Carb swap, pictures and issues

[irowiki]

Alright, finally changed out the carburetor on the sedan with a good running one Petros had field tested. Was my first time doing so, and what a job it was! Spent all day sunday with the wife (Big thanks to Vienna!) taking apart the crap one, cleaning mounting surfaces, installing all the vacuum line and the hooking up relevant devices.

Pictures here, will have some of them in the thread.

Of course, there are issues, as I expected. First, the pictures, click the link above them if they don't display right, or try making your window wider.

Before the swap. In a way I'll miss how open this engine bay was! I won't miss the really crappy cold starting though. The secondary wasn't really attached to anything and could flop open at any time, which I would guess would account for some of my crappy fuel economy.


Intake manifold cleaned off. So there were two old gaskets sandwiched together (and dryrotted), and on the heat shield spacer they used a liberal amount of gasket sealant, it is no wonder the thing seeped gas/gunk!


Installing hardware. "New" TVSV, BVSV, swapped for a three port gas filter (turned out I didn't need it as the hard line covered the vacuum advance and the TVSV) and of course the previously missing hard lines!


Gaskets from a rebuild kit. This was one of the things I flew by the seat of my pants on. Did I do these gaskets correctly? The top and bottom ones match. There was also one without the "rings" that seemed to match a second gen intake manifold.


Almost done! The HAC went where one of the EGR valves would have gone. I don't have a place to hook up the mixture control valve yet, it is supposed to go into the main EGR valve. Any ideas? I know I saw a picture of a hose hookup that went in place of the EGR valve somewhere... maybe for a weber setup.


Anyone up for some spaghetti? The fruits of over eight hours of labor. EGR and AS systems were omitted. Evap system isn't in yet, need to figure out how to operate a computer controlled valve or find a 1st gen can. Blocked off the big evap line going to the carb for now.


We had some problems, using 82 california hard lines with a second gen federal carb and random vacuum bits from two 82 tercels and some second gen tercels. Most of the time we spent was tracing hard lines out. Found it easiest to focus on things one carb or TVSV port at a time. We hooked most things up how they would have been on a Canada Manual Transmission 4WD Wagon.

The amazing thing is, she started right up after the swap. This morning, when cold (25 degrees F) she started first try, which never happened with the old carb! The choke properly opened after the car was warm too.

Now, the issues we've seen so far, I have no idea where to start on these!

The idle is very erratic. It'll idle fine (but seems to be idling high), but then it hunts around, almost dies, catches, repeats. Does the same thing if she's cold or hot. I tried turning the idle down and she just dies instead of catching and staying running. Will throw a tach on her tonight and see what the current idle RPM is. Will also check for vacuum leaks tonight, was too late to do any checking last night.

The throttle is out of whack. It acts like it isn't retracting all the way, at "idle" there's still some pedal flop (for lack of a better word) and it almost feels like WOT isn't quite wide open. I did swap the bell crank from the old carb. What do I need to adjust?

Fast idle doesn't seem to work. Are there supposed to be any springs in there? I have the throttle return spring and that is it!


After I iron all these issues out I'll probably tackle returning the fuel system to stock.

[dlb]

the erratic idle is likely a vac leak. quintuple-check that all those lines are correctly hooked up but i'm actually going to guess that it's those gaskets above and below the phenolic spacer. i believe the spacers i have seen had gaskets permanently adhered to them. you could try just tightening the 4 carb bolts down to start with, though. if the erratic idle improves, i would think about removing those gaskets. also, did you test all the diaphragms already?

sounds like there's too much slack in the throttle cable. try tightening it up a bit.

i'm not clear on how the fast idle cam works so i will be interested to see what you find there.

good luck, paul!

[irowiki]

Oh, the gaskets are for if there's no spacer? Should I use RTV sealant? So it'd be manifold -> RTV -> spacer -> RTV -> carb? The spacer had a bunch of dry rotted RTV style stuff on it that I scraped off.

I tested the diaphragms on the carb, and the vac advance can is brand new. I think the HAC could be clogged too, no idea how to find filters for it. The HIC line from the carb to air filter may be a problem as well.

Nub question, but where is the throttle cable adjusted? I suspect my haynes manual has it so I'll check there.

Fortunately I have two other tercels to compare the fast idle stuff to so that may help.

[dlb]

the throttle cable is easy to find because it's the only cable that goes to the carb. it runs from the driver side firewall to the bell crank and is adjusted using two 12mm nuts found on a bracket near the rear of the valve cover.

i'm honestly not sure what those gaskets are for. like i said, the spacers i have seen had gaskets permanently affixed to them so i never used anything else with them. i never had any problems with seeping or vac leaks at the carb base. so no, i would not use any RTV. but just try snugging up the nuts at the carb base and see if that helps first.

[irowiki]

Ah ha! I remember seeing those bolts too. I wasn't sure if it were those, or something by the pedal inside the car.

Well, oops, so all the crud I scraped off the spacer was supposed to be there? It is just a bare piece of plastic now. I tried to put a second gen CMH spacer on, and it didn't fit down the hole on the intake manifold. I'll snug them when I get home.

Call me crazy, but I didn't see any torque specs anywhere for the carb bolts.

If snugging them doesn't work, and I need to take the gaskets out, what should I do?

[Petros]

DO not put RTV on the cab gaskets! it squeezes out and gets in places it should not. either install them dry, or what I do is put a very light layer of anti-seize on both sides, so when you take off the carb it will come off clean and it can be reused. You need a gasket on each side of each part that goes in there: one between the manifold and the plastic spacer/heater, one on top of the plastic spacer under the heat shield, and one over the heat shield that goes under the carb. Each one is a slightly different design, you have get the order correct or you could block off important passages ways.

