The Rich and Lean Stops limit the travel of the main Metering Rods. The TPS sends signals to the computer and tells it where the throttle is positioned. In Closed Loop, the computer moves the MCS up & down to achieve the ideal 14.7 Air/Fuel Ratio. The TPS sends electronic signals to the ECM, then based on the various sensor info, the ECM sends varying signals to the MCS within the carburetor, controlling the depth of the primary metering rods in their jets, richening or leaning the mixture based on engine load. These carbs use a Mixture Control Solenoid (MCS) & a Throttle Position Sensor (TPS). The CCC's Electronic Control Module (ECM) monitors several engine parameters under normal operating conditions and utilizes an oxygen sensor in the driver's side exhaust manifold to measure those adjustments. The Quadrajet was simply redesigned to accept electronic internal components, offering more precise metering of the primaries, reducing emissions, and improving fuel economy at part open throttle. The E4ME did its job so well that Ford, Chrysler, and AMC all bought them from GM to use on some of their higher output engines of the time. Until GM's Rochester Division could create reliable fuel injection systems, it was really a very simple solution to Federal Emissions mandates. There are a lot of myths surrounding the E4ME version of the Q-jet. With only a few special exceptions, these carbs were primarily calibrated for economy and emissions, not high performance applications, yet most of the limitations are easily undone. The primary bore was typically 1 3/32 inches and the secondary air valve opening was limited to 70 deg, not 90 degrees. In 1981, the Q-jet was modified to the E4ME specs to meet the ever increasing demands of the Federal Emissions mandates. In 1975, GM changed the Q-jet to meet more stringent smog requirements and designated it the M4M. During the late 60's/early 70's, Federal Emissions mandates caused GM to force its divisions to use the Q-Jet as their only 4 barrel carb. (Carter had no involvement in the design). Due to ever increasing demand by the various GM brands for their ever larger V8's, GM turned to Carter to produce Q-jets for GM, thus creating the "Quadrajet by Carter" used on the sides of some 60's versions. Thus the Rochester 4M Quadrajet was born.
1977 el camino emission vacuum with quadrajet full#
Facing thousands of reliabilty complaints and engine failures due to gasoline wash, GM set its engineers out to design a carburetor that could work reliably in all conditions, have reasonable mileage, give excellent full throttle capability, and work atop just about any engine for all kinds of applications. Originally, GM used Holley & Carter carburetors on many of its 60's V8 engines, but those weren't very reliable for everyday driving. Nay-sayers use terms such as "Quadra-bog", "Crap-jet", etc, however the Q-jet is, in most respects, the best carburetor ever designed. Add in any number other things that need to be replaced and you've got a dead horse, so stop kicking it, get off your ass, and go fix it. If your car has 120,000 miles and the TPS is full of oil sludge, the MCS is unplugged, and the choke is bad, don't be suprised if your car reeks of gas & moves like a snail. The number one source of problems for these carbs has been vacumn leaks through the throttle shafts due to wear. Age, heat cycling, gasoline, and wear all contribute to failure. As with anything, if its not taken care of, it won't be reliable. Many times, I've heard/read people complain about these carbs sucking and never running right. ROUND BLACK/ GREEN/ GRAY, Aluminum/Plastic Case w/ Blade Connector: (pass-side) Electric Choke
WHITE/ BLACK/CLEAR/ YELLOWED/ GRAY Female Connector: (front driver's-side) Throttle Position Sensor In stock form, the E4ME has several things that limit it, but they are easily undone with a few simple mods, common tools, and easy to find parts.īLUE /BLACK Female Connector: (top-front pass-side) Idle Mixture Control Solenoid GM proved its full capabilities during testing of its Emissions Legal ZZ3/ZZ4 350 conversion package for 1982 - '87 LG4 and L69 Camaros and Firebirds, (discontinued). These carbs can easily support up to 450hp, provided it is kept clean, maintained, and its related systems are intact and funtioning properly. On the flip side, if you "Open it Up", the E4ME Q-Jet's secondaries were designed to reliably flow up to 750 CFM Wide Open Throttle. It was designed to work in a wide variety of enviromental conditions, provide excellent daily reliability, and still provide good gas mileage. The "CCC" E4ME Q-Jet is a great dual purpose carburetor, provided it and all of its supporting systems are properly maintained.
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