Carburetor Overhaul - Rochester e2se/2se 2-bbl Chevrolet Camaro II

INTRODUCTION

GENERAL MOTORS (ROCHESTER) CARBURETOR NO. (2.8L)

IDENTIFICATION

The Rochester 2SE and E2SE carburetor numbers are stamped vertically on the float bowl next to vacuum tube "B" location. If float bowl is replaced, follow manufacturer's instructions contained in service package to transfer part number to new float bowl.

Carburetor Identification Label Original part number must be transferred from old float bowl if new float bowl is installed. Scheme 1

DESCRIPTION

The Rochester Varajet Carburetor models 2SE and E2SE are 2-stage, 2-barrel downdraft carburetors. The primary stage consists of a triple venturi with a 35 mm bore. The secondary stage has a 46 mm bore and is equipped with an air valve with a single tapered metering rod. Both are equipped with integral, electronically-activated chokes, a choke vacuum break diaphragm and an idle speed solenoid.

All E2SE models are equipped with an electrically operated mixture control solenoid. The mixture control solenoid is mounted on the air horn and extends into fuel bowl. Fuel metering is controlled by the mixture control solenoid plunger opening and closing the fuel passage to the main metering jet.

All General Motors models are equipped with a Throttle Position Sensor (TPS) to electrically signal the ECM of throttle position.

All General Motors carburetors are equipped with a temperature regulated pump system with a thermostatically controlled by-pass valve. The by-pass valve is permanently pressed into the air horn. All carburetors are equipped with tamper-resistant features

Factory-adjusted rich mixture screws, factory-adjusted lean mixture screws, riveted choke coil housing and hardened steel pump lever (E2SE models only). All models are also equipped with idle mixture screw plugs.

ADJUSTMENT

Note. For all on-vehicle adjustments not covered in this article, see appropriate TUNE-UP article.

ANGLE GAUGE ADJUSTMENT TOOL

Manufacturer recommends that some carburetor adjustments be performed using a Choke Valve Angle Gauge (Kent-Moore Tool No. J-26701). While preparations and actual adjustments may vary with each individual adjustment, the procedure for using the angle gauge to check the choke valve angle remains the same. Use the following procedure to perform adjustments requiring the use of the choke angle gauge. (Scheme 2)

Choke Valve Angle Gauge This gauge must be used to perform some adjustments. Scheme 2

1. Rotate degree scale on angle gauge so that 0° mark is opposite pointer.
2. With choke valve closed, place angle gauge magnet squarely on choke valve.
3. Rotate leveling bubble on angle gauge until it is centered.
4. Rotate degree scale until specified degree mark is opposite pointer.
5. Now perform individual adjustment preparation as outlined in the following carburetor adjustments requiring an angle gauge.
6. If bubble is centered, adjustment is correct. If not, adjust carburetor as outlined in adjustment procedure.

FLOAT LEVEL (WET SETTING)

Note. This is an on-vehicle adjustment.

Scheme 3

1. Remove air horn vent stack and screen. If using Float Gauge (J-9789-135), remove air horn screw next to open vent. If using Float Gauge BT-8104, removal of screw is not necessary. (Scheme 3)
2. With engine running at idle, choke wide-open, insert gauge in bridge or guide hole. Gauge J-9789-135 has a tang which fits into screw hole to hold gauge upright. Gauge BT-8104 requires use of the bridge to hold gauge upright. Allow float gauge to float freely. (Scheme 3) NOTE: Pressing down on float gauge could result in float damage or carburetor flooding. (Scheme 3): Wet Float Level Adjustment Allow float gauge to float freely.
3. With gauge floating freely, observe mark on gauge which aligns with top of casting or bridge (at eye level). Reading should be within 1/16" of specified float level. Incorrect fuel pressure will affect fuel level.
4. If reading is not within 1/16" of specified float level, remove carburetor. Remove air horn and perform Float Level (Dry Setting) adjustment.

