Vacumn line Routing & Hard Line between Carb & Dist

[tim71]

I've tried to search forum for answers, but what I've found is all over the board.
Question1: Attached is a picture of the metal pipe that is used between the carb(CEC solenoid) and distributor. Does anyone know or have a photo of how this pipe is attached to the intake manifold?
Question 2: my Rochester 4mv carburetor has 4 vacuum ports. I know the front large port is for the PCV valve. That leaves 3 ports that I'm not quite sure of their proper use. My guess is that the long port on passenger side of carb goes to air cleaner heat snorkel, the port on the front lower left side of carb runs to CEC valve, the remaining port on the upper right side of carb runs to evap cannister over/under the battery. Does anyone know if this is correct or have a photo? Attached is a photo of the front of my carb with black covers on the vacuum ports.Attachment 2001959

I cannot get my photos to load properly, I've tried to get them right side up to no avail.

[Ironangel]

Those are both ported vacuum sources, the long barb on the right side is manifold vacuum. I know this doesn't answer your question but not knowing what year, what options, and the history of the vehicle, there are any number of vacuum line routing options. I tried to rotate your pic but no go for some reason...Your pic shows a TCS system CEC solenoid, there is also an idle stop solenoid, a transmission switch, and a relay under the dash involved with the TCS system. Very complex and unnecessary unless your restoring to factory form. There is a vague diagram in the 72 C/10 service manual under "Emission Control Systems 6T-2". Most including myself have long since did away with TCS and air injection systems. The TCS system was a band aid to satisfy emission standards at the time and were not used long before EGR systems replaced them entirely.

[randy500]

It goes to the black plug under the carb solenoid.
To clarify...the port is below the screw holding te solenoid bracket.

[randy500]

I think this pic is the super low mile 69, shows vac line in a different location than i posted.

[tim71]

Originally Posted by randy500

I think this pic is the super low mile 69, shows vac line in a different location than i posted.

Thank you for photo and info.
Looks like the engine in your photo was pre evap canister engine. The port feeding the distributor in your photo is the port that I believe goes to my CEC valve (which feeds the vac advance on my distributor). The other port on the front of your engine's carb is capped off and I believe it runs to my evap canister on my 71 truck. In your photo, it looks like the long small diameter port on the side of carb is not used or capped? Also,just to compare, the single port fitting behind the carb on your engine looks like it goes to transmission. On my truck, this fitting is a 3 port fitting that feeds the transmission, power brakes and the vacuum reservoir ball (on side of AC housing).

[randy500]

Thats not my truck, its the barn find 69 with 80 original miles.

Post 2 of this thread has a good engine pic, and many other pics.
http://67-72chevytrucks.com/vboard/s...d.php?t=549556

[Metaldoc]

May help I cleaned up the lines to look nicer

[AussieinNC]

Originally Posted by Metaldoc

May help I cleaned up the lines to look nicer

Metaldoc....that is way too purdy to be a worker engine....nice work...!

[Pro299]

Tim71, I went through a lot of old posts trying to answer this same question when I put in a crate motor over the winter. Mine is a 72 C10 350/350. Should be similar to your 71 except mine has only the vacuum line from the distributor can to the carb fitting under the choke. On mine, the canister is labeled for pcv, carb, and fuel tank. That may not be exact because the truck is out in the shop and I'm inside, but if you have a canister with three fittings, they should be marked with something like that.

The consensus seemed to be as follows. The tank connector is on the frame near the fuel line. That's the line that evacuates the fumes from the tank. The pcv line connects with a tee into the pcv line. That line goes into the large fitting on the carb under the fuel filter. That line feeds the fumes from the canister into the intake. The third line goes to the carb fitting on the lower right side in the front. That small line is the one that controls the valve in the canister. That is how I hooked mine up and it seems to work fine.

[tim71]

Originally Posted by Pro299

Tim71, I went through a lot of old posts trying to answer this same question when I put in a crate motor over the winter. Mine is a 72 C10 350/350. Should be similar to your 71 except mine has only the vacuum line from the distributor can to the carb fitting under the choke. On mine, the canister is labeled for pcv, carb, and fuel tank. That may not be exact because the truck is out in the shop and I'm inside, but if you have a canister with three fittings, they should be marked with something like that.

The consensus seemed to be as follows. The tank connector is on the frame near the fuel line. That's the line that evacuates the fumes from the tank. The pcv line connects with a tee into the pcv line. That line goes into the large fitting on the carb under the fuel filter. That line feeds the fumes from the canister into the intake. The third line goes to the carb fitting on the lower right side in the front. That small line is the one that controls the valve in the canister. That is how I hooked mine up and it seems to work fine.

Your vacuum line routing matches what I thought mine should be. The 2 remaining ports on my carb are both full unported vacuum, so it wouldn't really matter which I use for Air cleaner vacuum(temperature sensor that feeds snorkel door) or CEC valve vacuum.
Still looking for a photo of the metal hard line that runs between CEC valve and distributor.

[randy500]

Hard line to tcs solenoid

[randy500]

Another pic.
Hard line inserts into carb vac fitting, very short hose seals it.
Over the fuel line and below the vac fitting on side of carb to tcs solenoid.

[randy500]

This pic looks like the hard line goes over the side vac fitting.
Said to be 20k mile K5

[Happy_dan]

Does this help?

[BT71]

Pic from a stock ‘71. Hope it helps.

[tim71]

Originally Posted by Happy_dan

Does this help?

Thanks, best view of vacuum hard line yet. Only difference is my 71K1500 has the CEC valve that has the ability to turn vacuum to the distributor on and off, thus my hard line runs between the CEC valve and distributor. Very similar though.

[tim71]

Originally Posted by BT71

Pic from a stock ‘71. Hope it helps.

This is probably my set up, looks like I see a CEC valve sticking off the front of the carb. If you have any more photos that are a closer view or some different angles it would help. Thanks, Tim