Getting rid of smog equipment - The 1947 - Present Chevrolet & GMC Truck Message Board Network

*vegaschevy* · 08-21-2009, 01:02 PM

I have a 72 350 truck. Im sure some of you are tired of my ignorant questions but I am learning as I go along. I am to the point of reassembly of my intake and carb I purchased and want to get rid of all the smog equipment.

From the canister I have a couple lines that go down into that area. They are not hooked up to the smog canister though. I believe they went to a valve on the stock manifold. The manifold has a vacuum type port thread into the passenger side of the manifold. it has two 1/4" or 5/16" ports on it. One def went to the smog canister. The other I am not sure where it went to. Anyone know? Or can you help me? Also the canister has a tube that goes to the front drivers side valve cover, I think I can just plug that with no problems.

Then out the bottom of the canister there is a line that appears to go down to the hard line along the frame. Where does this go and what can I do with that?

Thanks for all your help, I can get you any pictures if needed.

mclairmo · 08-21-2009, 01:22 PM

I would just remove all the lines and canister and plug everything up. However, the gas tank may then start to vent fumes into the cab, from what I've read.

*vegaschevy* · 08-21-2009, 01:27 PM

Some of the lines were just dangling there. THat is why I am trying to figure out if I can just get rid of some of this stuff or what can be gotten rid of completely. Plugging lines only masks what I am trying to do especially when the canister comes out so easily.

**john** · 08-21-2009, 01:44 PM

The vacuum solenoid on your manifold is for TCS (transmission controlled spark) which can be discarded. It only allows vacuum advance in high gear. You should find a relay and wiring to trans that goes with it.

*vegaschevy* · 08-21-2009, 01:58 PM

Quote:

Originally Posted by john

The vacuum solenoid on your manifold is for TCS (transmission controlled spark) which can be discarded. It only allows vacuum advance in high gear. You should find a relay and wiring to trans that goes with it.

So the vacuum port on the dizzy is part of that? I was thinking that is where that went?

Ill have to get some more pics of everything once I get closer tomorrow of getting the carb on and everything.

I just cannot figure out where everything else goes. Maybe Ill go take pics for everyone real quick. Then we can go through them one by one. LOL

*vegaschevy* · 08-21-2009, 02:06 PM

Ok check back shortly, I am downloading pics of ports, line etc.

*vegaschevy* · 08-21-2009, 02:35 PM

Ok here are some pics,

I want to get rid of the tall filler neck, and the front vent as it appears to go to the smog stuff. ALso in this pic is the vent from the drivers side manifold. Can that be just taken off?

These next two pics are for the front two ports on the front of the manifold. The passenger side one in the second pic gets a fitting and goes to the heater box I believe.
The one on the drivers side I ahve no idea? maybe I can plug it.

This next pic shows the port in the rear of the manifold. What goes in it? The fitting in the second pic? I think so, what goes to this fitting?

I believe this is the sensor someone said to just get rid of all together. Is this correct? part of the TCS solenoid?

THe line along the frame from rubber to steel, comes out of the bottom of the charcoal canister which will be removed from the truck. Where does that line go? can it be blocked? removed? left open?

This comes off my heater assembly. what is the line with the screw? why is it plugged?

What does this do? its unhooked, im sure I can pry it back properly. Any ideas?

The line coming out of the brake booster, originally threaded into the rear of the carb, no provision I believe on the new carb. Where would it now go?

*vegaschevy* · 08-21-2009, 02:36 PM

This line comes off the rear of the motor somewhere, where does it go? what does it do?

**leddzepp** · 08-21-2009, 03:50 PM

Your third pic, from the bottom up, is the cowl vent control. This shuts off the outside airflow when the A/C is on. You need to run a vacuum line to this actuator. It shuts when the A/C is on, opens when the heater is on, A/C off.

The pic above that is your heater shutoff valve. That needs to be closed when the A/C is on, prevents the heater core from heating up. Some had 2 vacuum nipples on them. Only one of them actually works. I would guess that the plugged line is connected to the nipple that doesn't work. You can probably just pull that line off.

Your very first pic is the heat riser tube, not a filler tube. You can pull the tube, and the "stove" on the exhaust manifold and sell those. People looking to restore a truck to original are always looking for this setup.

**john** · 08-21-2009, 03:52 PM

If there is no vacuum port on the carb you can use a fitting like this http://www.corvette-paragon.com/p-35...m-fitting.aspx and use a brake booster hose instead of the tube. The other small hose from your trans modulator (last pic) will plug on the small nipple. Heres a vacuum diagram for your a/c hoses.