Scheme 4

1. Remove air horn and gasket from float bowl. Hold float retainer firmly down while lightly pushing float down against needle. (Scheme 4) (Scheme 4): Dry Float Level Adjustment Bend float arm to adjust.
2. Position a "T" scale over large toe of float at point furthest away from float hinge pin. Measure distance from float bowl casting to float. NOTE: A new set of External Float Gauges (J-9789-135) are available for 2SE and E2SE carburetors. By selecting proper gauge for specific carburetor being checked, a simple "On car" check can be made without removing air horn from float bowl. Just remove vent stack and air horn screw and insert gauge in air horn screw hole. Let it float freely.
3. To adjust, remove float and bend float arm. Use care in removing float as some models may be equipped with a float stabilizer spring. Check to make sure float is correctly aligned after adjustment.

Air Valve Spring Adjustment (General Motors Only) Remove intermediate choke rod to gain access to lock screw, if required. Scheme 5

1. Remove intermediate choke rod to gain access to lock screw, if required. Using an Allen wrench, loosen air valve lock screw. Using a screwdriver, turn tension adjusting screw clockwise until air valve opens slightly. (Scheme 5)
2. Turn tension adjusting screw counterclockwise until air valve just closes. Turn adjusting screw additional specified turns (counterclockwise).
3. Tighten air valve lock screw. Coat air valve shaft pin and closing spring contact areas with lithium base grease.

CHOKE COIL LEVER

Note. DO NOT remove rivets and retainers holding choke cover and coil assembly in place unless necessary to check choke coil lever adjustment. If rivets and cover are removed, a new rivet service kit must be installed.

Choke Coil Lever Adjustment Bend rod to adjust. Scheme 6

1. Remove rivets and choke thermostatic cover from choke housing. Place fast idle screw on high step of fast idle cam. (Scheme 6)
2. Push on intermediate choke lever until choke valve is fully closed.
3. Insert a specified drill or pin gauge in hole provided in choke housing. Edge of choke lever inside housing should just touch drill or pin gauge.
4. To adjust, support intermediate choke rod at "S" in (Scheme 7) and bend intermediate choke rod. Reinstall choke cover and adjust.

CHOKE ROD (FAST IDLE CAM)

Note. Choke coil lever adjustment must be correct before proceeding. This adjustment makes use of choke angle gauge. See procedure at beginning of Adjustments.

Choke Rod (Fast Idle Cam) Adjustment Bend rod to adjust. Scheme 7

1. Attach rubber band to intermediate choke lever. Open throttle to allow choke valve to close. Set up angle gauge.
2. Place fast idle speed screw on second step of fast idle cam against shoulder of highest step. (Scheme 7) Close choke valve by pushing on choke shaft lever to open choke valve and to make contact with closing tang.
3. Bubble on choke angle gauge should be centered with specified degree mark opposite pointer.
4. To adjust, support fast idle cam rod at "S" in (Scheme 8) and bend fast idle cam rod until bubble of choke valve angle gauge is centered.

PRIMARY VACUUM BREAK

Note. This adjustment is performed using the choke valve angle gauge. See procedure at beginning of Adjustments.

Primary Vacuum Break Adjustment Turn screw or bend rod with vacuum still applied. Scheme 8

1. Attach rubber band to intermediate choke lever. Open throttle to allow choke valve to close.
2. Set up angle gauge and set angle to specification. Using an outside vacuum source of at least 18 in. Hg, retract vacuum break plunger. Plug air bleed hole with tape or pump plunger cup, if equipped. (Scheme 8) Air valve rod should not prevent seating of vacuum break diaphragm. NOTE: Be sure plunger bucking spring is compressed and seated (plunger fully extended), if equipped.
3. To adjust on models with hex-head adjustment, use a 1/8" hex wrench to turn screw in rear cover until bubble is centered. Apply RTV silicone sealant over screw head to seal setting. To adjust on models without hex-head adjustment, support vacuum break rod and bend rod with vacuum still applied. (Scheme 9)

AIR VALVE ROD

Note. This adjustment is made by using the choke valve angle gauge. See procedure at beginning of Adjustments.

