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Unread 08-12-2009, 09:00 AM   #1
attworth
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1979 CJ7 
 
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Can somebody check my Vac. Diagram and answer some questions?

For starters, the motor is a 1979 258 I-6. The carb is a rebuilt Carter BBD, also 1979. The air intake box is also from a 1979.

I had some problems with my old exhaust manifold, and a nice guy locally gave me his from a 1985. I discussed mating it to my old intake, and the major problem was matching the ledges that the bolts clamp the manifolds onto the head. There was also the fact of the large gaping hole on the bottom of the old intake for heating the base of the intake path - which, although not a problem, was unsightly. I found a newer style intake, and went and picked it up last night.

I'm going through several vacuum diagrams attempting to make this work. I decided I should draw my own from scratch and try to alleviate some of my confusion. So far, it's helped a ton. I do have a few questions and was hoping somebody may be able to help me out.

I compiled the majority of knowledge from this site, http://home.sprynet.com/~dale02/list.htm, which was extremely helpful. I also used the Chilton's I have as a supplement, and for 1979 specific items.

Here is what I have so far.



The first thing that jumps out to me, is that I do not recall having the TAC system as shown. I don't have any good pictures of the intake box, and really can't remember. If the TAC is not present, is there something else I need to run the vacuum line from the Carb to the TAC to instead?

Next, is the Decel Valve. The website above clearly calls it a decel valve, as does the Chilton's for 80+ model 258's. The earlier model 258's have it called out as a Solenoid Vacuum Valve. As I'm not sure which is which, I ran the lines as it shows for the earlier model 258's under the assumption that it is a "Solenoid Vacuum Valve." I assume if this is the case, I can just take the old valve off my old intake, and replace the "Decel Valve" on the new intake.

In conjunction with the "Solenoid Vacuum Valve," there's the question of which "EGR" port on the Carb to use. The website linked above shows the EGR being ported from the back (firewall-side) of the carb. The Chiltons shows to use the forward (radiator-side,) and plug the back one. The website linked also does not seem to show two ports, but only the one.

Under the new intake is a round-ish plate with a wire coming out of it. I assume this works in conjunction with the temp sensor to heat the intake. I was under the impression that the water jacket in the intake manifold did that work, and the wires from the temp sensor told the computer when to start working. So what is this round-ish plate and wire for?

Finally, the vacuum canister seems wrong. There are 4 lines coming from the Vac canister. I only have 3 shown in my schematic. The only information I can find is that the 4th line goes to a "vacuum switch assembly," and specifically ties to the "idle/decel' port after being tapped to the carb. Note: the "Vac switch assy." and the "idle/decel" port are not the same as the "Decel Valve/Solenoid Vacuum Valve" discussed earlier.

I appreciate any help.



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Unread 08-12-2009, 11:00 AM   #2
attworth
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I'm going to throw another wrench into this equation.

Looking back through my diagrams, I'm a little more confused.

The diagram that I thought was applicable to a '79 model is listed at 71-74. There's no "complete" diagram for 75-79 in the Chilton's. The large diagrams that are shown are for 80-86 models, identical to the one posted on the website I linked in Post #1.

Here's the diagram for a 71-74 model. Major differences include a non-egr-integral exhaust back pressure sensor, and no TVS in the air intake. The other thing that's odd is the back (firewall-side) EGR port on the carb is blocked, and the line is shown to the front (radiator-side) EGR port.



Next is the diagram labelled "EGR system as on Inline 6 Engines." Notice the back-pressure sensor is integral to the EGR, and TVS is present. The line from the EGR CTO switch now goes to the rear (fire-wall side) EGR port on the carb, but does not continue to the "Decel Valve/Solenoid Vacuum Valve."



This next one is labelled "EGR system on 74-79 Inline 6 Engines." Notice the non-egr-integral exhaust back-pressure sensor, and no TVS. The EGR CTO switch port is also running to the rear (fire-wall side) EGR port on the carb, and does not continue to the "Decel Valve/Solenoid Vacuum Valve."



