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3bbl Keihin repair/rebuild/adjust
It seems that carb care is becoming a lost art. Especially with these weird cvcc carbs that Honda and Keihin came up with. The only guy in town I trust with my carb just retired, and I'm thinking if I want to keep driving this car, I'm gonna have to learn to do the carb myself.
Here is the original carb off my 80 Civic wagon. Its a CB13C set up for 48 state normal altitude and A/C. This pic was taken around 2002, just before it got replaced. https://cimg6.ibsrv.net/gimg/honda-t...3f9c5216ac.jpg Its been sitting in my basement for the last decade or so, and I found it a couple months ago, and thought I'd start researching how to get it working again. Research has been slow and challenging, but I've managed to find enough info that I think I'll be able to adjust it properly once its back on my car. If I'm successful, I'll do a video and write-up on it. Hopefully it will be helpful to the other weirdies out there like me, who still love our old clunkers. :) |
Re: 3bbl Keihin repair/rebuild/adjust
Here's some potentially useful things about this carb.
It has 3 barrels; Primary, Secondary, and Auxiliary. The Primary and Secondary barrels work just like they do in a 2 barrel carb. The third, Auxiliary, feeds the cvcc pre-fire chamber in each cylinder. https://cimg2.ibsrv.net/gimg/honda-t...636e4576f5.jpg The primary a/f mixture screw is located on the back of the throttle body, between two larger bracket screws. Above it, is a plug that looks like a screw, but in fact, does nothing. https://cimg9.ibsrv.net/gimg/honda-t...5ab8c90606.jpg This carb also has an aux. a/f adjustment screw on the front of the carb body. This adjusts the third barrel, which sends a relatively rich mixture to the pre-fire chamber in each cylinder. Above this mixture screw is another plug that looks like a screw but isn't. Doesn't adjust anything, although, it looks like people have tried in the past. https://cimg0.ibsrv.net/gimg/honda-t...0a79975736.jpg The linkage on the left of this picture is known as the Lambda linkage. It synchronizes the Primary and Auxiliary barrel valves. They say you should never adjust this, as there is no way to set it right without a special tool. It doesn't need to be messed with during a rebuild anyway. Here's the reason for this carb's retirement 15 years ago: https://cimg8.ibsrv.net/gimg/honda-t...8df8d17c3d.jpg A broken float pin arm. I'm going to try to repair it with some gasoline resistant epoxy. |
Re: 3bbl Keihin repair/rebuild/adjust
A reference pic to remind me of where all the parts under the gasket go.
https://cimg2.ibsrv.net/gimg/honda-t...1392b713d0.jpg For cleaning aluminum and brass, I like to use a solution of water and Pine Sol. I heat it to just less than boiling, and soak all the metal parts a while, then use an assortment of brushes to get the more stubborn spots clean. The rubber and plastic bits can be cleaned in this solution too, though I don't soak them. Just a few quick dips and some brushing works. https://cimg5.ibsrv.net/gimg/honda-t...04170d2da2.jpg After cleaning, I use carb cleaner spray to make sure all the little channels in the top, main body, and throttle body are clear and clean. Also some of the peripheral parts have small channels and even some check ball valves. Good idea to clear those out with carb spray too. A couple of mine had gotten full of black crud. https://cimg6.ibsrv.net/gimg/honda-t...d84adac1dd.jpg |
Re: 3bbl Keihin repair/rebuild/adjust
Float pin arm repair with gas resistant epoxy.
https://cimg9.ibsrv.net/gimg/honda-t...377f2a5847.jpg Home made alignment pin to replace the missing one. https://cimg6.ibsrv.net/gimg/honda-t...88dc36b1f5.jpg Some useful info stickers from under the hood. Still in good shape after 35 years! https://cimg8.ibsrv.net/gimg/honda-t...57cf8adac7.jpg https://cimg6.ibsrv.net/gimg/honda-t...eb3ecf770c.jpg |
Re: 3bbl Keihin repair/rebuild/adjust
I've got my carb reassembled. I made a long boring video on how I done it:
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Re: 3bbl Keihin repair/rebuild/adjust
This is extremely helpful, as I'm about to rebuild my CVCC carb soon. Thanks for the write up!
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Re: 3bbl Keihin repair/rebuild/adjust
Excellent information on carbs and the black art of rebuilding them.
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Re: 3bbl Keihin repair/rebuild/adjust
Tanks guys!
It may be a while before I can do an adjustment write-up. My 80 Civic is my only car at the moment. Other than the 81 that I bought for parts. Speaking of the 81, I decided to go ahead and pull that one's carb out and do a repair and rebuild on it just for fun. Here's a video of that. Sorry about the rain. It rains here about 6 months out of the year. |
Re: 3bbl Keihin repair/rebuild/adjust
Next rebuild is a Keihin from an 81 Civic Wagon.
