I've wrenched on a lot of Chevy trucks, but this is my first GM car project. My son and I are working on a 72 crew cab Skylark that will be his first car. I'm finding things I don't recognize. Some of the issues fall under the infamous previous owner curse. FWIW, this is a 350/TH350 drivetrain. Factory AC. QUESTION #1 We just put a 4bbl intake on the 350 and just about every vacuum line had a tee with 1 side capped. We have the easy stuff figured; pcv, brake booster, vac advance, and trans. We also figured out one of the capped tees should have been connected to the evap canister. Another capped tee I thought should be connected to this do-dad on the firewall that I believe works with the climate controls. There is a hose that runs into the cabin and the other port was open. I connected the open port to manifold vacuum off the carb but then later I found a second hose coming from the cabin with a white line on it. Should I have manifold vacuum connected to that pod? What is the white striped hose coming from the cabin supposed to be connected to? QUESTION #2 The engine harness has been re-loomed. I hope it was just cleanup and not because of an electrical issue. I happened to notice this splice: I don't think this seems factory. All 4 wires are heavy gauge, 10-12ga. This is in the harness running down the passenger valve cover. Any ideas what these are for?
Factory splice. Two power supply from the starter with two fuse links. Just need to wrap it properly. And verify the two fuse links are in line down by the starter. Someone here should be able to post a pic of the vacuum canister hose routing.
Thanks! I'll wrap that up. I wish I could get some heat shrink on it but I'm not ambitious enough to pull the harness off far enough to accomplish that. Is that vacuum canister part of the climate controls? I have a service manual I could look up the drawings in, I just didn't know where to start.
The manual is excellent for hose routing. Open it and study what is connected. Once it makes sense take it out to the car and see what is already connected correctly, and then one thing at a time. Use tape and flag things as you go, so you can ignore them.
I realized what the hose is for, the valve in the heater hose. I held the hose out and figured out what was in the range of its reach.
Big round thing is the vacuum canister. It is necessary to run all the climate control vacuum switches that change from heat/defrost/ac, etc. Thing on the heater hose is the bypass valve... bypasses hot water from circulating into the heater core when you switch on the AC, I believe that it has a vacuum hose with a white line on it.
That explains why the only place air blew out was the heater vents. Never would get air out the dash vents no matter what we selected. With that vacuum canister hooked up, that should change.
Bunch of lines vent from the gas tank to this. You have to get under the car to see the lines going from the gas tank to this doo-hickey. Should have rubber hoses attached to the bottom of this that you can't see inside the car.
