Usage:
Introduction
A line pressure regulator is required on turbocharged and aftercooled engines. In addition, naturally aspirated engines with a gas supply pressure exceeding the inlet pressure differential between the gas and air must use a regulator.
Operation
Gas flows through inlet (12) (Fig. 1), orifice (6), past valve disc (5) and through outlet (4). Lower chamber (8) senses outlet pressure.
FIG. 1. REGULATOR OPERATION
1-Upper chamber. 2-Adjusting screw. 3-Spring. 4-Outlet. 5-Valve disc. 6-Orifice. 7-Diaphragm assembly. 8-Lower chamber. 9-Lever. 10-Pin. 11-Valve stem. 12-Inlet. A-Vent valve.
As gas pressure in lower chamber increases to a value higher than the force of spring (3) and air pressure in upper chamber (1) (atmosphere on naturally aspirated engines and turbocharger boost on turbocharged engines), diaphragm assembly (7) is forced upward. This pivots lever (9) about pin (10) and causes valve stem (11) to move valve disc (5) to close inlet orifice (6).
FIG. 2. DETAIL A-VENT VALVE OPERATION
13-Upper flapper. 14-Orifice. 15-Orifice plate. 16-Lower flapper. 17-Springs (two).
As diaphragm assembly (7) is forced upward, air is expelled from the upper chamber (Fig. 2). This movement of air forces lower flapper (16) upward, carrying upper flapper (13) with it. The trapped air is permitted to escape. This is accomplished quickly enough to prevent any lag in the main diaphragm assembly movement due to air compression.
With orifice (6) closed (Fig. 1), gas is pulled from lower chamber (8) through outlet (4). This reduces the pressure in the lower chamber. As this pressure becomes less than that in the upper chamber, spring (3) and the air pressure in the upper chamber forces diaphragm assembly downward. This opens orifice (6) and allows additional gas flow to the regulator.
As diaphragm assembly (7) moves downward, air rushes inward to fill the partial vacuum created in the upper chamber (Fig. 2). This forces upper flapper (13) down against orifice plate (15). Air going through webs in upper flapper opens lower flapper (16) and fills upper chamber.
When the pressures above and below the diaphragm assembly are equal, the regulator supplies gas to the carburetor at a constant pressure differential above the incoming air. Orifice (14) allows passage of air when pressure changes on either side of diaphragm assembly are not sufficient to overcome spring (17). The regulator is adjusted by turning adjusting screw (2). See the topic, AIR INDUCTION AND EXHAUST SYSTEM.
Disassembly And Assembly
PREPARING TO DISASSEMBLE REGULATOR
1-Cap. 2-Adjusting screw. 3-Spring casing.
NOTE: Later regulators use a solid adjusting screw (2) (that is, no center hole).
NOTE: Later regulators have two plates (6), one on each side of diaphragm (4).
REMOVING DIAPHRAGM
4-Diaphragm. 5-Spring.
DISASSEMBLING DIAPHRAGM
4-Diaphragm. 6-Plate. 7-Spring seat and bolt. 8-Post.
DISASSEMBLING DIAPHRAGM CASING
9-Valve body. 10-Screws (two). 11-Pin. 12-Bolts (two). 13-Rotating flange. 14-Lever.
DISASSEMBLING DIAPHRAGM CASING
11-Pin. 14-Lever. 15-Valve disc. 16-Valve disc holder. 17-Seal. 18-Valve stem.
NOTE: During assembly, the casing can be rotated to any position relative to valve body (9). Install bolts (12) through valve body into rotating flange (13). Position casing and tighten bolts.
NOTE: Valve disc holder (16) is threaded into valve stem (18).
REMOVING ORIFICE
9-Valve body. 19-Orifice.
NOTE: Orifice (19) and valve disc (15) can be replaced without removing valve body (9) from the line or breaking any pipe connections.
DISASSEMBLING SPRING CASING
20-Screws (three). 21-Screw.
DISASSEMBLING VENT VALVE
21-Screw. 22-Spring. 23-Lower flapper. 24-Orifice plate. 25-Upper flapper. 26-Spring.
Inspect all parts.