*vegaschevy* · 08-21-2009, 04:11 PM

Quote:

Originally Posted by leddzepp

Your third pic, from the bottom up, is the cowl vent control. This shuts off the outside airflow when the A/C is on. You need to run a vacuum line to this actuator. It shuts when the A/C is on, opens when the heater is on, A/C off.

The pic above that is your heater shutoff valve. That needs to be closed when the A/C is on, prevents the heater core from heating up. Some had 2 vacuum nipples on them. Only one of them actually works. I would guess that the plugged line is connected to the nipple that doesn't work. You can probably just pull that line off.

Your very first pic is the heat riser tube, not a filler tube. You can pull the tube, and the "stove" on the exhaust manifold and sell those. People looking to restore a truck to original are always looking for this setup.

Ya I knew the exhaust piece was the stove, I can remove it all together then? great!!

THe oil filler neck sticks up about 10" as well and has a support to the intake manifold, if I get rid of it all together what can I do? buy a press in filler plug?

Ill fix the cowl vent piece and remove the tube with the nail in it. perfect.

*vegaschevy* · 08-21-2009, 04:16 PM

Quote:

Originally Posted by john

If there is no vacuum port on the carb you can use a fitting like this http://www.corvette-paragon.com/p-35...m-fitting.aspx and use a brake booster hose instead of the tube. The other small hose from your trans modulator (last pic) will plug on the small nipple. Heres a vacuum diagram for your a/c hoses.

With getting rid of the electrical tranny stuff will I not need that vacuum port to the tranny anymore in the last pic? can i plug it off at the tranny?

**leddzepp** · 08-21-2009, 05:14 PM

Quote:

Originally Posted by vegaschevy

Ya I knew the exhaust piece was the stove, I can remove it all together then? great!!

THe oil filler neck sticks up about 10" as well and has a support to the intake manifold, if I get rid of it all together what can I do? buy a press in filler plug?

Ill fix the cowl vent piece and remove the tube with the nail in it. perfect.

Yep, you can also sell the filler tube, and just buy a press-in plug.
Just make sure which nipple on the heater switch actually controls it, and which is just an extra "stud" so to speak.

Sinister · 08-21-2009, 05:21 PM

Quote:

Originally Posted by vegaschevy

With getting rid of the electrical tranny stuff will I not need that vacuum port to the tranny anymore in the last pic? can i plug it off at the tranny?

You'll need that vacuum line going to the tranny hooked up to manifold vacuum. Tranny won't shift right without it.

*vegaschevy* · 08-21-2009, 05:26 PM

Quote:

Originally Posted by Sinister

You'll need that vacuum line going to the tranny hooked up to manifold vacuum. Tranny won't shift right without it.

So the TCS can go and the wiring but not the vacuum line.....

Sinister · 08-21-2009, 05:30 PM

Quote:

Originally Posted by vegaschevy

So the TCS can go and the wiring but not the vacuum line.....

Right.

BLACK AND BLUE 67-72 · 08-21-2009, 05:36 PM

The line off of rear of motor, transmission modulator, front drivers side plug it, can be used for heater hose, but use the pass side front, port in rear use for modulator valve, and you can hook up brake booster here also unless you want to use the one in the back of the carb base. And you can remove the pipe for the air cleaner too, tcs solenoid also, line by frame plug it, it goes up into cab near pass side next to fuel line. Heater valve I am unsure where the line goes, and the valve on firewall is for your a/c which I assume does not work anyway. I hope this helps!!!!

*vegaschevy* · 08-21-2009, 06:15 PM

Quote:

Originally Posted by BLACK AND BLUE 67-72

The line off of rear of motor, transmission modulator, front drivers side plug it, can be used for heater hose, but use the pass side front, port in rear use for modulator valve, and you can hook up brake booster here also unless you want to use the one in the back of the carb base. And you can remove the pipe for the air cleaner too, tcs solenoid also, line by frame plug it, it goes up into cab near pass side next to fuel line. Heater valve I am unsure where the line goes, and the valve on firewall is for your a/c which I assume does not work anyway. I hope this helps!!!!

that was a mouthful. LOL

I got most of it. What is the Modulator valve?

I do not think the carb base has a port for the brake booster as I am going with a summit carb (holley)
AC actually works just not on high, So Ill fix the pin in the arm and it should work better. LOL

anything else I miss?

unclewatts · 08-21-2009, 09:08 PM

Quote:

Originally Posted by vegaschevy

Ok here are some pics,
THe line along the frame from rubber to steel, comes out of the bottom of the charcoal canister which will be removed from the truck. Where does that line go? can it be blocked? removed? left open?

