'77 FJ40 Federal 2F desmog

subzali

 
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Hey everyone,

I know there's great threads in the 60 series section on desmogging, but they mostly deal with FJ60s. I have a '77 Federal spec FJ40 and want some input if I'm going about this properly. So I've scanned some pages out of the Emissions FSM and used Paint to remove what I think needs to be removed.

First, here is the emissions diagram:


I think I want to remove the Air Pump (already done), EGR cooler (already done), EGR valve (already done), air by-pass valve (ABV) (already done), air rail (already done), and I think the vacuum switching valve (VSV) (for spark control (SC) system), the vacuum control valve (VCV) No. 2, VCV No. 1, the bimetal vacuum switching valve (BVSV), and the vacuum transmitting valve (VTV). The VSV for SC and VCV No. 2 I'm not sure about. I think I want to keep the throttle positioning (TP) system and the VSV for TP & EVAP. This is all from reading the emissions manual, so if I'm wrong and I'm keeping systems I don't need or I'm getting rid of systems I want please let me know.

Anyway here's what I come up with schematically by removing these components:


Here's an isometric view of the whole emissions system:


Here's what I think I need to delete:


And here's what I think it will look like when I'm done (also notice that I have a fully electronic ignition with the later style distributor. This means that the cap is vented. I have a line running to the glovebox with a filter attached, and the other end running to the air cleaner. I have heard that running it directly to the air cleaner can cause a distributor explosion if fuel vapors reach their way into the dizzy. So does anybody have any suggestions on how to run this so that doesn't happen? On FJ60s the line is run to a VCV I think; do I need to tie-in to my VCV No. 1 somehow to make that happen?):


Any suggestions or recommendations? What's the deal with rebuilding the carburetor and distributor for non-smog service? I don't understand why, especially, the distributor needs to be re-curved, or what that even means.

Thanks
 
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I THINK that in 77 the dizzy was a vacuum retard...you prolly want to get a vacuum advance dizzy and I THINK you'll need to pull a vacuum line from the old egr cut port to the advance can of the advance dizzy. There is a vcv that controls the dizzy venting in the later model 2fs and is operated by manifold vacuum from your 2 port vacuum filter on the front side of the manifold. If the carb work, you can prolly run it fine. The dizzy recurve is because there is too much total advance in the 60 series dizzy when full vacuum advance is combined with full mechanical advance while NOT running egr. HTH a bit. I'm sure someone will come along and dial you in.....
 

subzali

 
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According to this web page in the tech links, Jim C. says that a stock '77 dissy should be a points-type dissy with vacuum advance (thanks to Jim C. later in this thread pointing this out to me). Mine is actually a '79-'80 fully electronic dissy with dual vacuum advance. Currently my inner diaphragm is connected to vacuum and my outer diaphragm is capped off.
 
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Great thread. I have an 8-77 2f that's been desmogged and this really helps. I have been wondering what that blue bvsv was for. Mine is not capped. What does it do and why are you saving it?
 
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You can loose VTV and VSV lines by running the charcoal canister direct to the tank and loose the emissions computer if you run a wire from a switched fuse to the idle solenoid. Everything else in the computer can be turned off.
 

dgangle

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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.
 

Pin_Head

 
 
 
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What's the deal with rebuilding the carburetor and distributor for non-smog service? I don't understand why, especially, the distributor needs to be re-curved, or what that even means.

Thanks
It is not an issue of rebuilding. The carb and distributor on most smogged models were designed to be operated electronically and they are not set up to function properly without the external control. For example, some years lack the appropriate vacuum ports on the carb for strictly mechanical control. Some distributors are vacuum retard, while others do not have the range of advance optimal for mechanical operation.

What I think you are missing is that this electronic engine control is not just for smog reduction but it is also there to make the engine operate more efficiently under more different conditions and meet CAFE standards. It isn't all bad, so just removing it isn't all good.
 

subzali

 
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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 had to get my emissions tested when I bought my 40 in 2005. I got Collector's Plates at that time, so as long as I don't forget to renew my registration, and as long as I don't sell it (or don't sell it to someone in an emissions area) then I never need emissions again. The grandfathering laws haven't affected that. If I were to forget my registration then you're right; I would probably never be able to go more than 2 years without an emissions test ever again without moving to an emissions-exempt area. I'm keeping all my smog components in a box just in case though, and it's easy enough to put back together.

