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1978 B210 vacuum hose routing


ggzilla

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would be interested in some more info on the topic of vacuum lines.

 

I also have a '78, auto with CAL emissions

 

The carb only has four vaccum hoses. All the other hundreds of hoses are for the air pump & other stuff

 

1. Vacuum advance port

2. Choke Pull-off port & diaphragm

3. EGR port

4. Throttle Opener diaphragm is attached to the carburetor and uses manifold vacuum. It has no carburetor vacuum connection.

 

Here's a diagram I colored in:

DCH306_hoses.jpg

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That's not the CAL diagram, but since you've already removed EGR and smog pump, it's probably best to start from scratch. Is simple to connect the other systems, the EGR and smog pump are the most complex.

 

1. VACUUM ADVANCE. Connect a hose from the distributor to the port connection directly above the idle mixture screw.

2214.jpg

 

Also Tee into this line and connect a hose to the Charcoal Canister "VC" line. The canister is for the Fuel Tank vent. Since B210 tanks are sealed, it needs to vent somewhere.

 

That takes care of the green and pink lines in the diagram. My understanding is that CAL didn't have a spark delay valve.

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VACUUM ADVANCE. You want this as more advance = more power. This is a good system that adds extra performance, better fuel economy, and smoothness to the driving experience. And because vacuum is zero at full throttle, it has no effect on full throttle performance.

 

Just check to make sure it holds vacuum. Most are leaking. If yours is leaking, just plug the hose. It'll run better plugged than leaking. But you won't get good fuel economy, so best to replace it. Sometimes you can find them at wrecking yards still working. Or buy a new one for $75. Units from many other Datsuns fit, and some Honda and Subaru.

 

14074.jpg

 

 

You can also test it without a vacuum gun. Move it with screwdrive and check to see if will hold under your thumb.

 

2216.jpg

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CARBON CANISTER runs off the Vacuum Advance connector on the carburetor, teed into the same hose.

 

16807.jpg

 

just three connections:

1. Fuel tank vent line (connection by itself)

2. PURGE - to intake manifold (bottom connector)

3. Vacuum Control (top connector) - to vacuum advance hose

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Cool, well everything covered so far I have hooked up. My car had no egr originally so scratch that. Funny that cali cars had no egr. Nothing under my air cleaner is hooked up.

 

I do have the thermactor control valve in the head and I need the warm air to work if possible. Is there any reason for the altitude valves?

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2. Choke Pull-off port, hose & diaphragm. Nissan calls this the "Vacuum Break"

 

This long black hose goes to the choke pull-off diaphragm (vacuum motor):

23417.jpg

 

2211.jpg

 

Test this diaphragm the same way as the vacuum advance.

 

22832.jpg

 

Hopefully it won't be leaking.

Again, better to plug this than have it leaking. You can drive the car with this plugged, but after a cold start it will run very rich for some time until the choke warms up a bit. It may even want to die unless you have your foot on the pedal a bit.

 

Only about $15 for a new one if you compare prices.

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CAL engines came with EGR in 1978, all did CAL, FED, CAN. Maybe the PO put an older manifold on or something.

 

 

Is there any reason for the altitude valves?

 

Only for high altitude driving (over 4000 ft). Say if you go to Tahoe, it will run a bit rich w/o the altitude compensator. If you go to higher you can even notice it. The compensator takes care of that (assuming it still works after 35 years)

 

Altitude Compensator - 2 connectors near top of carburetor

23417.jpg

 

 

For testing at low altitudes, remove the hoses and plug the ports coming out of the casting. The carburetor will run as normal. Most B210s didn't have this, but only those sold in california and in non-CAL high-altitude counties.

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EGR

 

3rd connector on carburetor is for EGR, if this is missing from your B210, on the carburetor, plug the port connection that is slightly above the Vacuum advance port (and above the idle mixture screw on the rocker cover side of the carb).

 

For testing, you can drive the car under all conditions with the EGR port plugged. Performance should be equal or better with it plugged.

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4th and last (unless yours has altitude compensator) is the Throttle Opener diaphragm which is attached to the carburetor. Was used on all 1978 B210s except the FU engines (5-speed models).

 

orange hoses in the diagram above: a single vacuum hose from the intake manifold to the switch. Then another from the switch to the Throttle Opener. In the diagram it shows a 3rd hose on the switch, which goes to the bottom of the air filter. That's all the hoses it uses. The rest is electrics.

 

If operating correctly, the throttle opener does not interfere with driving, although it does hold the throttle open a little during shifting. If misadjusted, it will be intrusive, holding the throttle open too far or for far too long.

 

Quick Test: Remove the hose at the intake manifold and plug it. See if the engine runs better. The car will drive OK with this plugged -- I think. Let me know how it works.

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I need the warm air to work if possible

 

Yep, you won't get top fuel mileage if the warm-air intake doesn't work. Because the carbs are jetted lean for a specific temperature. And you lose no performance. Because it runs off vacuum, when you floor it vacuum is zero, and the warm-air intake shuts thus drawing only cold air intake. The power valve compensates for the denser air at full throttle, so you get maximum power.

