Am I carbing up the wrong tree?

[lostscotiaguy]

Explanation: I just replaced my old keihin (For an 81 4 door, 1751CC, CA version)with one I had gotten from Pick and Pull. I had cleaned the heck out of it (24 Hr Chem dip soak and all), rebuilt it (with a NAPA kit that had MOST of the seals and diaphragms) and set all the adjustments as so:

Main Idle Mixture = 2 turns out from seated
Aux. Idle Mixture = 1 3/4 out from seated

Floats= Carb "top" held upside down (At diagonal angle), floats resting against needle valve but not compressing springs in needle valve, I.E. 38 MM for large float, 34 MM for small one.

Now, after installing the "new" carb nothing worked as it should and i've managed to fiddle with the main idle mix adjustment to the point where it runs ok. I've left the floats alone, and just barely leaned my Aux mix out. Aside from some other problems with the choke I've managed to coax a somewhat proper idle out of the beast although it could be improved: It doesn't like to idle @750ish, only around 1000 or higher. Also, when it IS idling properly, I can give it a shot of gas and when the RPM drops back down it usually just stalls, then it doesn't want to start back up unless I mostly cover the main throttle bore by hand (acting as a choke). I'm thinking it runs too rich, but I've tried leaning out the main mix and it doesn't seem to help.

More Problems: When I hit the gas, it's over-revving, when I pop the clutch to shift gears, even though I've let off the gas at the same time, the engine revs for a moment like I just "punched it". If I floor it while in gear, no problems, but if the clutch is in, or it's idling in neutral it will rev like it's an angry Ferrari and it takes a few seconds to "settle down" again.
I've checked to see if my accelerator pump is "over squirting" because it does seem to be running rich but the linkage travel is to spec (about 12 MM) and the seals and diaphragm on it are new.


Extra info: My clutch has been on the way out for a LONG time. I've been grandma shifting (a good 3-4 seconds per shift) for a LONG time because if I even come close to shifting quickly it slips. It seems a long shot, but could this have any effect on my problems?

I know I've listed about 8 million things but I'm just trying to be very comprehensive in my descriptions. I've tried looking through every darn thing I can find on here and everywhere else online I can find any info about this old Keihin (There isn't much at all) but I've had no luck, I'm frankly at wits end with this flippity frackin thing so any help is greatly appreciated!!

[Dr_Snooz]

You sir, are in a lot of trouble. These carbs are notoriously difficult and like to jab you in the eye for no real reason at all. It could be just about anything or many things. It could be a bad part or a badly installed part. It could be some damage to the junkyard carb that you didn't notice. It could be a vacuum actuator malfunctioning or the controller for the actuator malfunctioning. It could be a linkage that you didn't get put back together the right way. My first rebuild of a Keihin was a total fiasco. I had to pitch it in the trash and start over with a junkyard unit. Not even the dealer would touch it and that was when the dealers still worked on them and sold all the needed parts.

If memory serves, there is a device that slowly lowers the throttle from high rpms when you take your foot off the gas (smog control, I think). It sounds like that might be malfunctioning. The poor idle could be a simple vacuum leak.

If you end up throwing it away like I did, I'd recommend seeing if you can get a carb off a later model Accord. They have windows in the float chambers so that you can see the float level. I'm not convinced you can get the floats adjusted properly without those windows. Honda says you can, but I never could. Also, the less you take apart on the next carb, the better. The fewer adjustments you change, the better.

Also, I'm not sure if a Weber swap is an option for you, but we should send as many of those miserable Keihins to heaven as possible.

Good luck.

[lostforawhile]

if you want to get a good rebuilt one already adjusted, try importcarbs.com I used to rebuild them myself, and even with the proper special Honda tools, they are a major pain in the ass to get right, as far as adjusting the float, there was a special set of tools, just for that, anything cvcc is a nightmare to adjust, I'm assuming it's the three barrel keihin?, some things you just have to pay the money to have right, don't throw the old one away, if you get one it's your core, after this many years on the junkyard one, and who knows who worked on it, it's probably pretty much screwed, also what did you soak it in? you can't soak these carbs, there is stuff in there that will be damaged. did the new carb come from an automatic car? if it did there is a dashpot on there that delays the throttle plates closing, this stops the automatic from stalling the engine, no load, engine revs instead http://www.importcarbs.com/

[79cord]

More Problems: When I hit the gas, it's over-revving, when I pop the clutch to shift gears, even though I've let off the gas at the same time, the engine revs for a moment like I just "punched it". If I floor it while in gear, no problems, but if the clutch is in, or it's idling in neutral it will rev like it's an angry Ferrari and it takes a few seconds to "settle down" again.

