Vacuum Line at Carb Question

[fjc-man]

Alright search “21335-61021 thermostatic valve” Pinhead came up with the best automotive description of what the likely function of this unit does on a hot, idling engine. Check it out, this is from about a year and a half ago.

 

[PabloCruise]

What does that 7H30 date code on your carb translate to, or is that how you determined it is 78 model year? I think your doohickey is the same as a 79 except yours is drawing filtered air from that port rather than from the air cleaner.

My understanding of the date code:
7 = Year of Manufacture - 1977
H = Month of Manufacture - August
30 = Day of Manufacture - 30th

So it is a late (very late) Aug, '77 carb.
Maybe it is a '77 carb? IDK.

I am hoping @FJ40Jim has time to weigh in and elaborate.

The rest of my 40 looks like MY '78 emissions equipment. IIRC, @subzali has pretty good thread about desmogging his '77 40. I might go check there and see if he has good pictures of his carb.

I appreciate your replies, but I do not think the thermal device you have on your '79 is on my carb.

 

[mattressking]

This is my assumption, more of a datapoint and without a '78 emissions manual in my hand to hunt through, is my best guess.

The bottom HIC port would go to a manifold vac source that I believe @65swb45 was mentioning. See the '78 insulator here, it would be the left port. Right port would go to the VCV for EVAP.

@Andrew S posted a good photo of the routing...which I'm still not positive is correct, but after hunting and looking at a few original '78s, it seems like it is. See second image confirming as well.

 

[Pin_Head]

I appreciate your replies, but I do not think the thermal device you have on your '79 is on my carb.

There is a very similar one on '78 carbs; it is just facing to the front and not to the side. Both contain the hot idle compensator thermo switch and connection tubes for some of the VSVs.

 

[PabloCruise]

This is my assumption, more of a datapoint and without a '78 emissions manual in my hand to hunt through, is my best guess.

The bottom HIC port would go to a manifold vac source that I believe @65swb45 was mentioning. See the '78 insulator here, it would be the left port. Right port would go to the VCV for EVAP.

View attachment 3547717

@Andrew S posted a good photo of the routing...which I'm still not positive is correct, but after hunting and looking at a few original '78s, it seems like it is. See second image confirming as well.

View attachment 3547718
View attachment 3547730

Thanks for your help.
I am going to connect it to the forward port on the insulator for manifold vacuum.

 

[PabloCruise]

There is a very similar one on '78 carbs; it is just facing to the front and not to the side. Both contain the hot idle compensator thermo switch and connection tubes for some of the VSVs.

Thanks!
Where the heck does Toyota describe these functions? In the Carb Manual?
Not in the Engine or Emissions Manuals...

 

[PabloCruise]

My understanding of the date code:
7 = Year of Manufacture - 1977
H = Month of Manufacture - August
30 = Day of Manufacture - 30th

So it is a late (very late) Aug, '77 carb.
Maybe it is a '77 carb? IDK.

I am hoping @FJ40Jim has time to weigh in and elaborate.

The rest of my 40 looks like MY '78 emissions equipment. IIRC, @subzali has pretty good thread about desmogging his '77 40. I might go check there and see if he has good pictures of his carb.

I appreciate your replies, but I do not think the thermal device you have on your '79 is on my carb.

I went and found the @subzali thread, and sure enough there are some Jim C knowledge in there.

The metal box is the HIC, aka Hot Idle Compensation. It should connect as we have deduced earlier:

'77 FJ40 Federal 2F desmog

...The distributor functioning is pretty different...78 carbs have an EGR port, an advance port and a TP port. I don't know what an EGR cut port would do. A 78 distributor requires the 78 computer to function to factory specs. That doesn't mean you can't run it but the distributor should be...

forum.ih8mud.com

and:

'77 FJ40 Federal 2F desmog

...The distributor functioning is pretty different...78 carbs have an EGR port, an advance port and a TP port. I don't know what an EGR cut port would do. A 78 distributor requires the 78 computer to function to factory specs. That doesn't mean you can't run it but the distributor should be...

forum.ih8mud.com

and

'77 FJ40 Federal 2F desmog

Not IF but WHEN emission checking is started in your area, you will wish you never did this. Grandfathering in most, if not all states, only goes back to '75 on 40's. I don't understand this popularity either. There is lack of understanding of what the electronic engine control systems do and...

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Purpose of HIC, according to Jim C: The HIC will leak additional air into the manifold fitting when hot, to raise & stabilize the idle.