Not sure how I'll use it, but It can't hurt to have an extra carb rebuilt and ready to go. https://cimg9.ibsrv.net/gimg/honda-t...57a1487712.jpg https://cimg1.ibsrv.net/gimg/honda-t...25ccbbdd47.jpg |
Re: 3bbl Keihin repair/rebuild/adjust
81 Keihin disassembly, Part 1:
Different camera with Higher resolution, wide angle, better sound. Part 2 coming soon... |
Re: 3bbl Keihin repair/rebuild/adjust
Here's part 2:
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Re: 3bbl Keihin repair/rebuild/adjust
Received the rebuild kit from Walker
https://cimg1.ibsrv.net/gimg/honda-t...48b25c2640.jpg The instruction sheet that came with has more details than the last kit I bought. https://cimg3.ibsrv.net/gimg/honda-t...573a6c8c0c.jpg I'll be using this kit on the 81 Keihin I got off the parts car. I'm currently cleaning up the main components as well as taking apart the peripherals. I decided to do a series of pictures for this part instead of a video. I think labeled pictures will get the info across better for these parts. Here's what I've got so far: https://cimg3.ibsrv.net/gimg/honda-t...10b45aa263.jpg https://cimg5.ibsrv.net/gimg/honda-t...475cc071aa.jpg https://cimg7.ibsrv.net/gimg/honda-t...de55a732a4.jpg https://cimg8.ibsrv.net/gimg/honda-t...3f1f01c75c.jpg https://cimg2.ibsrv.net/gimg/honda-t...eabce36a26.jpg |
Re: 3bbl Keihin repair/rebuild/adjust
This thread is just too perfect. I might have the opportunity to pick up a 1975 CVCC myself and I am glad I found this thread just in case i want to try the lost art of rebuilding a carb.
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Re: 3bbl Keihin repair/rebuild/adjust
Here's a few more:
https://cimg4.ibsrv.net/gimg/honda-t...26f42826fc.jpg https://cimg7.ibsrv.net/gimg/honda-t...72f8f553ee.jpg https://cimg8.ibsrv.net/gimg/honda-t...29ba2d1213.jpg https://cimg0.ibsrv.net/gimg/honda-t...5f26eaad4b.jpg https://cimg3.ibsrv.net/gimg/honda-t...ad107d73a1.jpg https://cimg4.ibsrv.net/gimg/honda-t...9a207cd0d2.jpg |
Re: 3bbl Keihin repair/rebuild/adjust
This is impressive and goes a lot further than most would dare to venture.
There is one caveat and that is the mass of hoses, control boxes etc. that for the most part do not function as intended not to mention today's lousy gas. If one is lucky and not tied down to strict emissions standards, a Weber replacement is a relatively cheap and effective route to go though so far I have not done so. My daily driver is an '82 Civic hatch automatic which just turned over 192 K miles. I have begun the first stages of de-vacuuming the unit simply by unplugging all three control boxes. Regarding the carb(s), I have a pretty good Honda guy who hates to work on the 3bbl EPA "inspired" CVCC systems but will do so 'cause he's a mite bit desperate. It's also worth mentioning that the later '82/83 Gen II Civics carbs have float level windows that takes the guesswork out of that adjustment. As an aside, I have a couple of '81 carbs out of cars that have long passed into their new lives as beer cans etc that I would be delighted to donate to your collection for shipping costs. Finally, currently there is an '83 Honda wagon being parted out from a junkyard in Nevada. It is white and currently listed on eBay and I have purchased a couple of trinkets just to have as spares. Good write up! |
Re: 3bbl Keihin repair/rebuild/adjust
Finally got the last few done. Dismantling the choke was a little challenging. A couple of those screws were really stuck!
https://cimg8.ibsrv.net/gimg/honda-t...368317ff08.jpg https://cimg9.ibsrv.net/gimg/honda-t...22d43cb7e3.jpg https://cimg0.ibsrv.net/gimg/honda-t...f9d93aa427.jpg https://cimg1.ibsrv.net/gimg/honda-t...8d0031ab77.jpg https://cimg2.ibsrv.net/gimg/honda-t...7a73caa819.jpg That's it for disassembly. Not sure when, but my next post should be about installation and adjustment. |
Re: 3bbl Keihin repair/rebuild/adjust
I got all the small parts separated into metal only, vs. stuff with rubber/plastic/electrical.
https://cimg7.ibsrv.net/gimg/honda-t...431f51c7f1.jpg I'm pretty sure I forgot to cover this in the videos I made, so here is how to test the electric choke. Measure resistance. As long as you get some real number, it should be fine. That's what I've read anyway. https://cimg9.ibsrv.net/gimg/honda-t...83bbc3ac74.jpg Finally, all the parts are clean and ready for reassembly. https://cimg2.ibsrv.net/gimg/honda-t...bd1be7f014.jpg |
Re: 3bbl Keihin repair/rebuild/adjust
Could be just me, but riveting the choke back together seemed kind of dumb. So I did a little modifying:
https://cimg6.ibsrv.net/gimg/honda-t...e69b860b34.jpg https://cimg9.ibsrv.net/gimg/honda-t...b180e02c5d.jpg https://cimg0.ibsrv.net/gimg/honda-t...ee2952e40f.jpg https://cimg1.ibsrv.net/gimg/honda-t...8c44c2f550.jpg https://cimg2.ibsrv.net/gimg/honda-t...5097413182.jpg Breaking out the rebuild kit. I wish they included the accelerator pump dust cover. https://cimg1.ibsrv.net/gimg/honda-t...a944339002.jpg https://cimg3.ibsrv.net/gimg/honda-t...7563c7b9a4.jpg Finished! Here's the 80 and 81 side by side. https://cimg4.ibsrv.net/gimg/honda-t...844f15eb67.jpg |
Re: 3bbl Keihin repair/rebuild/adjust
Great job!!! I am rebuilding some carbs too and this is great inspiration!!
