Hey guys, While the alternator is pulled I figured I would take some time to check out the evap/vacuum system in the car. It's a 1978 GTB. Prior to my ownership, the air pump was removed. The flapper system was also removed. I then welded up the air injector holes when I removed the headers for ceramic coating. I started with this thread, which was great, but doesn't exactly address the questions in my system. After going through a few things, it turns out that the PO had sealed up the charcoal canister with some gasket maker. The lines throughout the car need to be replaced, but everything going through that system is very worn. I have removed the canister, valve thing and lines. Image Unavailable, Please Login When I removed the Y connector going to the carbs, I noticed that the vacuum coming off the body of the fourth carb was completely open. I'm going to guess this is a mistake probably related to the missing flapper valve? Image Unavailable, Please Login When driving the car, the engine would pretty regularly make a very noticeable "TICK" sound coming from the intake... I'm wondering if this was related to a possible baby backfire? The plan is to R&R the carbs later this summer, but would love any input. As for the proper approach, should I just cap off all these opening with some high temp silicon caps? One other thing that looks a little fishy to me is on the driver side of the engine as well. Could someone tell me the function of this large valve? It appears to be pulling vacuum and then splits into the air box. Is this a crankcase breather regulator or some other component related to the air system? Image Unavailable, Please Login Thank you for any references or pointers!
You are correct, there should not be any open vacuum lines, including to the fourth carb. The canister in the last picture is the crankcase breather separator, it separates out residual oil from the crankcase fumes, and allows oil to drain back to the crankcase. The crankcase air (hopefully sans oil) is then routed to the carb intake air box.
You can't just remove all of the fuel evaporation control system off of a US version and cap everything off -- they have a closed gas tank system so you need to provide a vent somewhere to let air enter and exit the tanks. At a minimum, you should run the hose (item #28 on TAV 11 of your 161/78 SPC) connected to the top of the fuel/vapor separator (item #22 on TAV 11 of your 161/78 SPC) in the RH C-pillar down to be well below the bottom of the gas tanks and leave it open to the atmosphere (by extending the open end of the hose to be down below the whole fuel system, no liquid fuel will come out if the coachwork is upside-down). Good luck (I was never here )...
@Steve Magnusson thanks Steve, that is pretty much exactly what I did. There was SO MUCH excess fuel line once the canister was removed that I routed it up and around the wheel well and out the back at the bottom near the coolant overflow drain. Thank you for the tip, for sure something to watch out for!
I always read that the vacuum canister connected to a pipe near the rear bank of carbs was essential. The line from the front bank of carbs has always been blocked off. I was cleaning up hose ends and clamps today, and was astonished to learn that that hose from the back side into the big plastic tank has been blocked inside for the 31 years that I have owned the car, without negative results. The oil separator on the left side of the engine was blocked with oil sludge, and the inside of my air cleaner box was an oily mess, but the car runs very well. I cleaned the separator and am going to try a small UNI filter on the outlet of the oil separator, giving the air cleaner box a break. I will report back later. My last inquiry is about crankcase pressure. My engine oil cap has a good seal, but still allows small amounts of oil to run down that valve cover. Any advice would be appreciated.