'77 FJ40 Federal 2F desmog

...The distributor functioning is pretty different...78 carbs have an EGR port, an advance port and a TP port. I don't know what an EGR cut port would do. A 78 distributor requires the 78 computer to function to factory specs. That doesn't mean you can't run it but the distributor should be...

forum.ih8mud.com

I guess the connection on the top/front of my carb in question is not to the Power Valve? Jim says they were internally connected in '78:

'77 FJ40 Federal 2F desmog

...The distributor functioning is pretty different...78 carbs have an EGR port, an advance port and a TP port. I don't know what an EGR cut port would do. A 78 distributor requires the 78 computer to function to factory specs. That doesn't mean you can't run it but the distributor should be...

forum.ih8mud.com

 

[PabloCruise]

Looks like this was a question back in '08 - that's a minute ago!

VSV part for 78 FJ40

Thanks much for the diagrams - I'm still trying to locate 78 manuals. So was there a carb in 78 without the HIC (doesn't Spector show the 2 - earlier post)? And - could this mean my carb is not original to the vehicle? This is one of the best sources for Toyota Manuals. It is where I...

forum.ih8mud.com

 

[PabloCruise]

I have a 79 emissions manual and there is no mention of this doohickey. It appears to be a controlled vacuum leak at higher temperatures, I warmed it up with a heat gun and that’s when it opened to the air cleaner. There is a bimetallic spring acting on that plunger.View attachment 3546816View attachment 3546817

Thanks for chiming in! Here someone pulled the cover off the HIC for a '78 - look familiar?

VSV part for 78 FJ40

Thanks much for the diagrams - I'm still trying to locate 78 manuals. So was there a carb in 78 without the HIC (doesn't Spector show the 2 - earlier post)? And - could this mean my carb is not original to the vehicle? This is one of the best sources for Toyota Manuals. It is where I...

forum.ih8mud.com

 

[PabloCruise]

Thanks!
Where the heck does Toyota describe these functions? In the Carb Manual?
Not in the Engine or Emissions Manuals...

I am still hoping someone w/ a Carb Manual will weigh in on this!

 

[PabloCruise]

Jim C weighs in on '78 Fed Spec desomg here:

Help with 1/2 way done Desmog!!

Just purchased a project that was 1/2 completed. Previous owner attempted a desmog and got 1/2 way through it. Not sure where to begin. Does anyone have a diagram/schematic/map of a desmog? This is a 2F, don't know where to start since i am just inheriting someone else's work. (I did get a...

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[PabloCruise]

In this thread, @Fbks_cruiser took the above schematic and applied it to the layout diagram from the Emissions Manual for '78 Fed spec:

layout for 78 2F desmog

After some thought and a fair amount of consultation with Jim C. I came up with these diagrams for a desmogged 1978 2F. I shamelessly scanned the FSM diagrams and did a bit of editing. Jim Suggested that I post them here so others could benefit and perhaps save some questions. I think it...

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EDIT - If I am looking at this correctly, this completely eliminates the VSV!

 

[PabloCruise]

In the same thread, @FJ40Jim shares that the 80 series VCV can be substituted for 40/55/60 series:

layout for 78 2F desmog

Jim Which BVSV can I plug with the kit I purchased from you? I seem to have 2 plugs I’m confused where to put them? I also purchased desmogged carb for this. Thanks See post #1 for drawing showing which BVSV remains connected to vacuum.

forum.ih8mud.com

Toyota P/N 90925-03192 City Racer carries them: OEM Vacuum Control Valve / VCV for Land Cruiser FJ40 FJ60 FZJ80 - https://www.cityracerllc.com/products/oem-vacuum-control-valve-vcv-for-land-cruiser-fj40-fj60-fzj80 as well as a notice that 2 of the ports are reversed from earlier: Note that for FJ40 and FJ60 applications, the orientation of the two horizontal ports on the bottom (in black) are reversed from the old VCV. Thus, prior to replacement, take note of which hose goes to the larger port vs. the smaller one.

This thread details exactly how I broke my VCV, as well as a reminder that the 80 series ports on the VCV are reversed: VCV replacement - https://forum.ih8mud.com/threads/vcv-replacement.1252977/

Just note that the two ports on the black section of the new VCV are reversed from the older white version.

