120 replies to this topic

[Captain Regular]

cap off the yellows and leave the other two along I belive- I'd need to see it in person


hell i dont even know what you circled in the others- looks like random casting voids to me in that picture

Well, it COULD be just a random casting. At least the top one anyway. If I'm capping the two ports, whatever it is will probably be irrelevant anyway. But I KNOW the one below is the idle mixture adjustment, and that's the one I need to know about. Which way is leaner vs richer? Or how do I tell? I know I can use an "O2 wideband" or a "propane enrichment kit" to adjust my mixture, but can I just...tinker with it? There has GOT to be a simpler way, even if it's not as fast or accurate.

[zakats]

ah... thats right... I wouldnt worry about it at all unless you notice it to be significantly too rich, which I doubt.

[Captain Regular]

ah... thats right... I wouldnt worry about it at all unless you notice it to be significantly too rich, which I doubt.

Ok, I just ran into another problem. My idle screw (which I just took out to clean, like everything else it was pretty dirty) had no O-ring or spring, as indicated in the rebuild kit instructions. The O-ring isn't a problem, as there's a replacement in the kit, but the spring...is it a problem? I'm not sure HOW this screw controls the mixture for the entire carb, it looks like there's just an air passage that goes up through, and it meters how much vacuum is passed up to other, fuel-controlling, parts of the carb. Beyond this theory, this little needle-screw is a mystery to me. Anyway, what the hell do I do? Just put it back together like it was, add the O-ring, or try and find a replacement spring? I might be able to snip one from a Bic pen or something, I don't know if an auto parts store would carry something I could use to substitute, or even how necessary it is...

[Captain Regular]

Ok, I just ran into another problem. My idle screw (which I just took out to clean, like everything else it was pretty dirty) had no O-ring or spring, as indicated in the rebuild kit instructions. The O-ring isn't a problem, as there's a replacement in the kit, but the spring...is it a problem? I'm not sure HOW this screw controls the mixture for the entire carb, it looks like there's just an air passage that goes up through, and it meters how much vacuum is passed up to other, fuel-controlling, parts of the carb. Beyond this theory, this little needle-screw is a mystery to me. Anyway, what the hell do I do? Just put it back together like it was, add the O-ring, or try and find a replacement spring? I might be able to snip one from a Bic pen or something, I don't know if an auto parts store would carry something I could use to substitute, or even how necessary it is...

What's right? I DO worry about it being excessively rich. It was rich BEFORE the devac, and I hear that makes it MORE rich. I now believe a lot of it was due to a poor seal (or none) around the idle screw, and I think I'm going to need to adjust it to be leaner because of all the factors combining to make it rich. I'd like to know how to do that.

Also, I have ANOTHER question, namely about the "mod" to the power valve. Mine was stuck like glue, as well, so I did the same thing DarkHand did. I filed it down (actually, hacksawed, but same effect). On my daily driver, what effects can this have? Even MORE gas into the engine, so leaner still to compensate? I'd rather, where I can, trade off power for MPG. Oh, and what about that red cap on the back of the carb, next to the electrical solenoid that screws in, the one that sat next to where one of the choke apparatus mounting points? Any idea what it does, and cap or uncap?

[zakats]

lets keep in mind the only real a/f adjustability to that carb is it's **IDLE** enrichment screw.

I wish I had an understanding of all the carb's circutry so I knew what it was that actually impacted the a/f mixture when devac'ing but I'd put money it has to do with constant vacuum pulling air through those tubes and being set a little richer than necessary to compensate. I think the richening ought to be very slight and neglidgeable especially if you run a good, free flowing air filter and theoretically you could take one of the lower volume vacuum hoses and connect it to the base of the air cleaner to get that extra bit of air... all in all I really don't think its worth your time to worry about if the carb is working properly.