This especially sounds like the 'Throttle opener', umbrella shaped addition to the carburetor.

a device that slowly lowers the throttle from high rpms when you take your foot off the gas (smog control, I think). It sounds like that might be malfunctioning. The poor idle could be a simple vacuum leak.

Stops revs dropping too quickly if you suddenly release the throttle so unburnt fuel won't get through.

Feels like mine has been playing up too & I should look into it. Seems a pretty vacuum diaphragm device. Sometimes leaves the engine revving away sitting at the lights unless I put it back in gear & let the clutch out a little to drag the idle back down. Fitted to many non-CVCC cars too. Idle might then be set incorrectly trying to compensate.

[lostscotiaguy]

I'd recommend seeing if you can get a carb off a later model Accord. They have windows in the float chambers so that you can see the float level.

I had almost bought one from an 82 but I had been told that it won't "jive" with the smog gear,etc. on my 81....You're from CA so you know the joy of smog testing: did you swap your carb for one with float windows? and did it still pass?


Believe me, If I had the funds right now a new/rebuilt one would have already been ordered. I feel stupid cause I don't remember if I got my new one off a stick-shift or not, I've had it for quite a while.....but I AM going to look in my FSM and see what I can find about that "throttle holding" mechanism. Thanks for all the feedback folks, everyone responded so quickly!


Ahhh Fuel Injection, how do I love thee, let me count the ways.....

[Dr_Snooz]

I ended up swapping in a junkyard unit. It ran well enough to get me to the dealer so I drove it there and had them rebuild the junkyard carb. That probably isn't an option for you anymore as the cars are so old now. I don't really know much about the smog stuff as it's been a very long time since I had that car. You have an '81 (I had a '76) and I don't think there was much difference between the engines on the '81s vs. the '82s. I'll let other 1g owners correct me if I'm wrong, but that's what I remember. That rebuild was a complete fiasco for me. I had just started working on my own stuff and I dove into that carb. Had I done it with the experience I have now, I would have wrestled through it and come up with a good way to tame those beasts. Unfortunately, I can't really give you a good solid answer on what to do now. At this point, I think you have two viable options. One, is to go grab a junkyard replacement for an '81. Get the warranty and keep swapping until you get one that runs. If you go this route, you'll probably end up with a less than perfect carb. They're so old and it's such a hassle replacing them that you'll get one that kinda runs and just choose to live with it. Two, is to go grab an '82 carb. Then spend a lot of quality time making it work. It might be a direct swap. But it could be as difficult as mixing and matching parts between the two carbs and re-routing all your vacuum controls to get it through smog.

I just spent a couple months making an aftermarket carb work on an '86 GMC and getting it through smog. It can be done, but you have to spend a lot of time figuring out how to make it all work. You seem to know enough about carbs that you could probably pull off option 2 but it's up to you.

[lostscotiaguy]

Well, I think I have my mixture and my floats tuned in properly....I didn't follow procedure (since it never f***in works for me anyway) and just "fiddled" till I got it running OK. I DID bend the stop-tab on my accelerator pump, since it had a gap of about 2 cm, so now it doesn't start dumping too much fuel every time I hit the gas. I also don't know how to adjust the mechanism that lets the throttle close slowly when you let off the gas (It was taking too longto ease off the throttle), so I simply disconnected it. I have it idling OK (1000ish) and I can blip the throttle with no run on, and no stalling when I let OFF the throttle. I took it for a test drive and it seems OK, it feels a little different but it's perfectly driveable.

I DO however still have the run-on problem when I go to shift under full throttle. It ONLY does it under full throttle though. So, can anyone tell me what they think needs adjustment? At part or half throttle it works fine, but under full throttle she screams like a banshee and basically "revs for herself". I'll go to shift, and the RPM's will shoot up as soon as I hit the clutch (while obviously letting off the gas). I feel like a moron! If I had been paid shop wages for the amount of hours I've spent tweaking on this carb, I could have bought a new car by now.