It is not an issue of rebuilding. The carb and distributor on most smogged models were designed to be operated electronically and they are not set up to function properly without the external control. For example, some years lack the appropriate vacuum ports on the carb for strictly mechanical control. Some distributors are vacuum retard, while others do not have the range of advance optimal for mechanical operation.

What I think you are missing is that this electronic engine control is not just for smog reduction but it is also there to make the engine operate more efficiently under more different conditions and meet CAFE standards. It isn't all bad, so just removing it isn't all good.
So why is desmogging a big hit with the 60 series folks? Are there more gains to be realized with them than with the FJ40 emissions equipment, so it's not worth the trouble to remove the FJ40 emissions equipment? Even still, it seems to me that there are some systems that reduce the efficiency of the engine (EGR/air pump for example). So what I've tried to understand by reading the manual is what systems are beneficial to the engine's operation and which are purely for emissions, and essentially de-tune the engine in order to make the emissions better. Am I on the wrong track?
 

Pin_Head

 
 
 
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So why is desmogging a big hit with the 60 series folks? ?
I don't understand this popularity either. There is lack of understanding of what the electronic engine control systems do and there is a herd mentality and people are hungry for any way to get a little bit better performance and economy.

The EGR system leads to a small inefficiency by lowering combustion temperature (The TdeltaS side of the Gibbs free energy equation), but this effect is also exploited to allow a leaner mixture to be burned at high speed cruising so the overall effect is positive. If you disable the EGR, you would want a richer mixture to keep the combustion temperature within a safe range.

The air pump takes a little power to turn it, but this is very small compared to the power required to move the vehicle. I would guess it is less than 1%.

Any time people spend significant money or time on anything, there is a strong bias to believe that the effort has been beneficial. This is known as observer bias
 

numby

 
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I think I want to keep the throttle positioning (TP) system, the VSV for TP & EVAP, VCV No. 1, the bimetal vacuum switching valve (BVSV), and the vacuum transmitting valve (VTV).
Keeping the TP system will really cut down on afterfire (backfiring) on deceleration. You'll lose a little compression braking at the speeds at which the TP system works. I think it's somewhere between 25 mph and 8 mph. Check the manual.

The BVSV is a temperature controlled switch. Keeping the BVSV allows a system to operate at the correct operating temp. That's generally a good thing. Yours seems to only affect the EGR system (which you're removing) and the operating parameters for the 77's vacuum retard distributor. If you actually have a fully electronic ignition (78+) instead of the original 77 semi-electronic then you can't really make use of any part of the system. Time for an HEI if you've got a advance port on the carb. I' don't think you do.

The VTV sort of parcels out the vacuum or slows its bleed-off. Not needed unless you're keeping the whole dizzy she-bang including the comp and VSV.

...also notice that I have a fully electronic ignition with the later style distributor. This means that the cap is vented. I have a line running to the glovebox with a filter attached, and the other end running to the air cleaner. I have heard that running it directly to the air cleaner can cause a distributor explosion if fuel vapors reach their way into the dizzy. So does anybody have any suggestions on how to run this so that doesn't happen?
This is fairly silly. The line that rums to the ac is supplying vacuum so the airflow is almost always toward the engine. .. although the way it works on my 78 is that there is a small metal debris filter at the AC connection point. Spark arrester? I doubt it.:rolleyes:

Any suggestions or recommendations? What's the deal with rebuilding the carburetor and distributor for non-smog service? I don't understand why, especially, the distributor needs to be re-curved, or what that even means.
Well, if you're getting rid of the factory controls you need to accomplish the timing needs via other means both mechanical and vacuum. Remember - timing is not static. The engine doesn't run at the 7 deg (or whatever) you set it at during the last tune up.
 

numby

 
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... and I THINK you'll need to pull a vacuum line from the old egr cut port to the advance can of the advance dizzy. There is a vcv that controls the dizzy venting in the later model 2fs and is operated by manifold vacuum from your 2 port vacuum filter on the front side of the manifold.
Is the EGR cut port manifold or ported vacuum?