Air Valve Rod Adjustment Bend rod to adjust. Scheme 9

1. Set up angle gauge on air valve. Using an outside vacuum source of at least 18 in. Hg, seat primary choke vacuum break diaphragm plunger. (Scheme 10) NOTE: Plug end cover on models with primary vacuum break only, using tape or accelerator pump plunger cup. Cup must be removed after adjustment is completed.
2. Apply light opening pressure to air valve lever. To adjust, support air valve rod and set to specified angle by bending air valve rod at a point near its connection to primary vacuum break (models equipped with primary vacuum break only) or at a point near its connection to air valve lever (models equipped with primary and secondary vacuum breaks).

AUTOMATIC CHOKE

Choke coil cover is retained on housing with rivets to prevent tampering with factory adjustment. If necessary to remove cover, refer to Disassembly and Reassembly procedures in this section.

SECONDARY VACUUM BREAK

Note. This adjustment is performed using the choke valve angle gauge. See procedure at beginning of Adjustments.

Secondary Vacuum Break Adjustment Turn screw or bend rod with vacuum still applied. Scheme 10

1. Attach rubber band to intermediate choke lever. Open throttle to allow choke valve to close.
2. Set up angle gauge and set angle to specification. Using an outside vacuum source of at least 18 in. Hg, retract vacuum break plunger. (Scheme 11)
3. Where applicable, plug air bleed holes and ensure plunger stem is fully extended to compress plunger bucking spring.
4. To adjust on models with hex-head adjustment, use a 1/8" hex wrench to turn screw in rear cover until bubble is centered. Apply RTV silicone sealant over screw head to seal setting. To adjust on models without hex-head adjustment, support vacuum break rod and bend rod with vacuum still applied. (Scheme 10)

CHOKE UNLOADER

Note. This adjustment is performed using the choke valve angle gauge. See procedure at beginning of Adjustments.

Choke Unloader Adjustment Bend choke unloader tang to adjust. Scheme 11

1. Attach rubber band to intermediate choke lever. Open throttle to allow choke valve to close. (Scheme 11)
2. Set up angle gauge and set angle to specifications. Hold throttle lever in wide open position.
3. Push on choke shaft lever to open choke valve and to make contact with closing tang. To adjust, bend tang on throttle lever until bubble is centered.
4. Remove gauge and reinstall choke cover and coil assembly if previously removed. Install service rivet and retainer kit.

Scheme 12

1. Hold choke valve wide open by pushing down on intermediate choke lever. (Scheme 12)
2. Open throttle lever until end of secondary actuating lever is opposite toe of lockout lever. (Scheme 12): Secondary Throttle Lockout Adjustment Bend lockout lever to adjust.
3. Measure specified clearance between end of actuating lever and toe of lockout lever. Measurement can be checked using a drill or pin gauge of specified size.
4. To adjust, bend lockout lever tang contacting fast idle cam.

DISASSEMBLY

Note. Before disassembling carburetor, mount unit in a suitable holding fixture to prevent damage to throttle valves or linkage.

