![]() ![]() Thus the Rochester 4M Quadrajet was born. 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. I now have the canister hose connected to a fitting I added on the air cleaner body, so it draws air into the system if needed, and any vapor/smell just goes into the air cleaner and gets pulled into the carburetor.Īnyone know how that older two port vapor canister worked? Maybe I'm missing a vacuum control valve that was removed long before I got the truck.The "CCC" E4ME Q-Jet is a great dual purpose carburetor, provided it and all of its supporting systems are properly maintained. I have tried connecting it with a T into the PCV hose and it seemed to work fine, but I wasn't sure that I didn't just create a big vacuum leak. My Quadrajet documentation shows the extra front port as a special port for the vacuum canister connection, but there is no explanation of how it works and when it purges the fumes. The stock '75 vapor canister only has two ports and my truck had no separate vacuum valve or check valve controlling the system. When I switched to an 80's Quadrajet I lost that port and it was not clear where to run the vapor canister purge hose. The original Quadrajet in my '75 GMC 350 had a second vacuum port for the evaporative canister, on the lower front of the carburetor next to the large port for the PCV valve hose. I don't think they check anything else.Ĭan I remove or cleanup some of the hoses that route to the canister? I think the one on my Olds is hooked up to ported vac on the carb and that's about it. The clamp off the line marked with the red arrow which is the vapor line from the tank. The truck has to pass an emissions test (sniffer) and they always check the gas tank holds pressure. ![]() The C10 has this crazy set of lines which seem to tee into each other a lot and I get the feeling that not all of those connections are leak free. ![]() My question is, is there anything I can do to simplify some of this? My Olds projects often have just one or two connections to the vac canister, so I feel like something simpler should work. I replaced some of the lines which were shot when I got the truck to try to cut down on vac leaks. They tee into each other so much, it is hard to tell what's going on. I'd like to simplify all of the craziness around the vac lines to the evap canister. So I finally had some time and was working on my C10 (1985, 305, TH-350C). ![]()
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