Weber carburetor questions

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Mogordo
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My tercel:: 1983 SR5 Wagon

Weber carburetor questions

Post by Mogordo »

I got to looking over Weber vacuum posts and looking at how my car is set-up (how it came when I got it) and I'm having trouble figuring it out. I think I may end up disconnecting all on there and just connecting what dlb suggests in his FAQ guide but even there I got stuck figuring how that would go. I don't know carburetor/fuel systems well in general and two things I specifically got stuck on are what the purge port on the charcoal canister is and the existence of the EGR port on the carburetor on the car. For the egr port it looks to me from the diagram in FAQ that the advance port and egr port are next to each other but I just see one obvious port there. And I just don't know which port on the charcoal canister is the purge. Assuming I am looking at the right thing there are three ports on top of the canister. Here are pictures. The one of the charcoal canister has the firewall toward the right and the inside of the fender would be toward the top(for directional reference).
Can anyone set me straight on these things? :D
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Mogordo
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Re: Weber carburetor questions

Post by Mogordo »

I'm still looking for help on this, I looked through more posts but didn't quite find many answers. But I did find maybe the egr port is plugged. Like I said; I'm still getting the hang of carburetors. If I don't see a hole right off I assume one doesn't exist...I still didn't figure out which is the purge port either. But now I have more questions too. I'm hoping someone has some ideas. The carburetor was installed when I got the car but it doesn't run as smoothly as I think it can and I wanted to start with vacuum to maybe improve it.
In reading dlb's FAQ guide he says to route PCV valve to intake manifold and that if the original phenolic spacer is intact to leave it set up as it is but if not a new port must be made where EGR used to sit. I don't actually know exactly which piece the original phenolic spacer is and I only think the EGR is still there. I have a picture of that area. If it is do I route the PCV valve to the EGR? Right now it is routed to the port I have marked in purple in the picture.
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SirFoxx
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Re: Weber carburetor questions

Post by SirFoxx »

your phenolic spacer is missing, which is bad. the spacer not only is used for the pcv connection, but its also used to prevent heat soak and vapor lock of the carb. ask around on the facebook page, someone should have one for sale.

without seeing a video, you may be chasing a red herring with you thinking "it isnt running smooth enough". its an old clapped economy engine. you cant expect them to run smooth as butter.

whenever i do a weber swap, i only connect the pcv and the vacuum advance. unless you have to deal with emissions, theres no reason to dick around with the purge and charcoal canister.
1988 DLX 4wd Tercel Wagon w/ weber (RIP)
1985 4wd Tercel SR5 (RIP)
1986 Base 2dr Hatch (RIP / PARTS)
1986 DLX 4wd Tercel Wagon with ???
1985 DLX 2dr Tercel Hatch w/manual swap
1981 2dr Toyota Tercel w/7age (RIP)
1981 3dr hatch Toyota Tercel w/Turbo 4AGE
1981 3dr hatch Toyota Tercel SR-5
Mogordo
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Re: Weber carburetor questions

Post by Mogordo »

Thank-you, at least I know the spacer is missing and that is something to fix. I don't have a facebook account so things on there aren't very accessible to me. Maybe I'll ask on here. Do you know how much height it will add? Just thinking if the carb will still fit under the hood since it sounds like they sometimes don't very well.Yeah, I don't expect it to run very, very good or anything and this is only my second carbureted car but I'm pretty sure my expectations are not too high. Could be carb adjustments too though. Even if it was adjusted well when I got it (though I'm doubtful considering how the vacuum was/is routed) the climate here is different and that could make some difference.
Thank-you again, I'm going to think on and look more into the spacer issue I guess.
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SirFoxx
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Re: Weber carburetor questions

Post by SirFoxx »

you have to use the shorty air filter for it to fit under the hood.
1988 DLX 4wd Tercel Wagon w/ weber (RIP)
1985 4wd Tercel SR5 (RIP)
1986 Base 2dr Hatch (RIP / PARTS)
1986 DLX 4wd Tercel Wagon with ???
1985 DLX 2dr Tercel Hatch w/manual swap
1981 2dr Toyota Tercel w/7age (RIP)
1981 3dr hatch Toyota Tercel w/Turbo 4AGE
1981 3dr hatch Toyota Tercel SR-5
Mogordo
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Re: Weber carburetor questions

Post by Mogordo »