Air Horn

1. Remove idle speed solenoid/primary vacuum break bracket retaining screws. Remove bracket assembly. Disengage vacuum break link from slot in choke lever. Lift and rotate bracket assembly to remove air valve rod from slot in air valve lever.
2. If equipped, remove secondary vacuum break bracket attaching screws. Rotate bracket assembly to disengage vacuum break link from choke lever slot.
3. On 2SE models (NOT USING a clip to secure the accelerator pump rod), remove pump lever retaining screw from air horn. Rotate pump lever to remove from pump rod. On E2SE models (using a clip to secure pump rod), remove clip and remove pump rod from hole in pump lever. CAUTION: DO NOT remove pump lever retaining screw from models using clip as pump rod retainer. Pump lever and washer must be removed from air horn assembly on these models.
4. Remove and discard retaining clip from intermediate choke rod at choke lever. Use a new retaining clip during reassembly. Remove choke rod and plastic bushing from choke lever. Bushing may be reused.
5. If equipped, remove hot idle compensator valve screws. Remove valve and seal from air horn. Discard seal. Valve removal is necessary to gain access to short air horn-to-bowl attaching screw.
6. On E2SE models, remove 3 mixture control solenoid screws and remove mixture control solenoid using a light twisting motion. Remove and discard solenoid gasket, plunger seal and plunger seal retainer.
7. Remove all air horn-to-float bowl screws and lock washers. Remove vent stack and screen assembly. Rotate fast idle cam up as f`r as possible. Rotate air horn and tilt to disengage fast idle cam rod from slot in fast idle cam and pump rod from pump lever hole. NOTE: If pump plunger comes out of float bowl with air horn removal, remove pump plunger from air horn. Air horn gasket should remain on float bowl. DO NOT remove fast idle cam screw and cam from float bowl. These parts must remain permanently in place as installed by manufacturer. Service replacement float bowl will include fast idle cam screw and cam.
8. Disconnect fast idle cam rod from choke lever by aligning tang on rod with slot in lever. Lift off air horn assembly.
9. If equipped, remove TPS plunger by pushing downward through seal in air horn. Remove seal retainer and seal. Remove accelerator pump plunger seal from air horn after using a small screwdriver to remove staking around each seal retainer. NOTE: Use fingers only (no tools) when removing plunger to prevent damage to sealing surface. Use care in removing plunger seal retainer and plunger stem seal retainer to prevent damage to air horn. Discard seals and retainers.
10. No further disassembly of air horn is required. Air valve and choke valve attaching screws are staked in place and not removable. New service replacement air horn assembly includes secondary metering rod and air valve assemblies with preset factory adjustments. No attempt should be made to change air valve settings.

Float Bowl

1. Remove air horn gasket. Remove pump plunger and pump spring from pump well. Remove plastic filler block from float valve.
2. Remove float assembly and float valve, pulling up on retaining pin. If equipped, remove float stabilizing spring with float assembly. Remove float needle seat, gasket and extended metering jet from float bowl. Use jet tool or screwdriver that fully fits slot in top of jet. NOTE: DO NOT remove or adjust small calibration screw located deep inside metering jet. Adjustment should be made only if required by a Computer Command Control System performance check.
3. On E2SE models, push up from bottom on electrical connector and remove TPS and connector from float bowl. Remove spring from bottom of TPS well in bowl. On 2SE models, press down on power piston stem and allow it to snap up. Repeat this until plastic retainer is dislodged and remove power piston and metering rod assembly.
4. Remove spring from power piston bore. If necessary to remove metering rod from hanger, compress spring on metering rod and align groove on rod with slot in holder. Care must be taken not to damage tip of metering rod.
5. Remove main metering jet using a screwdriver that fits tight in groove. Using a small slide hammer, remove plastic retainer holding pump discharge spring and check ball in place in float bowl. Discard retainer.
6. To remove choke cover and coil assembly, align a .159" (No. 21) drill on choke cover retaining rivet. Drill only enough to remove rivet heads. Remove rivets, choke cover and coil assembly. Remove screw from end of intermediate choke shaft in choke housing. Remove choke coil lever from shaft.
7. Slide intermediate choke shaft out of float bowl. Remove choke housing screws and remove choke housing. Remove fuel inlet nut, gasket, check valve/filter and spring.
8. Remove 4 screws securing throttle body to float bowl. Remove throttle body. Remove throttle body insulator gasket.

Throttle Body

1. Hold throttle valves wide open. Disengage pump rod from throttle lever by rotating rod until tang on rod aligns with slot in lever.
2. Remove curb idle and fast idle speed screws and springs if necessary. Further disassembly of throttle body is not required. Throttle valve screws are permanently staked in position. NOTE: DO NOT remove idle mixture screw plug unless it is necessary to replace mixture screw or cleaning and air pressure fail to clean idle mixture passages. If necessary to remove, proceed as follows
3. Invert throttle body and position on a holding fixture with manifold side up. Using a small hacksaw, make 2 small cuts, one on either side of mixture screw plug location. Position a small flat punch on throttle body between cuts.
4. Drive punch down and break out portion of throttle body between the 2 cuts. Hold punch at a 45° angle and drive out hardened steel plug. NOTE: Plug will shatter when struck. Remove loose pieces to allow the use of mixture adjusting tool or thin walled deep 3/16" socket to remove adjusting screw and spring.
5. Turn mixture screw in carefully, counting turns needed to seat screw. Record number to be used in reassembly, then remove mixture screw.

