20 replies to this topic

[mickcrx]

hello i have a 1987 crx HF that recently was getting 50 mpg highway. My option now is to get rid of the vac lines and carb , because the system is acting up. My main concern is maintaining the same mpg after the conversion and fine tuning. Is this possible? Weber k726 seems to be the choice of many crx owners. Shall i stick with the norm, or is there another model or brand carb on the market that will get the peak mpg? Please feel free to give any suggestions. I appreciate any help. Mick

[Mark L]

I highly doubt you will get the same mileage with the replacement Weber. The HF is highly tuned for mileage. The engine is only 1.3 liters and there is a low limit on how high you can rev the engine. The Carb is simply too big for big MPG numbers on a 1.3 low rpm engine.

In my opinion, I think unmodified HF CRXs are appreciating, and if you can it would be good to keep it stock. But the reality is these cars are 25+ years old, and the complicated carburetor is falling apart and is really difficult to replace.

Mark

[mickcrx]

My car is a 1.5 motor. How much would this change mpg? Allot? What about the devac write up on this site? I know that the car runs rich atfer this devac, but how would this affect my mpg? Alllot? I get 50mpg when it is tuned right with the system non-devaced, but I am thinking of getting rid f the old emissions etc.

[Bubba]

By having a rich A/F mix around the spark plug and a really lean A/F mix in the main cylinder, the Honda CVCC system is able to run well at an overall lean mixture- this is what gives such good mpg. The Weber is jetted richer so it will be hard to get the same mpg. If you tried to lean the weber out as much as the average CVCC mix, the spark plugs would have trouble igniting the really lean mix.

I devaced my 87 HF and was able to get 47-48 mpg on the interstate. Do the devac and look around for a carb (or jets) from a 1.3 liter- they were set up to run leaner (no oxygen sensor/system to lean the mix out).

[mickcrx]

Wow!, so the devac is just like the right up in the carb section of this site? If I find a 1.3 lt. carb, I can do this? What do I do with my O2 sensors and the single vacuum advance control vacuum hose? thank you for the help. mick

Edited by mickcrx, 27 June 2012 - 02:17 AM.

[Bubba]

I did my devac differently than everyone else since I am looking for the best mileage rather than power.


I ran ported vacuum directly to the EGR.
I ran manifold vacuum to the power valve port on the carb, the distributor advance, air cleaner snorkle preheater control unit and the choke pull off. I also kept the vapor canister and hoses.

I took out both black boxes and the ECU under the passenger seat. You can leave the oxygen sensor hooked up or clip the wires.

Unless you have the 1.3 carb or jets, your mpg will go down a bit if you just devac with the 1.5 carb since the cars with 02 sensors are set up to run a tiny bit rich and it leans itself out as needed as it receives info from the oxygen sensor. The leaning process is done with controlled vacuum bleeds in the black boxes (there are additional tiny air filters in there).

[mickcrx]

Wow , you are a genius! I wish I was more capable of understanding how you did this. I am new at fuel/electrical stuff. I know basics like just taking things apart and cleaning them. Col0r bY NumBeR kind a gUY:) Do you have any pictures? I wish you did a write up like the one for the stock 1.5 carb "Devac write up" on this site (http://www.redpepper...showtopic=36398).

If I did most of the steps done on the write up on this, how much differant is it to do it your way with a 1.3 carb? I have a 1.5, so if I buy a 1.3 carb for my 1.5 car, your procedure will work? You have a 1.5 and put a 1.3 carb in? If I used my stock 1.5 carb and just changed the jets to 1.3 jets (and anything else I may need to change) and do the devac as on the "Devac write up" on this sie, will I get the same mpg as you? Or would it be more beneficial to do exactly as you did?

I am new at this, but I really want to get a 1.3 carb and attemped what you have done, but I have to try and understand what you did.

1. (YOU) I ran ported vacuum directly to the EGR.

(QUESTION) So I am going to put the vaccum hose from the original spot on the 1.3 carb directly into the EGR and delete the electrical wire to it?

2. (YOU) I ran manifold vacuum to the power valve port on the carb, the distributor advance, air cleaner snorkle preheater control unit and the choke pull off. I also kept the vapor canister and hoses.

(QUESTION) So are you saying all I do is run/ keep the original Vacuum hoses from the correct spot on the 1.3 carb (assuming I find a picture of the 1.3 carb) and keep them in the original spot where they connect to the manifold or is a trick? I know that the distributer advance is connected in conjunction with other hoses to some type of a plastic "T" connection. What do I do with the other hoses and plastic "T"? Do I take the wires off the electronic choke and just keep the original vacuum line connected?

3. (YOU) I took out both black boxes and the ECU under the passenger seat. You can leave the oxygen sensor hooked up or clip the wires.