 

Nissan "Automatic Temperature-Control Air Cleaner" (A.T.C. Air Cleaner)

 

Half the ones I work on are leaking. Check it a vacuum gun or use the finger method. You can reach up and push the flap open and see if it holds under your thumb. Plug if it is leaking.

 

Let me see if I can find a diagram.

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I'll post up some pics tomorrow with what mine looks like. The diagram I had from Mitchell vintage was specific to '78 cali with an auto and it showed no provision for EGR. There are no fittings in my intake or exh either. Sure its possible the mani's may have been swapped but I know the previous owner and he had the car since early '80's.

 

Either way I'm not worried about EGR that much. I need a new Dizzy, my vacuum advance is shot and it won't come out of the housing so its going to take a new unit. And going into winter here I need to hook up the warm air flap in the air cleaner. It did ok this morning at 17* F but I like to have all the proper things working if possible.

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Nissan "Automatic Temperature-Control Air Cleaner" (A.T.C. Air Cleaner)

 

The factory service manual doesn't have a good diagram showing the hose clearly except the visible one.

 

Vacuum Motor & exhaust manifold Duct Tube

23093.jpg

 

For 1978 B210 CAL, same as all the other years and FED/CAN/CAL all the same.

 

1. Hose from intake manifold to the underside of the air cleaner

 

2. ATC temperature sensor, inside the air filter, is a large round or square thing. It has two hose connectors on the bottom side.

 

3. Hose from bottom of the air cleaner to the Heat Control Valve (vacuum motor diaphragm).

 

16775.jpg

 

16776.jpg

 

The hose can go to any port on the intake manifold.

 

Older models had it connected to the tap behind B in this photo...

22830.jpg

... But you could connect it to D or C, as long as it is an intake manifold connection.

 

At idle:

* Below 38F underhood temp, the hot air flap should be open (drawing hot air)

* Above 131F underhood, hot air flap should be closed (drawing 'cold' air)

* Between these temps, partially open. A slight hiss/buzz should be audible if the air cleaner lid is off.

 

If the vacuum motor is leaking, you could plug the hose. For winter you can jury-rig the air flap half way open. Early japan models had a manual winter/summer lever, so it would work to leave it at one position at least for anti-icing protection.

 

14992.jpg

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<br />I'll post up some pics tomorrow with what mine looks like. The diagram I had from Mitchell vintage was specific to '78 cali with an auto and it showed no provision for EGR. There are no fittings in my intake or exh either. Sure its possible the mani's may have been swapped but I know the previous owner and he had the car since early '80's. <br /><br />Either way I'm not worried about EGR that much. I need a new Dizzy, my vacuum advance is shot and it won't come out of the housing so its going to take a new unit. And going into winter here I need to hook up the warm air flap in the air cleaner. It did ok this morning at 17* F but I like to have all the proper things working if possible.<br />
<br /><br /><br />

 

 

it should have had one. my automatic '76 from cali did

 

 

this should be stickied here

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The 1978 Factory Service Manual is like 400 pages thick. It has tons of diagrams and schematics for every little system.

 

Here's the overview drawing:

B210_1978_CAL_EC.jpg

 

and here's the simplified hose diagram from the Tune-up section:

B210_1978_CAL_TU.jpg

 

There are four different models as far as fuel/emission specs go:

* FED (U)

* CAN (N)

* CAL (V)

* MPG/FU (F)

 

So CAL FU is different from CAL. All have two variations: MT and AT (except FU which by definition is 5-speed). It gets confusing.

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  • 1 month later...

Zilla this thread is killa. As always thanks for the help I'm going to track down any vacuum leaks etc and see if that fixes the issues. I imagine it will because previous owner just ripped all emmissions stuff off and zip tied the choke open to get it to run. This is perfect to troubleshoot my carb issues. I'm missing all the hoses and diaphragms and the air cleaner. That's is probably why it runs like crap and won't idle.

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  • 2 years later...
  • 1 month later...

2. Choke Pull-off port, hose & diaphragm. Nissan calls this the "Vacuum Break"

 

This long black hose goes to the choke pull-off diaphragm (vacuum motor):

23417.jpg

 

2211.jpg

 

Test this diaphragm the same way as the vacuum advance.

 

22832.jpg

 

Hopefully it won't be leaking.

Again, better to plug this than have it leaking. You can drive the car with this plugged, but after a cold start it will run very rich for some time until the choke warms up a bit. It may even want to die unless you have your foot on the pedal a bit.

 

Only about $15 for a new one if you compare prices.

This is another great thread thanks for all this info.

 

Is there any reason why my NEW mechanic would run the line from the choke pull off diaphragm down below the carb?

And leave the other end open?

 

Wondering if he got mixed up. The car was having the usual idle troubles. I got it from his shop yesterday ran, decent but then began stalling out again.

Any help would be super appreciated. thank you

 

Here's a picDZ9U2oC.jpg

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