CLEANING & INSPECTION

1. DO NOT soak any components containing rubber, leather or plastic. Definitely DO NOT soak idle speed solenoid, mixture control solenoid, throttle position sensor, electric choke, diaphragms, pump plunger and plastic filler block. Plastic bushings will withstand normal cleaning.
2. Use a regular carburetor cleaning solution. Soak components long enough to thoroughly clean all surfaces and passages of foreign matter.
3. Remove any residue after cleaning by rinsing components in a suitable solvent.
4. Blow out all passages with dry compressed air.
5. Test mixture control solenoid for sticking, binding or leaking. Connect jumper wire between battery positive terminal and right (positive) solenoid terminal. Connect another jumper wire between battery negative terminal and left (negative) solenoid terminal. Remove rubber seal and retainer from solenoid stem and attach and vacuum pump and gauge. (Scheme 14) Apply 25 in. Hg of vacuum.
6. Time leak-down rate from 20 in. Hg to 15 in. Hg. If time exceeds 5 seconds, replace solenoid. Remove jumper wires. Apply 15 in. Hg of vacuum. Vacuum should drop to zero in less than 1 second. If not, replace solenoid.

Testing Mixture Control Solenoid (Disassembled From Carburetor) Connect to battery voltage for testing. Scheme 13

Exploded View of Rochester 2SE 2-Barrel Carburetor. Scheme 14

Exploded View of Rochester E2SE 2-Barrel Carburetor. Scheme 15

REASSEMBLY

Note. Use new gasket and seals. Make sure new gaskets fit correctly and all holes are punched through and properly located.

To reassemble carburetor, reverse disassembly procedure and note the following

Scheme 16

1. Install fuel inlet needle pull clip over edge of flat on float arm facing float. DO NOT hook clip in holes in float arm.
2. After throttle body is installed on float bowl, make sure secondary lockout tang is in correct position to engage secondary lockout lever.
3. Install new accelerator pump discharge check ball and spring plastic retainer. Insert end of retainer in spring and place in position in float bowl. Lightly tap retainer into position until it is flush in float bowl.
4. Make sure holes in fuel filter face toward fuel inlet fitting when filter is installed.
5. Some linkage retaining clips are dished. Make sure portion of clip that bends outward is toward end of rod. Make sure clip makes full contact with rod.
6. Place fast idle screw on high step of fast idle cam. Install choke coil cover, aligning notch in cover with raised boss on housing cover flange. NOTE: If choke cover and coil assembly was removed from housing, a service rivet kit must be installed to restore tamper-resistant feature. CAUTION: On E2SE models, be sure coil pick-up lever is located inside choke coil tang. Also, on electric chokes, the ground contact is provided by a metal plate at rear of choke cover assembly. DO NOT install a choke cover gasket between electric choke assembly and choke housing.
7. Mixture control solenoid connector must be installed with Pink wire on right hand terminal of connector, as viewed from harness end. On some models, the connector latch may require minor filing to allow proper latching.
8. Install air horn screws, noting location and type of screw for correct installation. Tighten screws evenly, securely and in proper sequence. (Scheme 16) (Scheme 16): Air Horn Screw Location & Tightening Sequence
9. On E2SE models, install mixture control solenoid seal on solenoid stem. Using a 3/16" socket and hammer, lightly tap retainer in place, on stem, leaving a slight clearance between retainer and seal. Apply silicone grease to seal before installation of solenoid.

SPECIFICATIONS

CARBURETOR ADJUSTMENT SPECIFICATIONS (E2SE)