[DarkHand]

I wish I had an understanding of all the carb's circutry so I knew what it was that actually impacted the a/f mixture when devac'ing but I'd put money it has to do with constant vacuum pulling air through those tubes and being set a little richer than necessary to compensate.

That's pretty much it as far as I can tell, too. Some of the ports that get capped feed straight into the primary and secondary below the throttle plates, and capping them off blocks alot of air, richening the mixture. The air jet controller happens to feed right to these same ports, so I'm wondering if adding it back will help properly meter the airflow through them. The 3geez forum adds the air jet controller back to the carb in one of their Accord devac methods, so I'm looking into that. No real way to tell what kind of a difference it makes without a wideband though.

[Captain Regular]

ets keep in mind the only real a/f adjustability to that carb is it's **IDLE** enrichment screw.

I wish I had an understanding of all the carb's circutry so I knew what it was that actually impacted the a/f mixture when devac'ing but I'd put money it has to do with constant vacuum pulling air through those tubes and being set a little richer than necessary to compensate. I think the richening ought to be very slight and neglidgeable especially if you run a good, free flowing air filter and theoretically you could take one of the lower volume vacuum hoses and connect it to the base of the air cleaner to get that extra bit of air... all in all I really don't think its worth your time to worry about if the carb is working properly.

Wait, what the hell? I thought that quite a bit of actual driving was done on the "idle jet." I think it was from either this thread or the Devac Write Up thread. Because I was wondering how adjusting only the IDLE mix would affect my actual fuel economy in any significant numbers. So, really, the only carb "adjustments" to be made actually ARE the ports and how much air I let in through them? I am now supremely confused. Why is this screw so important if it only controls the mix at idle? IS it that important? It's out now. Like right now. When I took it out, I turned it all the way in and measured how many turns back it was. 5.5 turns out from hand tight, but that was WITHOUT the washer or O-ring or spring that the rebuild kit says should have been in there? Do those things even matter? Can I just tighten it up 1 or 2 turns to compensate? Does it matter? Oh, and what about that port on the back of the carb, passenger side? The one right next to the "idle cutoff solenoid." Does that get capped or opened? I've decided to take apart my air jet controller and hook it back up. Mine seems to have an oily-ish gunk in one of the ports, like something was leaking into it before. I hope there's nothing in there that I can't put back together. DarkHand, opened any up yet?

Edited by Captain Regular, 03 November 2008 - 09:00 PM.

[DarkHand]

DarkHand, opened any up yet?

Not yet.

A quick and dirty adjustment for the idle screw is to turn it in until the idle starts to climb (too lean), then back it out a half turn. A better way is to adjust it for the highest amount of manifold vacuum you can achieve using a vacuum gauge hooked up to the intake. The best way would be with the propane enrichment kit.

Oh and cap that port. Typically you need to cap off all inlets into the carb, and leave diaphragms uncapped to allow them to move.

[zakats]

Wait, what the hell? I thought that quite a bit of actual driving was done on the "idle jet." I think it was from either this thread or the Devac Write Up thread. Because I was wondering how adjusting only the IDLE mix would affect my actual fuel economy in any significant numbers. So, really, the only carb "adjustments" to be made actually ARE the ports and how much air I let in through them? I am now supremely confused. Why is this screw so important if it only controls the mix at idle? IS it that important? It's out now. Like right now. When I took it out, I turned it all the way in and measured how many turns back it was. 5.5 turns out from hand tight, but that was WITHOUT the washer or O-ring or spring that the rebuild kit says should have been in there? Do those things even matter? Can I just tighten it up 1 or 2 turns to compensate? Does it matter? Oh, and what about that port on the back of the carb, passenger side? The one right next to the "idle cutoff solenoid." Does that get capped or opened? I've decided to take apart my air jet controller and hook it back up. Mine seems to have an oily-ish gunk in one of the ports, like something was leaking into it before. I hope there's nothing in there that I can't put back together. DarkHand, opened any up yet?

the idle jet doesnt do much after 1000~1200rpm last I heard.
if you are completely confused then you are on the right track, carburetors are a wacky pseudoscience just like automatic transmissions!

you can get a wideband kit from 14point7.com and wbo2 for about $100 if you want to take the guess work out of all this.