(QUESTION) I just take out the ECU and thats it? Is the carb the only thing that is controlled by the ECU? I have A/C in this car. Is it connected into the ECU? I will just clip the O2 sensor wires. With the remaining unused ports on the carb, would I just cap em off?

Its too bad I didnt know ya a couple months ago. I took REX right through Louisville hitting a wopping 2100 RPMS going 70mph. Great car ! I am after fuel efficiency as well. I would buy a 1.3 carb and do this, but Wow, it is rocket science for me. There doesn't look like there is not many steps to this after I install the carb. If I attempt it and take pics, would you be able to assist me in any way? Did you pay a mechanic to do this? I'm assuming you did it yourself. How long did it take? I appreciate your replies. Thank you, Mick

Edited by mickcrx, 28 June 2012 - 12:05 AM.

[Bubba]

I have a 1.3 so I used a 1.3 carb- but the 1.3 carb jets are smaller than the 1.5 jets so it will run nice and lean.

I do all of my own mechanic work- it took maybe 10 hours to research what to hook up/unhook and only 2 hours or so to actually connect everything.

I'll take pics tomorrow and do a write up this weekend on the devac thread but i can answer some of your questions now.

1. You will run a vacuum hose from one of the 2 ported vacuum fittings low on the back of the carb directly to the egr valve. The electrical connector goes to a position sensor that tells the ECU how far open the EGR valve is- you can just disconnect it or leave it connected- your choice.

2. Leave the choke heater wire connected to the carb- as well as the fuel shut off solenoid wire. You will need to plug the manifold vacuum fittings that are not used- I like to run short loops of hose from one fitting to the next- this seals it and I don't have to worry about little caps cracking over time.

3. You may want to leave the ECU hooked up just long enough to test the A/C. You can just cut or unplug the O2 sensor wires later after you get it running well. Once you take out the black boxes, the oxygen sensor's signal won't matter.

Is the car still running now? If so, unplug the 4 wire connector that goes to the distributor and make sure it still runs about the same (leave the 3 wires that go to the coil connected). If it doesn't then you might need to get a non HF distributor. The 4 wire connector is some sort of computerized advance controller and I had trouble getting my HF distributor timed correctly after I cut the wires (it seemed to be really far advanced so that the adjustment slots wouldn't line up properly)- so I just used a civic distributor.

Read the service manual sections on the fuel system and emissions system- that will give you some background on what everything does. You will also want to clean/rebuild your carb (if you choose to just put the 1.3 jets in) or rebuild the 1.3 carb if you choose to slap another carb on it so be sure that you are comfortable with doing that. It would also be good for you to google manifold vacuum, ported vacuum and venturi vacuum since things won't work correctly if you get those hoses mixed up (you will be using all 3 types of vacuum sources).

I'll post pics and a writeup this weekend in the carb section and you can just follow the pics and do it like I did- I will be happy to answer some questions or refer you back to my write up.

There are still a few 1.3 carbs out there on car-part.com. Maybe someone on here will sell you a 1.3 carb. The 87 civic's 1.3 carb is easily identifiable because it has 2 fewer vacuum hoses on the top cover up near the fuel line.

[mickcrx]

I appreciate your help. There does not seem to be that many steps to this project. You are a genius. Do you suggest I just put 1.3 jets in a stock 1.5 carb, or can I just slap on a 1.3 carb with no issues before I attempt this procedure? By what yu explained, I'm assuming the 1.3 carb is compatible with my motor. I figure in order to do exactly as you, I would need a 1.3 carb so that the ports on the carb etc. are all the same. If the only physical difference in both carbs is only 2 vacuum lines on the top (1.5), then the rest of the carb must be close to identical? By getting a stock carb and just changing the jets will I have the same mpg benefit as if I put a 1.3 carb in? I am trying to figure this out before I buy a new rebuilt carb on nationalcarburetors.com because my carb is old as the hills. Thank you much

Edited by mickcrx, 28 June 2012 - 10:44 PM.

[Bubba]

The 1.3 and 1.5 carbs bolt up the same. The only thing that is different is the fewer hose fittings on top, the jets and the venturi is a little smaller on the 1.3 carb. Be careful about buying a new/rebuilt carb- make sure they can prove with the model numbers that it came off a 1.3 and not a 1.5 (they can just slap the top of a 1.3 carb with fewer vacuum fittings onto a 1.5 carb and no one would be the wiser unless they knew the model numbers). You should be able to find a 1.3 carb on car-part.com and get a rebuild kit for less than $50.

Is your car running/idling now? Does the shift indicator light work properly?