[irowiki]

Figured out the gaskets are a giant vacuum leak by spraying carb cleaner on them. Tried snugging the carb bolts to no effect. Why would the gaskets essentially do nothing? Wrong kind of gasket?

I didn't realize there were two heat shields. One for the "hot air intake" and one for the carb. The hot air intake one that covers the exhaust manifold is unusable on the sedan unless I take the entire thing apart, but I think I can use the carb heat shield.

So I should use the same gaskets I'm using now, but go manifold -> gasket -> spacer -> gasket -> heat shield -> gasket -> carb?

Two of the large gaskets in my carb kit are identical with matching round openings for the primary and secondary. The third gasket looks like a big oval that matches the second gen intake manifold.

[Petros]

yes, use the gaskets, you got them on in the incorrect order. there are vacuum ports under the carb that have to have the correct gasket under it, or it will act like a vacuum leak. study it, the correct order should be obvious with some consideration. or you might see if the exploded view of the parts diagram shows enough detail to see (not likely), or perhaps the FSM.

[irowiki]

The parts diagrams in the repair kit lacked showing the large gaskets. The FSM nor my repair guides show anything.

Two of them are identical, the third is different. The one in this picture is one of the two identical ones.
https://lh3.googleusercontent.com/-DYlt ... 123112.jpg

Will take a picture of the third one tomorrow.

Edit. I have two of the gasket shown on the right here:



The third looks kinda like the one on the right here:

[ARCHINSTL]

Check out this link: https://tercel4wd.com/forums/viewtopic.php? ... it=gaskets
I thought 2 of your photos looked familiar! I presume you've read all of this link? https://tercel4wd.com/forums/viewtopic.php? ... 259#p27259
Tom M.

[irowiki]

Tom, yeah, I found those threads, which helped me with the pictures, thank you! Funnily enough though, I did not find those threads with the forum search, I had to go to google and do "site:tercel4wd.com carburetor gaskets"

Your first picture is gone!

Edit 2: Seems 5 of them were stuck in a clump, here's the other gaskets in the kit:

I did use a light coating of red Permatex gasket cement as a precaution.

How light? Just dab it into the surface like Petros suggested with the anti seize? All three gaskets or just the carb one?

possible order

One thing, my intake manifold is different, see picture:



So I may need to use a different "manifold to heat shield" gasket? Or will this one work:



I would think it would work because the heat shield, if it fits, is from a second gen and is one large opening.

[Petros]

I would not use permatex at all, just a light coat of anti-sieze. one thing that also works is use permatex on one side (very light layer), and the anti-sieze on the other side. that way next time you take it apart it will stay attached to one side and come off clean without damage on the the other side. Make sure all of the old gasket materiel and sealant is off of all the other surfaces.

If you are stuck somewhere and have to remove the carb for any reason to do a field repair, you will not damage the gaskets and can reuse them, get it back together and be on your way without any leaking. Using the anti-sieze on the gasket allows for this kind of reusing of gaskets since it allows you take them apart and reuse them without damage.

[irowiki]

Ah, so the anti-sieze will also help seal it some? I'll pick up some today.

Probably going to salvage a dead EGR valve to use it for the Mixture Control connection before I actually take the carb off, as the current bolt plugging the EGR requires the carb be off anyway.

Ideally I'd make up one of those weber style PCV to EGR fittings but I lack the tools to do that.

[irowiki]

Okay, swapped in the proper gaskets and the heat shield. Didn't take pictures as it was dark, cold and the baby was antsy. Stuff went on in this order:

manifold -> anti seize -> gasket -> RTV -> heat shield -> RTV -> gasket -> anti seize -> plastic spacer -> anti seize -> gasket -> anti seize -> carb.

(didn't want RTV getting right next to the carb)

Let it sit 24 hours. Started up car. Still cutting out and RPM hunting at idle, but not as bad.

Looked at carb again, and it looks like the 1st gen and the 2nd gen reversed the fuel cut solenoids. Unplugged the vacuum switch. After that, the engine stopped cutting out at idle, still hunting a bit but more stable.

After some consultation with the wife we decided to disconnect the HAC because it was unknown. Lo and behold the idle settled out! Ordering new HAC filters before I try troubleshooting that.

However she doesn't really want to idle below say 1,100 RPM. The fast idle is also not working. Still need to adjust the TP as well probably.

Took the car out for a drive and let me say having a working secondary is an amazing difference! Feels like it is a completely different car.


Edit, eureka! https://tercel4wd.com/forums/viewtopic.php? ... t=solenoid
Can I just switch the connectors out on the carb wiring harness to match how a 1st gen is wired, or do I need to swap the solenoids? On FU-18 of the FSM, it shows changing the connectors between usa and canada. I would just match the connector on the second gen carb to the connector on the junk carb I took off.

Any ideas on how to fiddle with the fast idle?

[dlb]

the TP and fast idle are easy to set, just use the FSM. since you don't have a tach in the car, you will need to either find a timing light with a tach or just use your ear. i don't mind using my ear for these settings. for the fast idle, i just set it up around what sounds like hwy cruising rpm (about 3000 rpm), and for TP i set it at what sounds like a too-fast idle (about 1400 rpm).

i'm not sure about reversing the solenoid wires. no harm in giving it a try. you can cut the wires and twist them back together temporarily to try reversing them. if that works, i would then solder and shrink wrap them.