That is your EEC or Evaporative Emissions Control line which goes to your gas tank. It should be removed at the tank end and plugged otherwise you will smell gas fumes in the cab especially when the tank is full. Also, you should change to a vented gas cap otherwise you will get vacuum problems. Just my $.02

BLACK AND BLUE 67-72 · 08-23-2009, 09:58 PM

The Modulator valve is located on the passenger side of your transmission, if you have a Turbo 400 it will be on the side, if you have a Turbo 350 it is toward the rear of the passenger side. The Modulator valve controls shifting, you should be able to see the metal line coming from the rear of the motor down the side of the transmission.

BLACK AND BLUE 67-72 · 08-23-2009, 10:03 PM

Also if your carb does not have the provision for the brake booster then you can use the fitting in your hand in the pic, just hook it up to one side and your modulator valve line to the other.

*vegaschevy* · 08-23-2009, 10:38 PM

Quote:

Originally Posted by unclewatts

That is your EEC or Evaporative Emissions Control line which goes to your gas tank. It should be removed at the tank end and plugged otherwise you will smell gas fumes in the cab especially when the tank is full. Also, you should change to a vented gas cap otherwise you will get vacuum problems. Just my $.02

Going to try and find the fittings tomorrow to get all the stuff replumbed

*vegaschevy* · 09-03-2009, 11:22 AM

I got everything else hooked up but still have not removed the transmission solenoid thing that hooks to vacuum. Also have not hooked up the vacuum line off the back of the motor that goes to the transmission.

The tranny solenoid I can unplug, do theh wires need to be jumped or can i leave it unplugged?

Also the vecuum line for the tranny can I just hook it to manifold pressure? the port on the passenger side rear of the motor?

08-21-2009, 01:02 PM	#1
vegaschevy Account Suspended Join Date: May 2009 Location: las vegas nv Posts: 1,493	Getting rid of smog equipment I have a 72 350 truck. Im sure some of you are tired of my ignorant questions but I am learning as I go along. I am to the point of reassembly of my intake and carb I purchased and want to get rid of all the smog equipment. From the canister I have a couple lines that go down into that area. They are not hooked up to the smog canister though. I believe they went to a valve on the stock manifold. The manifold has a vacuum type port thread into the passenger side of the manifold. it has two 1/4" or 5/16" ports on it. One def went to the smog canister. The other I am not sure where it went to. Anyone know? Or can you help me? Also the canister has a tube that goes to the front drivers side valve cover, I think I can just plug that with no problems. Then out the bottom of the canister there is a line that appears to go down to the hard line along the frame. Where does this go and what can I do with that? Thanks for all your help, I can get you any pictures if needed. Last edited by vegaschevy; 08-21-2009 at 01:29 PM.

08-21-2009, 01:22 PM	#2
mclairmo Registered User Join Date: Jan 2006 Location: Take Off Posts: 1,908	Re: Getting rid of smog equipment I would just remove all the lines and canister and plug everything up. However, the gas tank may then start to vent fumes into the cab, from what I've read.

08-21-2009, 01:27 PM	#3
vegaschevy Account Suspended Join Date: May 2009 Location: las vegas nv Posts: 1,493	Re: Getting rid of smog equipment Some of the lines were just dangling there. THat is why I am trying to figure out if I can just get rid of some of this stuff or what can be gotten rid of completely. Plugging lines only masks what I am trying to do especially when the canister comes out so easily.

08-21-2009, 01:44 PM	#4
john member #16 Join Date: Dec 1999 Location: Yuba City Ca. Posts: 3,618	Re: Getting rid of smog equipment The vacuum solenoid on your manifold is for TCS (transmission controlled spark) which can be discarded. It only allows vacuum advance in high gear. You should find a relay and wiring to trans that goes with it. __________________ john http://67-72chevytrucks.com/vboard/showgroups.php board vendors http://www.flickr.com/photos/1745471...7602865984234/

08-21-2009, 02:06 PM	#6
vegaschevy Account Suspended Join Date: May 2009 Location: las vegas nv Posts: 1,493	Re: Getting rid of smog equipment Ok check back shortly, I am downloading pics of ports, line etc.