I'm broke and currently unemployed so finding the cash to buy a replacement carb is a little out of my reach for now, but when I DO have an extra 200-250$ to spend I think I'm just going to bite the bullet and do it.
A few questions to anyone whose bought one:
Were you able to basically just bolt it on and go? are you a CA resident? were you able to get one that met smog laws? I know that since it's an OEM replacement you don't need a CARB E.O. # or sticker for it, but I don't know that the carbs I see online have what is needed for smog. My FSM shows that there's many differences between the CA models and the models that were sold to the rest of the U.S. but I don't know if there's any major difference between the carbs they used on the different models. I had called Guaranteed Carbs (One of only 2 rebuilt Carb sources I know of) and they said they didn't have a CA model.....so to summarize: is there a difference? and can I just buy one, bolt it on, and send my old carb to the darkest deepest pits of hell to never be seen or spoken of again?
In my dreams I have a set of dual side-drafts....Why is it that Keihin has made cool reliable Carbs for years, and I get stuck with the the red-headed stepchild?

3Barrel keihin

CVCC = Constantly Vexing this Confused Canuck.

[Hazwan]

Sticking throttle cable perhaps? Have you checked the slack? I don't know what else could be causing that considering you already disconnected that mechanism thinggy. Or are you sure that you took the right thing off LOL

[lostscotiaguy]

Sticking throttle cable perhaps? Have you checked the slack? I don't know what else could be causing that considering you already disconnected that mechanism thinggy. Or are you sure that you took the right thing off LOL

Yeah, the throttle cable WAS sticking at one point but I lubed the heck out of it and it doesn't seem to be sticking anymore. I also lubed up the throttle itself and it springs back very quickly and firmly. I'm also about 99% sure I got the right mechanism, I looked it up in my FSM and I also tried a "before and after" with it while the car was still running and I noticed the difference. All I did was disconnect the vacuum hose to it though, so if I DID get the wrong one I can fix it easily enough. Thanks for the suggestions Hazwan, I also see your project continues! You're doing a great job on it man and it looks beautiful as always. I'm very jealous!!! LOL
Take care brother!

[Dr_Snooz]

Nice work! I think you are now the resident expert on Keihin 3-barrel carbs.

I think the throttle cable runs through a plastic sheath inside the cable. If that sheath wears through, it will continue binding now matter how much you lube it. It should be replaced.

Are you in California or Canada? I'm confused by your post. Here's the lowdown on carbs in CA. Every aftermarket part has to be certified by CARB to be legal for sale in CA. If it isn't, it can't be legally sold. That doesn't necessarily mean that it makes more smog or even that it's different from a legal part in any way. It just means the manufacturer hasn't paid the money to have it certified. You can probably put any OE replacement carb on the car and pass smog no problem. The differences between the CA and non-CA carbs are going to be certain bolt on devices that operate in very specific situations to reduce smog. For instance, a device that prevents engine run-on might be missing from a non-CA carb. The CA smog check is supposed to check for any modifications to the factory emissions setup. Honestly though, how is any smog tech ever going to know that the anti-runon device is not on your carb? The tech looks to make sure that the EGR valve, cat and PCV are there and that's the end of the looking. All the carbs are going to deliver the exact same air/fuel ratio to the cylinders. Every naturally aspirated engine runs best on a 14.7/1 air/fuel ratio. Doesn't matter if it's a 4-banger econobox or a W16 Bentley, they want the same fuel ratio. (CVCC runs a little leaner, but the point is that the fuel ratio isn't going to change whether it's CARB approved or not.) Any carb that can deliver the 14.7/1 ratio to your engine is going to get you through a CA dyno smog check unless the smog tech is really into 1st gen Accords and Keihin 3-barrel carburetor tuning in a very unhealthy way. All that to say, you can probably buy one of the non-CA carbs and not have a problem. Will not having an anti-runon device create more pollution? Absolutely, but it will get you past the dyno smog test. I'm not advocating illegal activity. I just hate to see people get twisted every which way by smog laws they don't understand. If it really concerns you, you can see about swapping the missing controls from your old carb to the new one. What WILL get you to fail a smog check is not having those floats adjusted properly. (I adjusted my truck's carb by the smell of the exhaust. LOL) I would choose occasional run-on over a car that runs rich constantly.

I'll tell you honestly though, if you were able to get your carb running half-way decent, you can rebuild your own carb. Just get one with the windows in the float bowl. I don't see any reason for you to go spending a lot of money on a rebuilt. I rebuilt both a '76 (no windows) and an '82 (with windows). The difference was night and day. At least spend the $2 to go down to the junkyard and compare between the two. It might be a simple bolt-on swap. You spend $50 for the junkyard carb, $50 for the rebuild kit and have a new carb for not much money. Probably rebuilt a lot more conscientiously too.

No carb is "bolt on and go." You always need to do some tuning.

Good luck and keep updating us as you progress.