The egr port probably supplies vacuum too late to do any good for distributor advance but you'd have to ask Jim C.
 
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I don't understand this popularity either. There is lack of understanding of what the electronic engine control systems do and there is a herd mentality and people are hungry for any way to get a little bit better performance and economy.

The EGR system leads to a small inefficiency by lowering combustion temperature (The TdeltaS side of the Gibbs free energy equation), but this effect is also exploited to allow a leaner mixture to be burned at high speed cruising so the overall effect is positive. If you disable the EGR, you would want a richer mixture to keep the combustion temperature within a safe range.

The air pump takes a little power to turn it, but this is very small compared to the power required to move the vehicle. I would guess it is less than 1%.

Any time people spend significant money or time on anything, there is a strong bias to believe that the effort has been beneficial. This is known as observer bias
Amen. I always think this when I read desmog threads, but I've never bothered to type it all out. Thanks! :beer:
 

numby

 
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Try getting parts for old smog equipment when it fails. Not easy - even on mud.
 

subzali

 
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Okay, so let's take a different tack with this thread. The PO put on a fully electronic ignition system; it's a '79 to '80 small cap distributor. Here's a picture of the distributor, notice how I have the outer vacuum advance port plugged:


And here's a picture of that side of the engine bay (you can see the hose up to the air cleaner and the hose to the firewall to vent the cap:


What I'm also finding out is that I have a 9/77-12/78 Federal spec carb, even though my 40 is a 10/76.

So are the '79-'80 distributors and '78 carburetors compatible with the other emissions equipment from a '77? Let's assume I keep all the emissions equipment for my '77, do I need to do anything different with my vacuum connections? This carb has the EGR Port, EGR Cut Port, and TP Diaphragm, which should be the same as what was stock. But it also has an HIC valve (shown), which Jim C. has so kindly pointed out later in this thread connects to the side of the carb insulator base:


I was also wondering as I was looking at the emissions manual, what are the differences between the different colors of VTVs (red and blue), BVSVs (blue and brown)?

Anyway, any help would be appreciated.
 
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I don't understand this popularity either. There is lack of understanding of what the electronic engine control systems do and there is a herd mentality and people are hungry for any way to get a little bit better performance and economy.
...
Amen. So many things are done to cruisers just because someone else did it. Learning what these systems do and keeping them in working order (things apparently beyond the reach of most cruiser DIYers) gives you a nice running and not too smelly ride.
 

numby

 
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What I'm also finding out is that I have a 9/77-12/78 Federal spec carb, even though my 40 is a 10/76.

So are the '78 distributors and '78 carburetors compatible with the other emissions equipment from a '77?
Not completely I would think. The TP and the Evap system certainly would be. The 77 EGR system probably has some factors that require the 77 emission computer and related vacuum hose routing. The distributor functioning is pretty different.

Let's assume I keep all the emissions equipment for my '77, do I need to do anything different with my vacuum connections? This carb has the EGR Port, EGR Cut Port, and TP Diaphragm, which should be the same as what was stock. But it also has what is (I think) a fuel bowl vent, where is that supposed to go? Here's a pic, is this hooked up to the right place?:
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 recurved and you would only need a line from the advance port on the 78 carb to the vac. adv. can on the 78 distributor.

No that's not a fuel bowl vent. I don't remember what Jim C. called it but it has a little flapper valve in there that opens and closes with vacuum. I didn't know that it connects in the way your is - i.e. - to the vacuum surge tank which is a 77 specific smog component and not found on a 78.

I was also wondering as I was looking at the emissions manual, what are the differences between the different colors of VTVs (red and blue), BVSVs (blue and brown)?
The different VTVs seem to bleed off or allow the build up of vacuum at different rates. The different BSBVs open at different operating temps to control when various vacuum-actuated smog stuff comes into play.

You need a 77 and a 78 emission manual to compare how all the above systems work. They will tell you when each system is operational by temp, etc.
 
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