08-21-2009, 02:35 PM	#7
vegaschevy Account Suspended Join Date: May 2009 Location: las vegas nv Posts: 1,493	Re: Getting rid of smog equipment Ok here are some pics, I want to get rid of the tall filler neck, and the front vent as it appears to go to the smog stuff. ALso in this pic is the vent from the drivers side manifold. Can that be just taken off? These next two pics are for the front two ports on the front of the manifold. The passenger side one in the second pic gets a fitting and goes to the heater box I believe. The one on the drivers side I ahve no idea? maybe I can plug it. This next pic shows the port in the rear of the manifold. What goes in it? The fitting in the second pic? I think so, what goes to this fitting? I believe this is the sensor someone said to just get rid of all together. Is this correct? part of the TCS solenoid? THe line along the frame from rubber to steel, comes out of the bottom of the charcoal canister which will be removed from the truck. Where does that line go? can it be blocked? removed? left open? This comes off my heater assembly. what is the line with the screw? why is it plugged? What does this do? its unhooked, im sure I can pry it back properly. Any ideas? The line coming out of the brake booster, originally threaded into the rear of the carb, no provision I believe on the new carb. Where would it now go?

08-21-2009, 02:36 PM	#8
vegaschevy Account Suspended Join Date: May 2009 Location: las vegas nv Posts: 1,493	Re: Getting rid of smog equipment This line comes off the rear of the motor somewhere, where does it go? what does it do?

08-21-2009, 03:50 PM	#9
leddzepp Moderator Join Date: May 2007 Location: Southern Cal Posts: 19,996	Re: Getting rid of smog equipment Your third pic, from the bottom up, is the cowl vent control. This shuts off the outside airflow when the A/C is on. You need to run a vacuum line to this actuator. It shuts when the A/C is on, opens when the heater is on, A/C off. The pic above that is your heater shutoff valve. That needs to be closed when the A/C is on, prevents the heater core from heating up. Some had 2 vacuum nipples on them. Only one of them actually works. I would guess that the plugged line is connected to the nipple that doesn't work. You can probably just pull that line off. Your very first pic is the heat riser tube, not a filler tube. You can pull the tube, and the "stove" on the exhaust manifold and sell those. People looking to restore a truck to original are always looking for this setup. __________________ 1972 C/10 Cheyenne Super SWB. Restored, loaded, slammed. 1968 C/10 50th Anniversary LWB. Unrestored, stock, daily driver/work truck. RIP ElJay RIP 67ChevyRedneck RIP Grumpy Old Man Last edited by leddzepp; 08-21-2009 at 03:57 PM.

08-21-2009, 03:52 PM	#10
john member #16 Join Date: Dec 1999 Location: Yuba City Ca. Posts: 3,618	Re: Getting rid of smog equipment If there is no vacuum port on the carb you can use a fitting like this http://www.corvette-paragon.com/p-35...m-fitting.aspx and use a brake booster hose instead of the tube. The other small hose from your trans modulator (last pic) will plug on the small nipple. Heres a vacuum diagram for your a/c hoses. Attached Images __________________ john http://67-72chevytrucks.com/vboard/showgroups.php board vendors http://www.flickr.com/photos/1745471...7602865984234/ Last edited by john; 08-21-2009 at 03:55 PM.

08-21-2009, 05:36 PM	#17
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	Re: Getting rid of smog equipment The line off of rear of motor, transmission modulator, front drivers side plug it, can be used for heater hose, but use the pass side front, port in rear use for modulator valve, and you can hook up brake booster here also unless you want to use the one in the back of the carb base. And you can remove the pipe for the air cleaner too, tcs solenoid also, line by frame plug it, it goes up into cab near pass side next to fuel line. Heater valve I am unsure where the line goes, and the valve on firewall is for your a/c which I assume does not work anyway. I hope this helps!!!! __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

08-23-2009, 09:58 PM	#20
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	Re: Getting rid of smog equipment The Modulator valve is located on the passenger side of your transmission, if you have a Turbo 400 it will be on the side, if you have a Turbo 350 it is toward the rear of the passenger side. The Modulator valve controls shifting, you should be able to see the metal line coming from the rear of the motor down the side of the transmission. __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

08-23-2009, 10:03 PM	#21
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	Re: Getting rid of smog equipment Also if your carb does not have the provision for the brake booster then you can use the fitting in your hand in the pic, just hook it up to one side and your modulator valve line to the other. __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

09-03-2009, 11:22 AM	#23
vegaschevy Account Suspended Join Date: May 2009 Location: las vegas nv Posts: 1,493	Re: Getting rid of smog equipment I got everything else hooked up but still have not removed the transmission solenoid thing that hooks to vacuum. Also have not hooked up the vacuum line off the back of the motor that goes to the transmission. The tranny solenoid I can unplug, do theh wires need to be jumped or can i leave it unplugged? Also the vecuum line for the tranny can I just hook it to manifold pressure? the port on the passenger side rear of the motor?



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