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Re: 3bbl Keihin repair/rebuild/adjust
Hi folks,
It's been a year, but I've finally made some progress. So not long after my last post, my engine bit the dust. I was barely able to get it to the mechanic under its own power. Based on some diagnostic testing and exploring, it likely had worn out valves and rings, and needed to be rebuilt. After 257,000 miles, I suppose that's reasonable. It took awhile for me to save up the money, but I finally did. Not only were the rings and valves bad, but one of my piston rods was bent, and the camshaft was worn down pretty badly too. Also, it turns out the head gasket was leaking, so there was coolant in the oil, as well as a plethora of other issues. The biggest challenge for the rebuilder was to find new head bolts. He finally cross referenced some from a newer Honda engine (I never did find out which one.) and somehow sorsed a new piston rod. Anyway, that took quite a while but the engine is back in the car and runs great! I actually got a chance to try out the original 1980 carb I rebuilt. My mechanic swapped it out for the one that was on the car just before the engine rebuild. Turns out carb #2 (I don't know what year or model it is) was clogged up somehow. Anyway, my rebuilt original carb did ok. There was a dead spot halfway through the throttle, and it was very hard to start when the engine was warm. It also liked to stall when in neutral. It was suggested that there was a partial clog in the primary jet maybe. Haven't had a chance to find out though, as the engine stalled last month and won't start at all now. I know I've got spark and compression, as a little starter fluid will let the engine kick over a bit. And there's fuel up to the carb. So its gotta be a carb issue, right? I've decided to clean up carb #2, which has been working great for about 15 years, and reinstall that. I've also decided to take the opportunity to make some better videos of how I go about it. These will hopefully be better quality, better lighting, shorter, more to the point, and broken up into more segments. So here's the first: By the way, huge thank you to Grumpy One for sending me two (2!!!) carburetors! |
Re: 3bbl Keihin repair/rebuild/adjust
I finally got some cash together for a rebuild kit. So I'm going to be able to do a proper job after all! Found two reasonably priced kits on eBay and bought both.
Also, I think I've mentioned that I'm working with multiple carburetors. So It may be confusing as to which one I'm referring to in my posts. So here's a list and a brief history of each:
I've got the second installment of my rebuild done. Now that I've got a rebuild kit coming, some of the parts I've reused in this video will be replaced with new ones. I'm quite excited and relieved by that. Reusing the old gasket and o-rings really wasn't sitting well with me. |
Re: 3bbl Keihin repair/rebuild/adjust
Making progress:
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Re: 3bbl Keihin repair/rebuild/adjust
Ok, this next post is to list all the online stuff I've been able to find so far pertaining to these carburetors and how to adjust them.
HONDA KEIHIN CARBURETOR REPAIR A great 1 page site that has info on 3 barrel history, troubleshooting suggestions, and adjustment instructions. https://civicminded.wordpress.com/20...rburetor-work/ This is a blog from a fellow repairing a 2bbl Keihin. I found in relevant because it also has a power valve, and apparently if it gets stuck closed, it can cause a fuel shortage to the engine. He modified his so the valve would be forever open. He never completed the blog though, so we'll never know if it worked. But he has some good info and took some nice pictures. http://1stgencivic.com/forum/download/file.php?id=11314 These are some scans in pdf format someone here made of a repair instruction manual. Lots of good info. https://performancetechnician.com/?s=Keihin There is a fellow who wrote two articles for this website about our carburetors. These are tips and procedures that he got directly from carburetor technicians. This is a fantastic source of information! You have to register (for free) to get these articles, but I cheated a little and put them in my DropBox: https://www.dropbox.com/s/1kph41lcc9...ician.zip?dl=0 |
Re: 3bbl Keihin repair/rebuild/adjust
I was doing some reading here and there, and saw a suggestion to check the solenoid circuit to make sure the fuel starvation is not coming from closed solenoids. I was finally able to get out and do that today. They seem to work fine, so the issue must be inside the carb. Oh well, worth a look anyway.
Carb rebuilding has been slow, but I've finally got another video done, and all the peripherals except the choke are now cleaned up and reinstalled. So then, here is video #4: |
Re: 3bbl Keihin repair/rebuild/adjust
I was able to verify that all the electrics are working in my car. Including the cut off solenoids. I've also finally got the car moved into the bay where I'll be able to work on it sheltered from the weather. Here's a (relatively) short video of me moving the car. I hope you all find it entertaining.
Next up will be finalization of the carburetor, I think. I also need to add some lighting and wind protection to the work bay. It's just a flat spot under my deck as you can see in the video, so its not as protected as a proper garage would be. |
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