All right. I think it might be the short one but not sure. Thank-you.
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Cadendoo22
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Re: Weber carburetor questions

Post by Cadendoo22 »

SirFoxx wrote: Mon Nov 21, 2022 5:54 am your phenolic spacer is missing, which is bad. the spacer not only is used for the pcv connection, but its also used to prevent heat soak and vapor lock of the carb. ask around on the facebook page, someone should have one for sale.

without seeing a video, you may be chasing a red herring with you thinking "it isnt running smooth enough". its an old clapped economy engine. you cant expect them to run smooth as butter.

whenever i do a weber swap, i only connect the pcv and the vacuum advance. unless you have to deal with emissions, theres no reason to dick around with the purge and charcoal canister.
I've never been able to figure out how to connect the Weber to the vac advance, can you elaborate?
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dlb
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Re: Weber carburetor questions

Post by dlb »

Cadendoo22 wrote: Tue Nov 22, 2022 12:28 pm I've never been able to figure out how to connect the Weber to the vac advance, can you elaborate?
#14 in the FAQ: viewtopic.php?t=7442
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Petros
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Re: Weber carburetor questions

Post by Petros »

the PVC valve should not be connected to the EGR, they perform separate unrelated functions.

I think perhaps sorting out your installation it might help to do some homework: read the chapters in the FSM on how each system operates. From there it will I think become easier to figure out how to make it work in your installation, and what you can safely delete without consequence. Many of the system can be removed when you swap out the factory carb for a weber, but some of the systems need to stay in place to help it run better.

Good luck.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
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dlb
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Re: Weber carburetor questions

Post by dlb »

Petros wrote: Wed Nov 23, 2022 5:50 pm the PVC valve should not be connected to the EGR, they perform separate unrelated functions.
I believe they were referring to Splatterdog's EGR -> PCV conversion, for people with Weber carbs who need to remove the phenolic spacer (with its PCV port) in order to clear the hood.
Mogordo
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Re: Weber carburetor questions

Post by Mogordo »

I was wondering for both the conversion and egr alone, so sounds like if egr is still there it's no good, only if the egr is gone and the conversion has been made for a new port is that a good routing. Petros, I too think it would help if I understood the system better. I'll continue to see about grasping how this system works but understanding some things even rudimentarily can take me a while. I look at it and have no clue, I read things and am confused, I ask questions and it helps, I look at it again and maybe understand a smidge more, I read more and maybe kind of understand, I ask more questions and realize I probably don't understand, I look at it again...Sigh. But I like old cars and I keep at it even if I progress very slowly at times. I did at least route the vacuum advance on the carb to the vacuum advance port off dist. (Though I had trouble with the simple test to see if diaphram was good. It was inconclusive for me despite it's theoretical simplicity.) after removing it from where it was ported with a "t" into the line going from pcv to what I guess is a port off of charcoal canister. And the car is operational so that is something. Thanks :) I'll see if I get to understanding at least a little more this weekend.
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Petros
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Re: Weber carburetor questions

Post by Petros »

both the EGR and PVC systems are fairly simple to understand, they were put on cars a very long time ago, and are still in most modern cars too.

really old antique cars used to just vent the crank case to outside air. the slight bit of combustion gases seeping past the rings would get vented out to the air, causing pollution of unburnt fuel and partial combustion products (very bad to breath). So the Positive Crankcase Ventilation (PVC) system was invented to stop it. It just draws air from inside the air filter (filtered clean air so it does not contaminate the engine oil with dust, pollen, etc), and the crank case air gets cycled back through the intake manifold, where the unburnt fuel is consumed in the combustion chamber. It can slightly improve fuel economy, and if working properly has no effect on the operation of the engine. it is really a good "win-win" for the environment, and for the car owner. I decades ago I had a 1949 Willis wagon, and a 1958 volvo 444, neither had a PVC system. But later I bought a 1965 (and a 1963) Volvo 122S that had a PVC system. so it was about 1960 it became mandatory.

