 4-BARREL CARBURETOR ADJUSTMENT SPECIFICATIONS (Table No. 2)

Rochester Carb. No.	Vacuum Assist Setting	Pump Rod Setting	Pump Rod Position	Idle Vent Setting	Choke Rod Setting	Initial Fast Idle Setting	Auto. Choke Setting	Unloader Setting
7020953	29/32"	1 1/64"	Outer	15/16"	.052"	.024"	1 Rich	.190"
7020955	1 1/16"	1 1/64"	Inner	29/32"	.052"	.024"	Index	.120"
7020985	1 1/8"	1 1/64"	Outer	15/16"	.052"	.024"	2 Rich	.190"
7022752	1 1/8"	1 1/64"	Outer	15/16"	.052"	.024"	2 Rich	.190"
7023006	..........	1 1/16"	Outer	31/32"	.055"	..........	Index	.230"
7023012	..........	1 1/16"	Outer	31/32"	.055"	..........	Index	.230"
7023030	1 1/16"	27/32"	..........	..........	.040"	..........	1 Rich	.130"
7023031	1 1/16"	27/32"	..........	..........	.040"	..........	1 Rich	.130"
7023040	..........	1"	Center	..........	.050"	.035"	Index	.130"
7023044	..........	29/32"	Center	..........	.045"	.030"	Index	.130"
7023045	..........	29/32"	Center	..........	.045"	.030"	Index	.130"
7023050	1 1/16"	1"	Inner	29/32"	.050"	.025"	Index	.120"
7023051	1 1/16"	1"	Inner	29/32"	.050"	.025"	Index	.120"
7023054	..........	1"	Outer	29/32"	.050"	.025"	Index	.190"
7023055	..........	1"	Outer	29/32"	.050"	.025"	Index	.190"
7023069	..........	15/16"	Inner	27/32"	.030"	.030"	Index	.150"
7023070	..........	15/16"	Inner	27/32"	.030"	.030"	Index	.150"
7023143	..........	1"	Center	..........	.050"	.035"	Index	.130"
7024030	1 1/16"	13/16"	Outer	..........	.040"	..........	Index	.125"
7024031	1 1/16"	13/16"	Outer	..........	.040"	..........	Index	.125"
7024040	..........	1 1/32"	Center	..........	.030"	..........	Index	.120"
7024044	..........	31/32"	Inner	..........	.050"	..........	2 Rich	.120"
7024045	..........	31/32"	Inner	..........	.050"	..........	Index	.120"
7024050	1 1/32"	1"	Inner	29/32"	.050"	..........	Index	.115"
7024051	1 1/32"	1"	Inner	29/32"	.050"	..........	Index	.115"
7024054	..........	1"	Inner	29/32"	.050"	..........	Index	.190"
7024055	..........	1"	Inner	29/32"	.050"	..........	Index	.190"
7024120	..........	1 1/16"	Outer	31/32"	.055"	..........	Index	.235"
7024121	..........	1 1/16"	Outer	31/32"	.055"	..........	Index	.235"
7024122	..........	1 1/16"	Outer	31/32"	.055"	..........	Index	.235"
7024123	1 7/32"	1"	..........	29/32"	.070"	..........	Index	.130"
7024124	1 7/32"	1"	..........	29/32"	.070"	..........	Index	.130"
7024125	..........	1 1/16"	Outer	31/32"	.055"	..........	Index	.235"
7024126	..........	1 1/16"	Outer	31/32"	.055"	..........	Index	.235"
7024127	1 5/32"	1 1/32"	..........	15/16"	.089"	..........	Index	.130"
7024128	1 5/32"	29/32"	..........	13/16"	.089"	..........	Index	.130"
7024153	1 1/32"	1"	Inner	29/32"	.050"	..........	Index	.115"
7024154	1 1/32"	1"	Inner	29/32"	.050"	..........	Index	.115"
7024220	..........	1 1/16"	Outer	31/32"	.055"	..........	Index	.235"
7024225	..........	1 1/16"	Outer	31/32"	.055"	..........	Index	.235"
7024226	..........	1 1/16"	Outer	31/32"	.055"	..........	Index	.235"
7025030	1 1/16"	13/16"	Outer	..........	.040"	.022"	Index	.125"
7025031	1 1/16"	13/16"	Outer	..........	.040"	.022"	Index	.125"
7025040	..........	1"	Center	..........	.060"	..........	Index	.120"
7025042	..........	1"	Center	..........	.060"	..........	1 Rich	.120"
7025050	1 3/32"	1"	Outer	29/32"	.050"	..........	1 Rich	.120"
7025051	1 1/8"	1"	Outer	29/32"	.050"	..........	1 Rich	.120"
7025054	..........	1"	Outer	29/32"	.050"	..........	Index	.120"
7025055	..........	1"	Outer	29/32"	.050"	..........	Index	.120"
7025121	..........	1 1/16"	Inner	31/32"	.055"	..........	Index	.250"
7025122	..........	1 1/16"	Inner	31/32"	.055"	..........	Index	.250"
7025123	1 5/32"	1 1/32"	..........	15/16"	.090"	..........	Index	.130"
7025124	1 5/32"	29/32"	..........	13/16"	.090"	..........	Index	.130"
7025126	..........	1 1/16"	Inner	31/32"	.055"	..........	Index	.250"
7025127	..........	1 1/16"	Outer	31/32"	.055"	..........	Index	.250"
7025128	..........	1 1/16"	Inner	31/32"	.055"	..........	Index	.250"
7025150	13/16"	1"	Outer	29/32"	.050"	..........	1 Rich	.120"
7025151	25/32"	1"	Outer	29/32"	.050"	..........	1 Rich	.120"
7025157	..........	1"	Outer	29/32"	.050"	..........	Index	.120"