[lostscotiaguy]

[QUOTE=Dr_Snooz;1063494]Nice work! I think you are now the resident expert on Keihin 3-barrel carbs.
QUOTE]

LMAO if THAT's the case then we're ALL in trouble!

Thanks for all the advice! I guess a lot of my frustration in tuning my carb has been the fact that I really haven't had much consistency in my results: Just when it seems to be "purring like a kitten" one day, it will be completely unusable the next.
I am in California and thankfully I know about the smog laws, and stoichiometry and all that: (I graduated with honors at a local automotive technical university and I'm hopefully taking my ASE's soon, but then again we didn't learn much about carbs...) I suppose I always forget the fact that as long as it actually passes a smog test chances are it WILL pass the visual (since the average smog guy wont know what to look for anyway). I did wonder about the carb on the 82 since I'd heard conflicting reports as to whether it would actually physically fit and work, regardless of whether it had all the same vacuum operated "smog doohickeys" as the 81. I know most of them are simply "icing on the smog cake" and don't operate most of the time, at least not enough to have any effect on dyno testing.

I WILL ask one last question though, which I've asked several people but never really gotten an answer to: When tuning my carb, where should I start?
I always figured the order would be: Primary idle mixture, Aux idle mix, then primary float, then aux float. Since all of these adjustments effect idle speed it's a little confusing to me what order they should be done in.
Once again, thanks for all the help! if you know for sure that an 82 carb will fit AND work I think I may just bite the bullet when I get the cash. In the meantime though I need to change my clucth! I've got a new one sitting in the closet (next to a new steering rack) that's LONG overdue for changing. The "fun" never ends!

[lostforawhile]

Snooze, I don't think most smog people people would know one Cvcc carb part from another, they look so much alike, It's not like they turn out experts in these things anymore, the dealers can't even fix them

[1GCustomAccord]

I had that problem once, the thing stalling after an acceleration. I dont remember exactly what the solution was, but was one of the following:

1-There is a emulsion tube in each throttle, when i reassembled the carb i swapped the positions, so the emulsion tube from the 1st was in the 2nd and viceversa. OR

2-The idle air jet was not the proper size (I think 170 was correct for mine).

Just check those 2 areas.

Good luck!

[lostscotiaguy]

Any suggestions for the best place to hookup a vacuum gauge for idle mix tuning? I've been hooking mine up "in-line" with the big vac line that goes to the brake booster but it tends to jump around so much I'm having a hard time really getting an accurate reading (plus I'm only seeing 15" HG MAX). I don't know if this is from a crappy gauge or a vacuum leak? All I know is it jumps around a lot and I'm not really getting good results. I'M SO fed up with my F%&*in carb it's not funny. I've been having this battle for more than 8 years. I know I should buy a new one, swap with a weber/swap with an 82 carb, etc. But I just don't have the cash. I'm really starting to become a "non-believer" and I'm close to being tempted to sell/trade my Accord for something post-88, when most Hondas became a lot easier to work with and still actually have access to aftermarket goodies. I know I'd regret it immensely but I'm just worn out. I feel like the only person on here that doesn't know what they're doing, and I'm freakin ASE trained! I have an almost completely rust free Accord with good paint, a straight body, new clutch, reasonably fresh interior and strong engine....it just wont breathe properly! Then I see guys like Hazwan who have taken a P.O.S. Rustbucket and managed to turn it into gold! I started way ahead of the game, and I'm STILL behind. I do a lot of work on other people's cars and I always manage to fix it, but the minute I work on mine, nothing works, or it doesn't work consistently. Sorry to rant folks, but I'm "Losing it".

[lostscotiaguy]

On the other hand: Stay tuned....I'm putting together a really cool post, which hopefully wont have too many pics....I don't know what the rules are so I'm just gonna try and post em, and hopefully it'll work!

[1GCustomAccord]

Maybe your vacuun meter is too sensitive, there are meters with a dampering device to avoid vibrations, maybe is a filter or something in the vacuum line. Dont give up on your 1g, there is only a few details to have a perfect example of a mint condition classic Honda, a valuable piece of automotive history.

[Dr_Snooz]

We've all been there man. Take a break. Drink some beers. Smash something inexpensive. Clear your head then hit it again. You can do it.

It really sounds like your frustration stems more from a lack of funds than anything that's wrong with the car. You probably know this already, but buying another car will probably not do much to fix that.

[lostscotiaguy]

It really sounds like your frustration stems more from a lack of funds than anything that's wrong with the car.

Yeah, I think you nailed it right there.