[mickcrx]

My car is running now and idling at around 800 (1000 at times). Eats the sh_t out of my gas. There are no vac leaks In the past 3 months, I have brought my car to 4 different mechanics and been dealing with a crappy running car and trying to get them to fix this car. It seems most mechanics just tell ya various things, either because they don't want to bother with this car, or they just don't know how to work on the system in this car. I literally get half mpg of what I was getting before I let the mechanics touch my car. In addition, I got many $ figures less in my pocket in the end. It would have been cheaper for me to just drive to you and have you do it all correct! I am exhausted dealing with this (w)re(ck)x. I just need to figure out another solution. The shift light does come on/off. Though, I am not sure if it is working proper. So, I am better off buying a 1.3 carb huh? If this is the case, I will make sure I buy an original 1.3 carb. Thank you much, Mick

Update:
I just took her out for a ride and noticed the shift light only came on when i turned the key on, but stopped coming on while shifting and driving. The other day, the shift light came on regularly during certain RPM's and shifting intervals. Therefore, the shift light does not work properly:) Mick

Edited by mickcrx, 29 June 2012 - 12:55 PM.

[Bubba]

If your shift indicator is not working as it should, I'd lean toward a devac if I were you. I just posted pics of my devac on the devac thread.

I'd start by devacing your current carb and then see how it runs/drives and what kind of mpg you get. You an always get a 1.3 carb later.

But before you rip it apart, check the fuel level in the carb when the car is running (look at the sight glass on the passenger's side of the carb). If the fuel level is higher than dead center, then you might try to just put a new set of float valve o-rings- they can go bad and leave you running rough and rich (and really hurt mpg). It happened to my 87 civic carb.

Edited by Bubba, 01 July 2012 - 06:17 PM.

[mickcrx]

Hello Bubba, I discussed this with my bro, and he and I want to get the best possible mpg, and have decided to just buy a new remanufactured carb instead of rebuilding the one the one that is in the car. We have decided to go with a 1.3 carb for the 1.5 HF motor. We are going to do the devac exactly as you describe in your post and follow your photos, then see how it runs from there. If it is running crappy with new carb installed, I will post pics and see what may be the issue. Maybe I might have to put a differant distributor as you to get the ignition timing correct (hopefully not). The big questions we have before ordering the carb, is: What model or specific carb do we ask for? 1987 HF 1.3 carb (Federal)? This is the plan for me now, but right now, I am having problems locating a 1.3 carb on car-parts.com or any other site. Is your 1.s3 carb HF specific, or is it a carb from just a basic Civic? I looked up your carb model (EA17B) and no luck for me thus far. Check out this carb. It is the only thing I could find
http://www.nationalc...partnum=hon116a

I will call national carb remanufacturers tomorrow and ask if they have what I
need, or if they can rebuild mine and install 1.3 jets and a smaller venturi. Hopefully, I can come to a solution for this car, because i bought it a thousand miles away from home and the seller did not tell me of many hidden issues. I am invested in this car and you are kind enough and knowledgable enough to assist me. You know more than the 4 certified mechanics I brought it to. I want to make the right choices before My bro and invest our time and more money into this project. (Is there anything else you can think of before we move on? My car has a computer under the passenger seat, My car is an original unmolested HF crx, ) I appreciate your help. Sorry to drive you nuts about this car. If you are busy, no worries if you cant reply quickly, I understand. Mickey:)[/background]

Edited by mickcrx, 05 July 2012 - 10:07 PM.

[Bubba]

My carb was off an 87 Civic standard with 1.3 engine and FED emissions. To my knowledge, the only CRX that had a 1.3 liter engine was the 84 CRX 1300.

The pic on the national site looks correct (it has fewer vac fitting along the top as is typical on the 1.3 carb).

You might want check your compression on all cylinders before you buy a carb just to be certain that you don't need some valve work. You can rent/burrow a compression tester from most chain auto parts stores (Autozone/oriley/advance).

[mickcrx]

Thanks Bubba, for your help. The car must run a compression around 180 correct? Ok, here is the scoop. I called two carb rebuild places and only one will put 1.3 jets in my carb if i got the jets. The fellow there, said that it may make my car run too lean and in due time, burn my valves out. I wasn't sure if he truly knew this, or it is something that he was guessing at. You may be more knowledgable on this matter. I figured, if I am putting in a 1.3 carb, it does operate a llittle leaner, but it may be possible to adjust it to run at the level it needs to be (not too lean, not too rich, but on the money to get the mpg as you). Possibly, this is something that can be done? Maybe adjusted using a propane enrichment kit will be the way to go? If all options seem null, I can always just get a rebuilt stock carb, and deal with the wonders of the beautiful vac system. I'm getting somewhere atleast (with the help of you). It is a process, but
I have faith. Thank you much, Mickey & Jeff