Finally, we have the "TCS system as used on Inline 6 Engines." This diagram shows the specifics of the Spark CTO Switch. Not much differs from what I was showing originally for the Spark CTO Switch. Notice the "Manifold source" is now going to an unknown manifold source (shown as a pentagon,) towards the front of the motor. Before reaching said source, a tee ties into the "Solenoid Vacuum Valve." It is not called a "Decel Valve," in this diagram. There appears to be the option of running a redundant vacuum line from the "Solenoid Vacuum Valve" to the original manifold vacuum source.



From what I understand, the TCS incoroprated a solenoid valve on the transmission body, which I do not have. I'm assuming this setup is not necessary.

So, I'm pretty confused at this point, but understand fairly well how all of this is supposed to work. I know for a fact I have the TVS on the Jeep (from the EGR.) I do not have the "3 port solenoids," or 10# and 4# switches with the pulse air system.

Again, any help is greatly appreciated.
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Unread 08-12-2009, 11:02 AM   #3
Mike Romain
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The TAC are the flaps on the snout and the controller is in the bottom of the air filter pan. If it is missing, there will be a hole in the air filter...

The EGR can feed off the front corner bottom nipple or the valve cover side center by sharing the distributor vacuum. Both those nipples are spark ported. Website isn't 100%...

The solenoid vacuum valve is a recalled part that used to control the PCV line. It gets tossed and a T fitting goes there only to pick up the canister purge line, the line below the valve on the canister. The little valve on the canister either gets a line from the valve cover side or the front corner for a ported signal via the CTO.

The one you are showing as a decel valve is a combiner that sends either ported or manifold vacuum to the distributor according to well deceleration for one I guess.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
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Unread 08-12-2009, 11:07 AM   #4
attworth
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Quote:
Originally Posted by Mike Romain View Post
The TAC are the flaps on the snout and the controller is in the bottom of the air filter pan. If it is missing, there will be a hole in the air filter...

The EGR can feed off the front corner bottom nipple or the valve cover side center by sharing the distributor vacuum. Both those nipples are spark ported. Website isn't 100%...

The solenoid vacuum valve is a recalled part that used to control the PCV line. It gets tossed and a T fitting goes there only to pick up the canister purge line, the line below the valve on the canister. The little valve on the canister either gets a line from the valve cover side or the front corner for a ported signal via the CTO.

The one you are showing as a decel valve is a combiner that sends either ported or manifold vacuum to the distributor according to well deceleration for one I guess.
Thanks for the input, Mr. Romain. I can't recall whether or not the TAC was part of this Jeep or not. As I understand it, the earlier models did not have it. I do not remember, however, any holes in the bottom of the intake.

"Solenoid Vacuum Valve" - That was my understanding as well, that it was a discontinued item between the PCV valve and the "Decel Valve." Chilton insists on calling the "Decel Valve" a "Solenoid Vacuum Valve." I think I just need to ignore that and know that it is as you said, a combiner that sends ported or manifold vacuum.
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Unread 08-12-2009, 11:11 AM   #5
Mike Romain
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Ouch, Ok.

bottom front corner, ported vacuum to feed to a CTO to feed an EGR via the TVS in the air filter side with a T at the CTO to feed the canister purge valve on top of the canister.

Valve cover side center, to distributor direct, most folks don't use the mixer or decel valve.

Center drivers side to the brake booster.

Back drivers side corner to the TAC system under the air filter.

Back passenger corner to the choke pull off.

Big center back one for canister and PCV line.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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Unread 08-12-2009, 11:29 AM   #6
attworth
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Quote:
Originally Posted by Mike Romain View Post
Ouch, Ok.

bottom front corner, ported vacuum to feed to a CTO to feed an EGR via the TVS in the air filter side with a T at the CTO to feed the canister purge valve on top of the canister.

Valve cover side center, to distributor direct, most folks don't use the mixer or decel valve.

Center drivers side to the brake booster.

Back drivers side corner to the TAC system under the air filter.

Back passenger corner to the choke pull off.

Big center back one for canister and PCV line.

Does this look correct? (No brake booster.)



