Tillotson Tc3A Carburator

Transcription

1 Tillotson Tc3A Carburator 176 FUEL SYSTEMS - 5B-11

2 CENTER BOWL TYPE CARBURETOR Removal 1. Remove front cowl cover and wrap-around cowl. 2. Remove swivel link from lower carburetor. (Figure 2) 3. Loosen carburetor synchronizing linkage set screw with 1/8" alien wrench. 4. Remove fuel line clamp(s) and remove fuel line from fitting(s). 5. Remove carburetor flange retainer nuts (9/16"), then remove carburetor from crankcase studs. 6. Clean all old gasket material from crankcase flange, being careful not to damage gasket surface. a - Swivel Link b - Set Screw (Not Visible) c - Flange Nuts (3 on Opposite Side Not Visable) d - Air Horn e - Float Bowl Retainer Screws and Nuts Figure 2. Carburetor Removal Disassembly 1. Remove air horn (two 3/16" allen head screws). 2. Remove idle mixture adjustment screw and spring. 3. Remove 4 float bowl retainer bolts and nuts. 4. Remove float hinge pin, float and inlet needle. (Figure 3) 5. Remove main fuel jet. 6. Remove 2 float bowl gaskets.remove fuel baffle. a - Hinge Pin b Float c - Inlet Needle (Under Tab) d - Main Fuel Jet Figure 3. Float Hinge Pin Removal

3 Cleaning and Inspection 1. Place carburetor body, bowl, throttle shaft, throttle plate, main fuel jet and float hinge pin in carburetor cleaning solution for a period of time to remove all dirt, gum and varnish which may have accumulated. CAUTION: DO NOT place float and/or inlet needle in carburetor cleaner, as it may damage non-metalic materials. NOTE: Carburetor cleaners are available through local automotive supply stores. 2. After soaking carburetor parts, rinse thoroughly with water, then solvent. Blow parts dry with compressed air. Be sure to blow through all passages, orifices and nozzles. 3. Check for float deterioration (saturation). 4. Check inlet needle tip for looseness, cuts and/or grooves (replace inlet needle if any of the preceding are found). a Baffle b - Gasket Recess Figure 4. Fuel Baffle Installation

4 Reassembly 1. Using the proper size screwdriver, install main fuel jet. 2. Place fuel baffle into float bowl gasket recess of carburetor body as shown in Figure Place gasket into carburetor body recess. 4. Insert inlet needle into seat. Check that inlet needle does not stick inside seat. 5. Install float and float pin. 6. Check and/or adjust float height for 13/32" (10.3mm). (Figure 5) With carburetor inverted from operating position, bend float level tab (Figure 5) to attain a measurement of 13/32" between float bowl mounting surface (with inlet needle seated) and float surface opposite the hinge pin. a - 13/32" (10.3mm) b- Tab Figure 5. Float Height Adjustment 7. Place carburetor in normal operation position (with float allowed to hang down). Bend float level drop tang (Figure 6) to attain a measurement of 27/32" (21.4mm) between float bowl mounting surface and lower edge of float. Measurement is made opposite float hinge pin. 8. Secure gasket to center of float bowl and install float bowl to carburetor body, with main fuel jet plug aligned with main fuel jet. Be certain that gasket in float bowl is not displaced during assembly. 9. Secure float bowl with 4 bolts and nuts. Tighten bolts evenly to avoid possibility of leakage. 10. Place spring over idle mixture screw and install screw into carburetor until it seats lightly, then back screw out one full turn. 11. Place a drop of Loctite Type 35 onto air horn screw threads and install air horn. a - 27/32" (21.4mm) b - Ta b ( N o t Vi s i b l e ) Figure 6. Float Drop Adjustment

5 Installation 1. Place a new flange gasket onto carburetor mounting studs. Install carburetor and secure with 2 nuts. 2. Move throttle plates on all carburetors to closed throttle position and secure allen head set screw in swivel block to link rod. 3. Install fuel line(s) to inlet fitting(s) and secure with clamp(s). 4. Install drag link swivel to bottom carburetor, if removed. Adjustments CARBURETOR ADJUSTMENTS 1. Main fuel jet size recommendations are intended as a guide (like a propeller chart). Try a size larger or smaller if in doubt. See "Parts List" for sizes available. 2. No change in spark advance is recommended for elevation operation. Propellers of a lower pitch should be used at high elevations to attain proper engine RPM. attain reasonably smooth idling. Too lean a setting is a major cause of hard starting. 6. When in doubt, it is preferable to have idle mixture set too rich rather than too lean. 7. If engine hesitates during acceleration after adjusting idle mixture, it is too lean, and idle mixture should be richened slightly until the engine accelerates correctly. HIGH SPEED ADJUSTMENT High speed circuit in carburetor is equipped with a main fuel jet (high speed jet) which is changeable but not adjustable. IDLE ADJUSTMENT 1. Idle mixture and idle speed have been set at the factory. Due to local conditions, it may be necessary to readjust the carburetor (in test tank or on boat). (Figure 4) 2. Set idle mixture screw one turn open from lightly seated position. Start engine and allow it to warm up to normal operating temperature in forward gear. NOTE: All carburetor settings must be made in FORWARD GEAR with the engine properly warmed-up. 3. With engine running at idle speed (750 to 800 RPM), slowly turn idle mixture screw a - Idle Mixture Screws (3) b Screwdriver counterclockwise until the affected cylinder starts to load up ("four cycles") or Figure 4. Idle Mixture Adjustment fires unevenly because of an over-rich mixture. 8. Return engine to idle speed and adjust idle 4. Slowly turn idle mixture screw clockwise speed screw so that engine will idle at until the affected cylinder fires evenly and recommended RPM (750 to 800 RPM). engine picks up RPM (approximately one 9. Run engine in forward gear (4000 to 5000 turn from lightly seated position). RPM) to clear crankcase of puddled fuel 5. Do not adjust leaner than necessary to and recheck idle RPM.