Carburetor - Holley 2280 & 6280 2-bbl Dodge Ram Van II

COMPONENT TESTING

Note. Specific component testing information not available. Refer to any tests performed during ADJUSTMENTS or OVERHAUL procedures.

APPLICATION

CHRYSLER CORP. (HOLLEY) CARBURETOR NO.

IDENTIFICATION

Carburetor part number is stamped on main body flange. It is in front of lever, controlled by throttle position transducer, under choke vacuum diaphragm.

DESCRIPTION

Holley model 2280 and 6280 2-barrel carburetors use 4 basic fuel metering systems: basic idle, accelerator pump, main metering, and power enrichment. Fuel inlet and choke systems are also used. In addition, some models are equipped with a solenoid idle stop (SIS) and bowl vent solenoid.

The basic idle system provides mixture during idle and low speed engine operation. The accelerator pump system provides additional fuel for acceleration. The main metering system operates during normal cruising, and the power enrichment system provides a richer mixture when high power output is required (full throttle operation).

ADJUSTMENTS

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

FLOAT LEVEL

1. With air horn and gasket removed, turn main body upside-down. Catch pump intake check ball as it falls out. Hold float hinge pin retainer in place with finger to fully seat float pin in cradle.
2. Using a "T" scale, measure float level from air horn gasket surface on main body to toe of each float. (Scheme 13) To adjust, bend float tang. If necessary, bend either float arm to equalize float positions.

Adjusting Float Level Measure from air horn gasket surface to toe of each float. Scheme 13

CHOKE VACUUM KICK

1. Open throttle and close choke. Close throttle to trap fast idle cam in closed choke position. (Scheme 14) Disconnect vacuum hose from choke diaphragm. Connect hand-held vacuum pump to diaphragm, and apply at least 15 in. Hg vacuum.
2. Apply light finger pressure on choke shaft lever to compress spring in diaphragm stem without distorting linkage. Diaphragm stem reaches a stop as spring is compressed.
3. Measure choke vacuum kick clearance between upper edge of choke valve and air horn wall. (Scheme 14) To adjust, open or close "U" bend in vacuum diaphragm link. Check all linkage for freedom of movement. Remove vacuum pump, and install vacuum hose on diaphragm.

Adjusting Choke Vacuum Kick Spring in diaphragm stem must be compressed during adjustment. Scheme 14

FAST IDLE CAM POSITION

1. Position fast idle speed screw on second step of fast idle cam. Apply light finger pressure on choke shaft lever to close choke valve. (Scheme 15)
2. Measure fast idle cam clearance between center of upper edge of choke valve and air horn wall. Clearance can be measured using a drill or pin gauge. To adjust, bend fast idle cam link rod at "U" bend.

Adjusting Fast Idle Cam Position Place idle speed screw on second step of fast idle cam. Scheme 15

CHOKE UNLOADER

1. Hold throttle valves in wide open position. Apply light finger pressure on choke shaft lever to close choke valve. (Scheme 16)
2. Check choke unloader clearance between upper edge of choke valve and air horn wall. Clearance can be checked using a drill or pin gauge. To adjust, bend choke unloader tang on accelerator pump lever.

Adjusting Choke Unloader Adjust choke unloader with throttle valves wide open. Scheme 16

Model 2280 Only

1. Remove bowl vent cover. Hold throttle lever in wide open position. (Scheme 17) Insert a 5/64" Allen wrench in mechanical power valve adjustment screw.
2. Push down on screw, then release to determine if there is any clearance. If so, turn screw clockwise until there is no clearance. To adjust, turn screw counterclockwise one full turn from zero clearance. Install bowl vent cover and gasket.

Adjusting Mechanical Power Valve Adjust power valve clearance with 5/64" Allen wrench. Scheme 17

ACCELERATOR PUMP STROKE

1. Remove bowl vent cover and gasket. With pump links and levers installed, adjust throttle blades to closed position by backing out idle speed screw.
2. Set distance from top of pump lever to top of bowl vent cover surface to .210" (5.3 mm) by bending pump link. Check that wide open throttle can be reached without binding. Install gasket and bowl vent cover plate.

Note. If accelerator pump adjustment is changed, mechanical power valve and bowl vent valve on model 2280 carburetor must be re-adjusted.

Adjusting Accelerator Pump Stroke Clearance between cap nut and pump lever should be zero. Scheme 18

1. Remove bowl vent valve cover and vent valve lever spring. Be careful not to dislodge or lose vent valve lever retainer. With throttle at curb idle position, press firmly down on vent valve lever where spring seats.
2. Check clearance between vent valve tang and lever with drill or pin gauge. (Scheme 19) Clearance should be.035" (.89 mm). To adjust, bend end of vent valve tang up or down until gauge just fits through contact area.