Would this mean the distributor is always advanced under load? I guess the only problem would be increased "cold" emissions?

Still missing one port on the canister.
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Unread 08-12-2009, 11:34 AM   #7
attworth
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I think this might be what you meant. Sorry



Where do I pick up manifold vacuum?
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Unread 08-12-2009, 02:29 PM   #8
attworth
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Ok - here's a final.



Basically, I eliminate the Spark CTO along with the "Decel Valve," or diverter valve. My understanding is that this particular valve supplies fresh air to the system after removing load from the engine. In removing the Spark CTO, the distributor will always be allowed to use the vacuum advance curve. With the Spark CTO hooked up, it can only go into vacuum advance when the motor reaches operating temp (or very close to.)

For the very limited amount of time that the vehicle is not warm, I do not think removing the Spark CTO will have an ill affect. As long as we don't gun it first thing in the morning, which we never do, it should be ok. Does anybody else have an opinion on this matter? One thing that I might add is that the Jeep will have the JeepHammer "TeamRush" upgrade.

By removing the "Decel Valve," the system will not longer receive fresh air on deceleration. I assume the system recycles air and brings more in other ways - perhaps the vacuum canister helps with this? Is there anything bad that could happen by removing the decel valve?

I am also going under the assumption that we do not have the TAC system. I don't recall seeing it. If it is there, it will not be hard to route, as it is independent from all the other systems.

I am also curious if I need to pick up vacuum directly from the manifold. If so, where in line should it go?

I really appreciate any advice you guys/gals may have to offer. Keep in mind that I'm not trying to eliminate smog junk thinking we'll get more power, or lower emissions (or higher for that matter.) I'm simply trying to find a solution to this nest of extra stuff which isn't clearly laid out anywhere that I can find. Also, this is a rebuilt motor, so if you think something I'm intending to do may harm the motor, please let me know. I'd hate to void my warranty and lose a motor in the process.

Thank you again.
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Unread 08-13-2009, 06:13 AM   #9
attworth
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Quote:
Originally Posted by attworth View Post

Basically, I eliminate the Spark CTO along with the "Decel Valve," or diverter valve.

For the very limited amount of time that the vehicle is not warm, I do not think removing the Spark CTO will have an ill affect. Does anybody else have an opinion on this matter?

By removing the "Decel Valve," the system will not longer receive fresh air on deceleration. Is there anything bad that could happen by removing the decel valve?

I am also curious if I need to pick up vacuum directly from the manifold. If so, where in line should it go?

Thank you again.

Bump for the day. Thought about it some more last night. Still un-sure about the spark CTO and decel valve being issues.

I am pretty stumped about picking up manifold vacuum. I guess technically it isn't needed as everything is being sourced off of the carb, which is how the vacuum is created in the manifold in the first place. Correct?

Anyway, thanks again for any help.
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Unread 08-13-2009, 06:20 AM   #10
Mike Romain
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You will want the canister purge signal to T off the EGR line 'after' the CTO so both of them won't turn on until the coolant is warm.

You also only want a direct line from the float bowl top two big vent nipples to the canister, no tag to the manifold vacuum as shown in the top of your drawing. The manifold vacuum purge line goes direct to the PCV line T.

The distributor runs well on the direct ported vacuum, not really too sluggish when cold, it gives us 20+ mpg and I have tuned a mess of the feedback carb ones with no computer running them to still pass emissions.

The 'decel' valve is used with a cat and air tube system on the newer engines. Up here in Canada, only YJ's got them. That had me confused, had to go look it up: http://home.sprynet.com/~dale02/decel.htm

Do you have such a system with two big 1" tubes running from the exhaust catalytic converter to the air cleaner????

To see if you have a TAC, just look into the snout of the air filter. If you see a flap there and a bottom bypass hole you have a TAC system. It should then have a corrugated hose running down to a heat stove on the exhaust so it sucks hot air into the carb to prevent it from icing up in the cold. It is 'really' no fun to have a carb turn into a block of ice at 55 mph in a snowstorm.... If you don't run in the freezing weather, then no issues...