 

[PabloCruise]

City Racer also carries the blue and brown BVSVs:

OEM Blue BVSV for Land Cruiser FJ40 Pick-up 4Runner

Blue BVSV / Bimetal Vacuum Switching Valve for: '76 to '80 Land Cruiser FJ40, BJ40, FJ45, FJ55 '80 to '86 Toyota pick-up '84 to '86 4Runner OEM part # 90925-05017.

www.cityracerllc.com

Brown BVSV for Land Cruiser FJ40 FJ55 FJ75

Brown BVSV / Bimetal Vacuum Switching Valve for: 9/'77 to 1/'79 Land Cruiser FJ40, FJ55 6/'90 to 8/'92 Land Cruiser FJ75 Reproduction of OEM part # 90925-05041. Discontinued by Toyota. Needed for passing smog.

www.cityracerllc.com

 

[PabloCruise]

City Racer also carries the blue and brown BVSVs:

OEM Blue BVSV for Land Cruiser FJ40 Pick-up 4Runner

Blue BVSV / Bimetal Vacuum Switching Valve for: '76 to '80 Land Cruiser FJ40, BJ40, FJ45, FJ55 '80 to '86 Toyota pick-up '84 to '86 4Runner OEM part # 90925-05017.

www.cityracerllc.com

Brown BVSV for Land Cruiser FJ40 FJ55 FJ75

Brown BVSV / Bimetal Vacuum Switching Valve for: 9/'77 to 1/'79 Land Cruiser FJ40, FJ55 6/'90 to 8/'92 Land Cruiser FJ75 Reproduction of OEM part # 90925-05041. Discontinued by Toyota. Needed for passing smog.

www.cityracerllc.com

I found this info on operating temps of the various BVSV colors:

BVSV COMPATIBILITY 60's to 40's

Broke the knobs off my darn BVSV when I was putting it back in my lower thermostat housing after a thermostat change!! CRAP!! It's the green one the screws into the top port. I don't have a direct replacement but I do have 2 that came off of my 85' FJ60. A purple one and a reddish one...

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It looks like both blue and brown open at 129 F. So why the different colors? Maybe to make it easy to tell what system you are working on? They do not open at the same temps, I will post up details soon.

Another post w/ info on BVSV temp vs colors:

Two Vacuum Switches on Thermostat Housing???

forum.ih8mud.com

 

[Fast Eddy]

I have a 79 emissions manual and there is no mention of this doohickey. It appears to be a controlled vacuum leak at higher temperatures, I warmed it up with a heat gun and that’s when it opened to the air cleaner. There is a bimetallic spring acting on that plunger.View attachment 3546816View attachment 3546817

Edit: Ah. Late to the party. "Thermostatic Valve" seems to be it. Still not mentioned by name.

That little guy shows up in the emissions manual, but I don't see where it's ever given a name and it doesn't have it's own test procedure like all the other components. 2 ports for CA, TP and EGR run from the carb base ports through this. For federal there's one more port for the spark arrestor which goes to the advancer port at the carb base.

 

[65swb45]

Edit: Ah. Late to the party. "Thermostatic Valve" seems to be it. Still not mentioned by name.

That little guy shows up in the emissions manual, but I don't see where it's ever given a name and it doesn't have it's own test procedure like all the other components. 2 ports for CA, TP and EGR run from the carb base ports through this. For federal there's one more port for the spark arrestor which goes to the advancer port at the carb base.

Thanks for chiming in Ed. I have no idea where my manuals are right now. I haven’t seen them since the warehouse fire when I moved my office, and I don’t feel like spitballing.

Any chance you can scan those?

I will add though that my memory was correct about the little red hose with the 180. I had to move something on my carburetor workbench yesterday and I found one of those thermostatic boxes leftover from a desmog. It still had the U shaped red hose that went up to the top of the carb.

 

[Fast Eddy]

Any chance you can scan those?

If anyone needs a diagram or reference let me know, but I'm swamped at work and can't do a full scan at the moment. I have a 1978 2f emission control repair manual (pub #98270) that I got from SOR way back when.

 

[1911]

Attached is a PDF of the 1981 2F Emission Control Repair Manual, if it's of use to anyone.

 

[PabloCruise]

Edit: Ah. Late to the party. "Thermostatic Valve" seems to be it. Still not mentioned by name.

That little guy shows up in the emissions manual, but I don't see where it's ever given a name and it doesn't have it's own test procedure like all the other components. 2 ports for CA, TP and EGR run from the carb base ports through this. For federal there's one more port for the spark arrestor which goes to the advancer port at the carb base.

We are getting some great responses in here!
I have not seen it show up in my manual, so I would love to see hear more about it, as the vacuum port that started this thread is affected by it! The EGR, TP and Advancer lines just look to pass through.
I saw here where you referred to it as the HIC - Hot Idle Compensator: VSV part for 78 FJ40 - https://forum.ih8mud.com/threads/vsv-part-for-78-fj40.226005/page-2#post-3451725