Adjusting Bowl Vent Valve Check adjustment with throttle at curb idle position. Scheme 19

DISASSEMBLY

1. Place carburetor on repair stand to prevent damage to throttle valves. Remove air cleaner bolt and retainer. Remove cotter pin from accelerator pump arm link and remove link.
2. Remove bowl vent solenoid assembly from air horn (if used). Remove choke vacuum diaphragm, linkage, and bracket. Remove nut and washer securing fast idle cam lever to choke shaft.
3. Disconnect fast idle cam rod from lever and fast idle cam. Disconnect and remove accelerator operating link. Remove 6 air horn screws. Lift air horn straight up from main body.
4. Remove and discard air horn gasket. Remove accelerator pump operating shaft retaining clip and pull shaft straight out. Remove accelerator pump arm and internal pump lever.
5. On model 6280, remove accelerator pump plunger cap nut with one wrench while holding pump plunger steady with other wrench. Remove accelerator pump plunger.
6. On all models, remove vacuum power valve piston by gently prying up vacuum piston retaining ring tangs. Remove mechanical power valve push rod and spring assembly by gently prying off plastic cap and removing clip.
7. Remove fuel inlet fitting and gasket. Discard gasket. Remove float hinge pin retainer, hinge pin, float baffle and float assembly. Using a screwdriver, remove main metering jets.
8. Using Power Valve Remover (C-4231), remove vacuum power valve and mechanical power valve. Make sure blade of tool is squarely seated in slots of valves to avoid damage. NOTE: DO NOT interchange mechanical and vacuum power valve assemblies. Vacuum power valve needle is about .050" longer than mechanical power valve needle. The vacuum power valve needle has an undercut groove just above needle stop. Mechanical power valve is located on choke side of carburetor. DO NOT mix up valve seats. Assemblies must be installed in original locations, and must be kept with their respective needle and spring assembly.
9. Remove venturi cluster screws. Lift cluster and gasket up and away from main body. DO NOT remove idle well tubes. Turn main body upside-down and catch accelerator pump weight and check ball.
10. Remove 4 throttle body screws. Separate throttle body from main body and discard gasket. Remove fast idle cam retaining clip, and slide cam off stub shaft.
11. Remove idle mixture screw plugs. Center punch each idle mixture screw housing about 1/4" from end of housing. Drill through outer section of housing at punch mark with 3/16" drill. Pry plug out of housing and save for reassembly. Remove idle mixture screws and springs.

CLEANING & INSPECTION

1. Use a regular carburetor cleaning solution. Soak components long enough to thoroughly clean all surfaces and passages of foreign matter.
2. DO NOT soak any rubber or plastic parts in cleaner, particularly choke diaphragm and heater. These parts are best cleaned with a clean cloth and/or soft brush.
3. DO NOT use drills or wire to clean jets or other passages.
4. If cleaner manufacturer recommends rinsing with water, hot water will give best results.
5. Blow out all passages with dry, compressed air.

Exploded View of Holley Model 2280 2-Barrel Carburetor. Scheme 20

REASSEMBLY

1. Install idle mixture screws and springs. Gently seat both mixture screws by hand. Now back out one full turn as a preliminary idle mixture adjustment.
2. Install fast idle cam on stub shaft with steps facing fast idle speed screw. Install retaining clip. Turn main body upside-down. Place throttle body gasket in position.
3. Position throttle body on main body. Install 4 attaching screws, and tighten to 30 INCH lbs. (3 N.m). Install accelerator pump discharge check ball and weight.
4. Fill fuel bowl with clean fuel, and check ball and seat operation. Hold ball and weight down with a small brass rod. Place accelerator pump plunger in well, and operate by hand. If no resistance is felt, check ball is leaking.
5. Remove weight and leave check ball in place. Using a small drift punch, lightly tap ball against seat to form a new seal. Remove old check ball and discard. Install a new ball and weight. Perform fuel leak test again.
6. If there is still no resistance felt, main body must be replaced. If resistance is felt, check ball is seating correctly. Install new venturi cluster gaskets. Install venturi cluster in position in main body. Install screws and tighten securely.
7. Install main metering jets. Install mechanical and vacuum power valves. Use care not to damage power valve needles. Ensure valves are installed in original locations as noted during disassembly.
8. Install hinge pin in float. Insert hinge pin through slot in float baffle. Tabs on baffle should point down. Place assembly in pin cradle in main body. Install hinge pin retainer. Install fuel inlet fitting with new gasket. Perform float level adjustment.
9. Install vacuum power piston spring and piston. Install retaining ring over piston and carefully seat in place. Check piston operation for binding or sticking. If piston binds or sticks enough to prevent smooth operation, install new piston.
10. Install mechanical power valve push rod spring, rod and retaining clip. Install plastic cap on push rod. Install accelerator pump assembly through air horn and install cap nut.
11. Install new air horn gasket. Carefully lower air horn into position on main body, guiding accelerator pump plunger into its cylinder. Use care not to damage accelerator pump plunger. Install air horn screws. Starting from center and working out, tighten screws to 25 INCH lbs. (2.8 N.m).
12. With pump override spring retainer contacting air horn boss, adjust cap nut for a clearance of .310" (8 mm) between housing surface and cap nut. Install accelerator pump lever, operating shaft, and retaining clip.
13. Connect plain end of fast idle cam link rod to slot in fast idle cam from inside of cam. Engage other end of rod in choke lever. Place choke valve in wide open position. Align flats, and slide choke lever onto choke shaft.
14. Install lock washer and tighten nut. Install accelerator pump operating link. Connect choke vacuum break diaphragm rod to slot in choke lever. Install diaphragm assembly and tighten screws. Install idle speed solenoid.
15. Install bowl vent solenoid assembly. Install bowl vent cover plate with new gasket. Install accelerator pump lever, using a new cotter pin. Install air cleaner bolt and retainer.

SPECIFICATIONS

CARBURETOR ADJUSTMENT SPECIFICATIONS

See also:
• ADJUSTMENTS
• OVERHAUL