[Captain Regular]

the idle jet doesnt do much after 1000~1200rpm last I heard.
if you are completely confused then you are on the right track, carburetors are a wacky pseudoscience just like automatic transmissions!

you can get a wideband kit from 14point7.com and wbo2 for about $100 if you want to take the guess work out of all this.

This is really the first time I've ever done anything with a carb, and when I got it off and started opening it up, it looked like a gizmo straight out of the Starship Enterprise. I thought "It's just gas and air, they can't possibly need this many parts." If it doesn't work right when I put it back on, I'm likely to start looking for a chipped control crystal or an infected bio-organic hydrocarbon metabolizer.
I did have another idea for adjusting the mix... All those plugged up ports are what's likely to be blocking some air and enriching the mixture, right? What if I UNPLUGGED them and put manually adjustable valves on them... like those little plastic valves from an aquarium, maybe? You'd be able to open each one up a specific amount, maybe letting just a little air in. It would be fixed, and not as...dynamic as the old vacuum control boxes. I dunno, maybe that would be getting TOO complicated, especially when a devac is supposed to SIMPLIFY a carb. I was also thinking about just getting a regular old electric positional servo motor for the choke, too.

[DarkHand]

What if I UNPLUGGED them and put manually adjustable valves on them... like those little plastic valves from an aquarium, maybe? You'd be able to open each one up a specific amount, maybe letting just a little air in. It would be fixed, and not as...dynamic as the old vacuum control boxes. I dunno, maybe that would be getting TOO complicated, especially when a devac is supposed to SIMPLIFY a carb.

I've rolled that exact idea around in my head before. No real way to tell what effect you're having without a wideband controller though.

[zakats]

that doesn't sound bad but from personal experience I know that the car doesn't run that rich to be a problem. I'd just take one of the higher vacuum pressured ports, run it to the air cleaner (there is a small vacuum port on the base of it that receives filtered air) and use a machine or wood screw as a jet of sorts... is it really all that necessary? nah not really, you'd be fine without it- like I said before, just have a nice free-flowing air filter and intake and you should be just fine. I really wouldn't put too much thought into it since the engine IS a "lean burn" design anyways.. you might just run less lean!

[Captain Regular]

that doesn't sound bad but from personal experience I know that the car doesn't run that rich to be a problem. I'd just take one of the higher vacuum pressured ports, run it to the air cleaner (there is a small vacuum port on the base of it that receives filtered air) and use a machine or wood screw as a jet of sorts... is it really all that necessary? nah not really, you'd be fine without it- like I said before, just have a nice free-flowing air filter and intake and you should be just fine. I really wouldn't put too much thought into it since the engine IS a "lean burn" design anyways.. you might just run less lean!

You know, with a wideband setup (which I've looked into but probably WON'T be getting anytime SOON) and some minor mods, one could make a nifty manual mixture control in the cabin, with live feedback as to the mixture. It would take a little skill, but I imagine, with a "customized" mixture for each driving environment and range of engine temperatures, you could probably get a SIGNIFICANT improvement out of overall fuel economy, AND call up some extra power when you want it.... Man, I need to get out of this thread, I am getting WAY ahead of myself.

[86rustbox]

i'm definitely devaccing now. when i got my civic i was afraid to touch the vac system, i'd never seen something with so many damn hoses. reading this thread from the beginning, it has helped a lot. thanks.

anyways, i've rebuilt the carb once (a shitty kit that was mainly just gaskets, not even a float) and ever since then i have an erratic idle between 1000 and 1400 rpm. could this be the float i didn't replace? mix screws? or maybe the fact that i took off the egr system w/header install (plugged all hoses)?

