Vacum canister

[sand rocket]

Can anyone tell me what vacum lines go were on the vacum canister or Fuel Vapor Canister what ever it is called. I need to get them hooked up for an emisions test. It is a 79 c-10. i have searched but have had no luck. Any help would be apreciated. thanks

[menace121978]

welcome to the board man

if im not mistaken... clean off the top and look real close. i think they are somewhat labeled. pics would help us help too

[sand rocket]

I cleaned the top of the canister off. These are the best pics i could get. The one for the fuel tank was already hooked up. There are two lines per side. One side is carb bowl and the other is pvc im thinking.
With there being one big and one small on each one, are the t together?

[sand rocket]

anyone?

[54Caddy]

i will post a picture if photobucket lets me. I need to know more about the truck. What size engine and is it a 4 barrel or 2 barrel carburetor. i have an original gm shop manual for 79s its your lucky day

[sand rocket]

350 with a edlbrock 1406

[menace121978]

the big ones are pcv- fuel tank- carb bowl.(left to right)

the top small ones should be labeled mainfold vaccum.

[sand rocket]

where do they go on the carb though? Im sorry i have never worked on american motors before. I can figure out the one that goes to the pcv but have no idea on the rest. The fuel tank one is hooked up already. On the carb the distrbuter is hooked up to the passenger side port. The center one is ran to the pvc valve. The driver side port is kaped.

[menace121978]

you will need a T for the pcv. and the manifold vaccum ports can be T'ed at the canister and run to the capped port on the carb. mine went to a valve on the intake manifold but on yours the carb will work.

[54Caddy]

will get a picture up here in a bit. I dont know if it will help you much since you now have an edelbrock but maybe it will

[redneckchevy]

I am working on a '86 C-10 puting a 350 with an edelbrock intake and carb on it. i am running no PCV valve. mine is hooked up to the gas tank, but do i need to hook the rest of them up? or can i plug them or just leave them open? right now the one's for the pcv and all the are open.

[leegrady]

Ah, fuel evaporation. I just love the smell of them motors. The EPA guy didn't want the vapors stored in the charcoal canister to be burned until the engine is at operating temp. So the vacuum line goes to a coolant temp switch screwed into the intake manifold, it wont let vacuum through until it reaches a set temp. From Manifold absolute pressure (not ported) vacuum runs to the temp switch then to the top smaller vacuum fittings on the canister. This will open the valve to purge the vapors.
Vapor go in at the "bowl" and "fuel tank" fittings, and go out to be burned from the "PCV". This is a basic description. Vacuum configurations will vary from year, make, model, but this is basically how it works. Check manufacture spec' sheets, (factory manuals are the best source).
EGR valves have similar configurations, but ported vacuum not MAP. The EGR valve cannot operate at idle. The dilution of air/fuel charge will make the engine stall at idle. EGR valves cool combustion temps to stop the production of NOx which produces tropospheric ozone, better known as "smog". But I digress.
(Note too some charcoal canisters have a round filter located on the bottom that needs to be replaced upon normal service schedules.)
Good luck, and watch for leaks.

[Panelman55]

What about putting the canister in the round file and not using one at all. The EPA is also the group that told us about "GLOBAL WARMING" if I remember correctly. My brother removed the canister on his truck, just after it filled the float bowl with some of the finest charcoal I've ever seen. It ran better after that. He took it to the drags every weekend and ran in the low 10's with a stock, less the smog stuff, 305.

[sand rocket]

I called and talked with an emisions tech. He seemed like a good guy on the phone. He told me that, if the truck is going to be registerd in are county that it need the smog equipment, but being a 79 it can fail the tampering inspection for emisions and still pass overall emisions with the tailpipe test. The tampering inspection is the visual to make sure that its there. So im good. Just need to get the tailpipe test.