| Below is a list of articles with the most recent ones listed first. |
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QUADRAJET Carburetor Models 4MV-4MC-M4ME-M4MC Service Manual |
Topic: Rochester |
| QUADRAJET Carburetor Models 4MV-4MC-M4ME-M4MC Service Manual |
| Published: Sunday 01 October, 2006 |
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Rochester - COMBINATION EMISSION CONTROL (C.E.C.) VALVE |
Topic: Rochester |
| On some 4MV Quadrajet applications, a carburetor mounted Combination Emission Control (C.E.C.) valve is added to help reduce exhaust emissions (Figure 38). A vacuum tube in the float bowl is connected by hose to the C.E.C. valve which, when energized by a transmission signal, controls distributor v... |
| Published: Saturday 30 September, 2006 |
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Rochester - CHOKE SYSTEM – 4MC (LATE) |
Topic: Rochester |
| The choke housing on late model 4MC carburetors (Figure 35) is also located on the float bowl, but with a separately mounted vacuum break diaphragm unit. The vacuum diaphragm unit on some 4MC models includes and internal delay valve for good control of choke mixtures during the engine warm-up perio... |
| Published: Saturday 30 September, 2006 |
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Rochester -CHOKE SYSTEM WITH DUAL DELAYED VACUUM BREAK SYSTEM |
Topic: Rochester |
| Other Quadrajet carburetors use a dual delayed vacuum break system consisting of front and rear vacuum break diaphragm units (Figure 33).
The dual delayed vacuum break system operates as follows:
During engine cranking, the choke valve is held closed by the tension of the thermostatic coil. Th... |
| Published: Saturday 30 September, 2006 |
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Rochester -CHOKE SYSTEM WITH VACUUM BREAK CLOSING ASSIST SPRING |
Topic: Rochester |
| Other 4MV models have the choke closing assist spring located on the vacuum break plunger stem replacing the torsion spring located on the intermediate choke shaft (Figure 30).
The choke closing assist spring aids in closing the choke valve along with tension from the remote choke thermostatic co... |
| Published: Saturday 30 September, 2006 |
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Rochester - SECONDARY THROTTLE VALVE LOCKOUT |
Topic: Rochester |
| A secondary throttle valve lockout feature is used on many Quadrajet models to prevent opening of the secondary throttle valves during cold operation when wide open accelerations could cause possible engine damage or excessive wear (Figure 27). On these applications, a lockout lever, located on the... |
| Published: Saturday 30 September, 2006 |
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Rochester - AIR VALVE DASHPOT |
Topic: Rochester |
| The secondary air valves use an air valve dashpot feature to control opening rate of the air valve. This prevents an uncontrolled air valve opening rate which results in an instantaneous air rate change and a “lagging” fuel rate change as the secondary throttle valves are opened. The dashpot, thro... |
| Published: Saturday 30 September, 2006 |
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Rochester - MULTIPLE STAGE POWER ENRICHMENT |
Topic: Rochester |
| In some “modified” Quadrajet carburetors, a multiple stage power enrichment system, consisting of two power pistons (Figure 21), is used for more sensitive control of air/fuel ratios during light duty engine power requirements while providing for richer mixtures during moderate to heavy engine loads... |
| Published: Saturday 30 September, 2006 |
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Rochester - ADJUSTABLE PART THROTTLE FEATURE |
Topic: Rochester |
| On “modified” Quadrajet carburetors that use separated main wells, the A.P.T. adjustment consists of a pin pressed in the side of the power piston which extends through a slot in the side of the piston well. When the power piston is down (economy position), the pin stops on top of a flat surface of... |
| Published: Saturday 30 September, 2006 |
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Rochester -MAIN METERING SYSTEM M4MC-M4ME MODELS |
Topic: Rochester |
| Starting in the 1975 model year, major casting changes were made to the air horn, float bowl, and throttle body of the Quadrajet carburetor to incorporate a new Adjustable Part Throttle (A.P.T.) feature and, on some applications, the addition of an auxiliary power piston and metering rod assembly. ... |
| Published: Saturday 30 September, 2006 |
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