MANUAL CHOKE IDEA: my choke opens too soon after start up and makes for hard starting the colder the weather is...and i've heard about these canadian manual chokes, but i think i'm going to try and purchase a generic lawnmower throttle cable from the hardware store, and try and fit in where the linkage connects to the choke plate shaft, drill a hole in the firewall and mount it up under the dash. sounds macguyver but i think it might work.

last thing, does anyone know where to get or how to make bigger jets? i've heard of doing this on edelbrocks and holleys, but i can't find dick on honda carbs, of course.

[Captain Regular]

i'm definitely devaccing now. when i got my civic i was afraid to touch the vac system, i'd never seen something with so many damn hoses. reading this thread from the beginning, it has helped a lot. thanks.

anyways, i've rebuilt the carb once (a shitty kit that was mainly just gaskets, not even a float) and ever since then i have an erratic idle between 1000 and 1400 rpm. could this be the float i didn't replace? mix screws? or maybe the fact that i took off the egr system w/header install (plugged all hoses)?

MANUAL CHOKE IDEA: my choke opens too soon after start up and makes for hard starting the colder the weather is...and i've heard about these canadian manual chokes, but i think i'm going to try and purchase a generic lawnmower throttle cable from the hardware store, and try and fit in where the linkage connects to the choke plate shaft, drill a hole in the firewall and mount it up under the dash. sounds macguyver but i think it might work.

last thing, does anyone know where to get or how to make bigger jets? i've heard of doing this on edelbrocks and holleys, but i can't find dick on honda carbs, of course.

Well, I got mine done. Devacced AND did most of DarkHands mods. No automatic choke ANYTHINGS, just the plate and (literally) a piece of nylon cord that I have run up by the windshield wipers and in the window. I actually pull a string to help start my car right now. Still debating what sort of choke control I DO want to add, but it will NOT be automatic. I kept the float bowl vent system, just routed the vent line directly, basically wedged the small vac line right into the larger one that was on there before, it makes a pretty good fit. The AC idle boost side is completely off, the secondary diaphragm has been removed (that was a pain, I used a hacksaw and it took a WHILE) and I used the zip tie mod, which works GREAT.
I also tightened the hell (all the way) out of the spring in the little diaphragm that was connected to the regular idle, so I have support for the main idle control screw, but the diaphragm doesn't DO anything other than act as support.
I also did the power valve "mod" (hackjob, really, used a hacksaw ) and we'll see how that affects fuel mileage, didn't seem to have an impact on driveability. If fuel mileage suffers, that power valve is my number 1 suspect, and I'll just plug it up. Since it's called the "power" valve, I assume it provides extra power, which I really don't demand. I'll gladly take a hit on power for a boost in fuel economy.
I didn't RTV on the 3 vac plugs that went to the air jet controller, but it's not on yet, because I want to take it apart (to both clean it out and determine how and what it DOES) but it drove fine with those ports plugged. I'll post more later, probably this weekend on my AJC research.
As for my idle screw issue (I had no spring, washer or O-ring when I dissassembled, just the needle screw) I simply put it back in how it was, but at only 2.5 turns out instead of the old 5.5. After I adjusted the float level and idle speed, it ran fine. I couldn't put the O-ring in because it doesn't fit right without the washer and spring, which I still don't have. If what others have said is true, it shouldn't be that big of a deal. I think the threads seal pretty well. If it proves to be good where it's at, I might take it out, RTV the threads and put it back in in exactly the same spot. MAYBE. I'm leery of putting RTV somewhere where it will be hard to clean out.

The only thing remaining is to finish blocking and taping the air cleaner box, which is like a 5 minute tape job, and blocking off the EGR valve exhaust tube (or MAYBE replacing the EGR valve system, not sure about that yet. Pros vs cons?) because it was unblocked during my test drive and DAMN. Exhaust isn't pleasant.
And I also have to take a look at the components in those old vacuum boxes, I'm SURE there are going to be some goodies in them.