On the PVC system, there is a hose from the air filter that goes into the valve cover, and another one from a one way check valve (known as the PVC valve), and that one runs it into the intake system. it mostly is maintenance free and works okay, cleans the air and uses unburnt fuel that otherwise would go into the air. but if you get a lot of blow by, from worn leaky rings, or the PVC valve is stuck or not working, it will draw engine oil into the intake, lots of smoke, and make an oily mess in the air filter and carb. It is a simple system and easy to check, see the diagrams in the FSM and it should be easy to understand how it works, and follow the directions to check and test it, and fix it if necessary.

the EGR, exhaust gas re-circulation, is also a simple concept to reduce emissions. As I recall it was first used in the 1970s and 1980s on some models, some of the cleaner and better designed EFI engines did not have them until the late 1990s. Now I think all cars have them it built into the fuel and intake systems. With the EGR system, there are higher emissions at peak pressures and temperatures, at certain operating conditions, and the EGR lowers these peak temps in the combustion chamber. by taking some of the exhaust and running it back into the intake manifold it would bring the peak temperatures down, since the exhaust is mostly inert (most of the oxygen used up, and all the fuel burnt away). it dilutes the intake fuel air mixture so the peak pressures and temperatures during combustion are lower, to reduce these certain emissions. It does not run all the time, but the various vac lines and switches on it make it work only at certain operating conditions (when the air temp is high, the engine is fully warmed up, and it is at full throttle as when accelerating hard to pass). It also has the effect of reducing the peak power output, but should not affect operation at part throttle conditions as in most all normal daily driving...when it is working properly.

the problem is the system tends to get fouled with carbon, the EGR valve gets stuck, diaphragms get worn out and leaky, the vac lines get plugged up, or get damage or leak as it ages. Than it harms the way it runs all the time. That is why many remove it on older cars, you can not find replacement parts on obsolete old cars. And there is no operational consequences to just removing the whole system. if it is malfunctioning, removing it will greatly improve the way it runs . Removed, it will lightly improve max power and can noticeably improve the economy. But it is not a bad system when it is working properly for most driving conditions, but as the car ages and becomes obsolete (like our Tercels), it is difficult to keep the system operational.

Now, if you study the FSM on the section about the EGR system it should be easier to understand with basic knowledge of what it is doing.

The PVC and EGR are different unrelated systems, that is what confused me about tying the PVC system to the EGR system. but DLB reminded me of Splatterdog's adaptation. he was not connecting the systems, he deleted one system, and used the old EGR port to install a new PVC system that will work with his weber conversion. Which you can certainly do, hopefully with some understanding of how they work you can get it all installed properly. Many just remove both systems when they swap out the stock carb for a weber, but good for Splatterdog for keeping an operational PVC system in place.

My EGR system is disabled, it never worked properly since I have owned it. I should just completely remove it and get it out of the engine compartment. It will make it a lot for routine maintenance with it out of the way. I will need some threaded plugs to fill the connections on the intake and exhaust manifolds, so I never bothered.

I hope this helps.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
Mogordo
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Re: Weber carburetor questions

Post by Mogordo »

Yes. Thank-you, It did help. Though there are still many holes in my understanding I read through it a few times and do understand a bit more now than I did. Looking at the FSM I think my car does not have the EGR vacuum modulator anymore. The lower port on the EGR that I think would have routed to that is capped off. The port on the top of the EGR was routed into the line going from upper port on vacuum advance unit to manifold vacuum port. I capped that port on EGR and "t" that was used to route it into the other vacuum line. I'd guess that is better since I'd guess having components missing would place the EGR system into the malfunctioning category. It sounds like creating that replacement port would mean comitting to fully removing EGR valve and plugging some holes besides actually creating a port.
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Mogordo
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Re: Weber carburetor questions

Post by Mogordo »

It took me a while to get to it but a couple weeks ago a friend I work for made a port for me (It's not as pretty as some of you have but it works, I think) and I pulled off the EGR. Thanks to information I found on here I got a 20mm ×1.50 oil drain plug bolt beforehand to plug where the other end of the metal line went. And fortunately for me that line came out with only a little trouble. I decided to do without the phenolic spacer since finding and installing one sounded like more than I was interested in right now. I replaced the PCV valve and grommet today. Instructions to check the valve included removing it and as the current grommet was in the hardened phase I didn't see that being so simple so I waited until I had grommet, valve, and valve cover gasket on hand and pulled the valve cover off for the removal. The old valve did not rattle the same way as the new one did. I think there is a blow through it test also but I wasn't in the mood to figure that out.
I guess next I'll be on to basic carburetor adjustments and timing check in my quest for better function.
Thanks,
Cari
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