ROCHESTER 4GC 4-BARREL CARBURETOR ADJUSTMENT SPECIFICATIONS (Table No. 1)

Rochester Carb. No.

Hot Idle Speed (Engine RPM)

Fast Idle Eng. RPM

Float Level Setting

Float Drop Setting

Float Toe Setting

S.M. Trans.

Auto. Trans. ⁽⁵⁾

Pri.

Sec.

Pri.

Sec.

Pri.

Sec.

7025158

600 ⁽³⁾

..........

1000 ⁽²⁾

1 7/16"

1 1/4"

..........

7025185

475

450

..........

1 17/32"

1 19/32"

2 1/4"

..........

7025186

475

450

..........

1 17/32"

1 19/32"

2 1/4"

..........

7025255

600 ⁽³⁾

550 ⁽³⁾

1000 ⁽²⁾

1 15/32"

1 3/8"

1 1/16"

..........

7026030

..........

480-500 ⁽¹⁾

1700-1750 ⁽⁴⁾

1 7/16"

1 3/8"

1 1/2"

1 1/16"

5/8"

3/8"

7026031

..........

480-500 ⁽¹⁾

1700-1750 ⁽⁴⁾

1 7/16"

1 3/8"

1 1/2"

1 1/16"

5/8"

3/8"

7026040

..........

500 ⁽⁶⁾

650 ⁽²⁾

1 13/32"

1 1/16"

..........

7026121

450-500 ⁽¹⁾

..........

1 17/32"

I 19/32"

2 1/4"

..........

7027085

..........

7036118

..........

600 ⁽³⁾

..........

1 17/32"

1 19/32"

2 1/4"

..........

7036119

700 ⁽³⁾

..........

1 17/32"

1 19/32"

2 1/4"

..........

7036120

..........

600 ⁽³⁾

..........

1 17/32"

1 19/32"

2 1/4"

..........

7036121

700 ⁽³⁾

..........

1 17/32"

1 19/32"

2 1/4"

..........

7037081

..........

⁽¹⁾	Air Conditioning ON.

(2) - Transmission in NEUTRAL or PARK.
(3) - 550 RPM with Air Conditioning.
(4) - No Adjustment. Fast idle will be correct when slow idle correctly set.
(5) - Flush with gasket surface of air horn.

⁽²⁾	Fast idle screw on low step of fast idle cam.

(7) - No idle speed specified. Set idle as low as possible in DRIVE for smooth idling and to prevent creep or harsh

⁽³⁾	Air Conditioning OFF.

⁽⁴⁾	Fast idle screw on high step of fast idle cam.

⁽⁵⁾	Transmission in DRIVE except as noted.

(20) - 630-650 RPM with Air Conditioning OFF.
(21) - 520 RPM with two carburetors.
(22) - Fast idle screw on second highest step of fast idle cam against shoulder of top step.
(23) - 525 with Air Conditioning OFF.
(24) - 3/8" without vacuum assist, I 15/32" with vacuum assist.
(25) - 600 RPM with Air Conditioning OFF.
(26) - 283" Engine only. For 327" Engine: 475-500 RPM (Synchro-mesh), 450-475 RPM (Auto. Trans.).
(27) - Index for Turboglide.
(28) - 500-520 with Air Conditioning ON.
(29) - With fast idle screw on high step of fast idle cam, Air Conditioning ON. 2000 RPM with two carburetors.

⁽⁶⁾	550 RPM (Air Cond. Cars) Air Cond. OFF.