That should have you covered I think.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
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Unread 08-13-2009, 06:27 AM   #11
Mike Romain
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Quote:
Originally Posted by attworth View Post
Bump for the day. Thought about it some more last night. Still un-sure about the spark CTO and decel valve being issues.

I am pretty stumped about picking up manifold vacuum. I guess technically it isn't needed as everything is being sourced off of the carb, which is how the vacuum is created in the manifold in the first place. Correct?

Anyway, thanks again for any help.
Sometime thinking too much isn't a good thing..

No issues with spark ported vacuum direct for the advance, it will light up my 33's from a stop way too easy...

The manifold vacuum for the canister and PCV is a large hole in the rear of the carb base plate, the TAC manifold vacuum comes from the drivers side bottom back corner.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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Unread 08-13-2009, 06:40 AM   #12
attworth
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Hey Mike, thanks for the help.

I feel pretty dumb, but I do indeed have the TAC.



I'm not quite sure how to put the canister purge from the EGR after the CTO. It's a 2-port switch. I'll have the spare 3 port switch now since not using it for spark, but it is a different heat range.

We do not have a cat or the pulse tubes, so the decel valve will go.

In the picture below, there is a small "L" fitting in the manifold to supply vacuum to - something. I believe it originally went to "decel valve." Can I plug this now? Or does it need to be picked up elsewhere? (The EGR t'd off from the carb and ran to what this fed, the spark CTO tied into what this fed, and the PCV/purge was t'd off to what this fed [shown as "decel valve"])



I will remove the tie from the float bowl to manifold purge. The drawing for the canister had them tied together in the book - it's been wrong about a lot of things.

Thank you very much!
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Unread 08-13-2009, 07:20 AM   #13
Mike Romain
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Quote:
Originally Posted by attworth View Post
Hey Mike, thanks for the help.
You are welcome, oh your gas filter is in crooked, the return line nipple needs to be up top or gas will siphon back to the tank making for long cold starts.

Quote:
I'm not quite sure how to put the canister purge from the EGR after the CTO. It's a 2-port switch. I'll have the spare 3 port switch now since not using it for spark, but it is a different heat range.
The ported signal can come from that capped port on the front corner of the carb to the CTO. Then from the other side of the CTO the line goes to a T fitting with one side going to the canister and the other to the EGR TVS switch and on to the EGR.

Quote:
We do not have a cat or the pulse tubes, so the decel valve will go.
Good

Quote:
In the picture below, there is a small "L" fitting in the manifold to supply vacuum to - something.
For a different engine, plug and ignore.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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Unread 08-13-2009, 07:24 AM   #14
attworth
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Quote:
Originally Posted by Mike Romain View Post
You are welcome, oh your gas filter is in crooked, the return line nipple needs to be up top or gas will siphon back to the tank making for long cold starts.
Hrm... Makes sense! I'd like to relocate it somewhere 'safer,' but don't have the proper tools to do it right now.


Quote:
Originally Posted by Mike Romain View Post
The ported signal can come from that capped port on the front corner of the carb to the CTO. Then from the other side of the CTO the line goes to a T fitting with one side going to the canister and the other to the EGR TVS switch and on to the EGR.
Duh... Sorry. Didn't even think about that.


Quote:
Originally Posted by Mike Romain View Post
For a different engine, plug and ignore.
Good deal.

Thank you so much for your help Mike.

I owe you some
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Unread 08-13-2009, 12:29 PM   #15
Mike Romain
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Quote:
Originally Posted by attworth View Post
Hrm... Makes sense! I'd like to relocate it somewhere 'safer,' but don't have the proper tools to do it right now.
You have to have solid lines above the engine or insurance won't cover you in case of a fire as a friend that liked that braided crap found out the hard way.

The only exception is those three little gas line chunks that are supposed to get replaced every time the filter does, all the filters that I have bought all came with new clamps and hose chunks, so those are considered 'safe'.

Quote:
Thank you so much for your help Mike.

I owe you some
Well if you ever get up to the east coast of Canada, I'll take you up on those.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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