1977 el camino emission vacuum with quadrajet

#1977 el camino emission vacuum with quadrajet drivers

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. However, the vacuum connection to the carburetor should be switched from the 'J' port below the fuel nut to the 'B' port above the fuel nut.So I finally had some time and was working on my C10 (1985, 305, TH-350C). It appears that the delay valve is correctly connected to the 4-port TVS and distributor. Again, orientation of the delay valve color coding is important. The distributor vacuum advance connects to the 4-port TVS through a black and white plastic 4-port delay valve, labeled 'DISTR DELAY VALVE' on the diagram. The EFE valve is basically a vacuum operated exhaust heat riser for rapid intake manifold heating and improved fuel atomization during cold weather operation. The second hose down from the top of the 4-port TVS routes to the EFE (Early Fuel Evaporation) valve through a 5/32' steel pipe, adjacent to the EFE valve located at the outlet of the right exhaust manifold. The 'black' side of the check valve should be plumbed toward the intake manifold vacuum fitting just pictured. The orientation of the check valve is important. Note that there should be a small plastic check valve in the upper vacuum hose attached to the 4-port TVS. The fitting pictured below is the source for the manifold vacuum and is labeled 'MANIF VAC SOURCE' on your vacuum diagram. The tip-in switch should be plumbed directly to manifold vacuum along with the thermostatic air cleaner (TAC) and the upper port of the 4-port TVS through two vacuum tees. The tip-in switch appears to be incorrectly plumbed on your truck. It's purpose is to help minimize cylinder detonation and associated engine damage. The 'tip-in switch' monitors manifold vacuum (aka, engine load) to allow for an immediate decrease in ignition timing when the throttle is rapidly opened. The device imaged below is called a 'Tip-In Vacuum Switch.' It is part of the Electronic Spark Control (ESC) system. The upper vacuum hose from the 2-port TVS connects to a vacuum 'tee' that splits the vacuum signal between the EGR valve located just to the right (passenger) side of the carburetor and a second vacuum 'tee' that splits the signal again between the TCC vacuum switch located on the firewall (imaged below left) and the rightmost 5/32' purge nipple on the vapor canister (as imaged, below right).įollow along by referring to the diagram as we continue. The short vacuum hose from the bottom port of the 2-port TVS connects directly to the carburetor 'J' port. The 'J' vacuum port is the 5/32' port physically located below the fuel inlet nut, near the right (passenger side) idle mixture screw in the following image. 'B' should be the 5/32' manifold vacuum source located above the fuel inlet nut, 'L' is the 3/8' PCV vacuum port located in the front of the throttle plate below the fuel inlet nut, and 'T' is the 3/8' bowl vent exiting the fuel bowl cover. Some of the vacuum ports on the carburetor will be marked with an upper case letter cast into the carburetor body adjacent to the ports. I'll respond to your question in stages, as time permits. (the heads a little foggier since Afghanistan, So my apologies beforehand to any keyboard warriors out there) The diagram on the Rad support is there and I`ve tried to follow it but I`m not sure if I have the pieces it say's I need or quite understand it.

#1977 el camino emission vacuum with quadrajet drivers

I have the Vacuum Canister, EGR, Vacuum Advance, PCV, 2 and 4 Port Vacuum Switch, There is another Diaphragm on the left side (as if sitting in drivers seat) at the front on the carb that I`m not sure to what it is. The engine is coming out in the next 6-9 Months and I do not do a whole lot of driving, So not to worried if I loose or gain any MPG. My truck is a 1986 C10 2wd, Auto, 305, 700R4, Rochester QuadraJet Carb, Headers, Dual Exhaust. I`m not sure what ports those plugged lines went to. Some of the lines were plugged already by the previous owner. I would prefer to get all original lines connected as much as possible. So now I am in the process of putting things back together. I did'nt mark my vacuum lines when I did the Head Gaskets