27 replies to this topic

[OG Wagon]

Copied below is a mega-PM I just sent out to some individuals that have shown interest in purchasing my carb set-up. I wanted them to be well informed about the carbs, and thought I would post the info. here for others to read/learn as well. As you can see, it was a long process for me to set these up. They can be tough, due to LACK OF PROPER AND EASY TO OBTAIN DOCUMENTATION. Not that everything has to be easy, but if it's possible to make it easy for folks, I figured why not! A few RPR members gave me a lot of help, mainly Airgazm. Below is copies of all I know, and all I got from them. You'll have to apologize, as the post is un-edited, and written towards one-person, not many. But, the info. is still there.


If you have the ability to jet these and tune them correctly, they can be absolutely nasty. Check out what this dude did on his D16. I have heard reports of 140 hp on built D15's running Mikuni/Weber sidedrafts as well, and even higher than that on the D16's. Just to give you an idea of the power potential...

http://www.thezcr.co...ead.php?t=22140

Please understand that these carbs will never be a fix-it-and-forget it carb system. They are finicky, to say the least, and need adjustment frequently, as weather and humidity change. They also need to be adjusted depending on your current altitude. So, the jetting for me in NC (even if I had it right) would more than likely be very different from the jetting you would need up there in NY, for altitude reasons. However, once you get the jetting right, it will probably become MUCH easier. Once the jetting and pilot screws are set, the only thing you would have to adjust at that point would be the throttle screw. On a hot day, the throttle may be a bit high, so you just turn the screw down. On a colder day, it may be a little low, and won't idle, so you just turn the screw up to give it a little more gas feed, and so on.... It's just one screw, and easy enough to do in about 15 seconds or so.

However, as you can see, the work is definitely worth the outcome!

NOW....here are some pics that I just uploaded to my photobucket.

Here is the initial set-up: Mikuni's ran off of the stock fuel-pump








In this set-up, I ran a return line back to the tank, as you can see the lines coming off the fuel pump. There are (3) lines. One is a fuel feed line, one is a line to the carbs, and the smaller line going back to the firewall is a fuel return line. At this point, I also had the gas vent line (for venting gas vapors) was blocked off at the firewall with a vacuum cap.

Continued....due to crappy photos-per-post restrictions.

[OG Wagon]

Next, I decided to go all electric, as the above set-up did not work FOR ME (wagon chassis length probably had a good amount to do with inconsistent fuel pressure that I was getting; prob. wouldn't be as noticable in a hatch or CRX). So, per Airgasms advice, I just pretty much copied his whole set-up. I bought a Carters fuel pump, mounted on the firewall, with an Earl's in-line filter, and Holley FPR and Summit gauge. I tried to get the fuel to push a steady 2.5-3.25 psi, but was unable to get a steady flow. The problem, again, wagon fuel tank was too far back. This set-up worked just fine in Airgasm's hatch and CRXfanatic's CRX, but on mine, the fuel pump was having to work to hard to get fuel from such a large distance. Most electric in-line pumps are PUSH (not pull) pumps, so they push fuel. Thus, they need to be mounted down low, and as close to the tank as possible. If they don't have enough fuel pressure (usually caused by gravity, thus, mounting them down low), then they have no fuel to push. Then, as a safety precaution, they stop working to cool down. This is known as "vapor lock". Fuel pressure then shuts down, and the carbs go to poop. So, this set-up was not working either. I believe that it worked for the other two guys because their fuel tank was closer. So, they had enough pressure coming from the tank in order to make them work, due to the simple fact that their fuel tank was closer to their firewall, unlike my longer wagon, as my tank is father back.

Here's some pics of the car in this state. You can clearly see how this set-up is so desirable. It's really easy to hook up! No need to get under the car, or run lines to the back, etc... However, notice how close the fuel-pump is to the carbs. They give off heat, and heat near a fuel-pump is not good. This alone can cause vapor lock. The fuel-pump can have all of the fuel it needs. However, if it's too close to a heat source, that source can heat it up enough to make it over-heat, and shut off. Also, I TOTALLY don't recommend the Carter pump, just b/c of the HORRIBLE terminal connectors at the bottom of the pump. They slide of VERY easily. And for an engine that vibrates like ours, well, you get the idea....
If you REALLY want a firewall mounted unit, just make sure to get one that has better connectors, something that has wires that are permanently connected to the fuel pump that you can splice in to. Or, just anything better than slide terminals!





BIG EDIT: Be VERY VERY VERY careful about mounting a fuel pump, or a regulator, or anything for that matter, on to our Civic/CRX fire walls. There are several fuel lines that run across the top area of the firewall from the drivers side to the passengers side, basically parallel with where they enter the firewall on the left side. It is VERY easy to nick one of these lines as you are drilling and tapping in screws to mount a fuel pump, etc... If you are going to mount something on the wall, MAKE SURE you know exactly what is behind the area that you are drilling/tapping. Don't ask me how I know. Long story, that involves a lot of gas fumes, fuel soaked carpet, and having to take many hours to pull the dash, patch the line, and put the dash back in. NOT FUN!!!

Soooooo, I then took the car to a shop that had a lift. They tried to mount my Carter push pump underneath the car, near the tank. But, the unit is so large, and there was not a single place to mount that pump under my car by the tank.

To make a long story short, I ended up switching to a very simplistic in-line electric pump that was available at my local auto-zone. It pushed 7 psi, which was perfect, I just used the fuel-pressure regulator to tame it down to the necessary 3.0 psi that these Mikuni's love. The pump was linear in shape/orientation, and fit perfectly where the stock fuel-filter goes under the left rear wheel.

Then, I was running fine. However, it was getting warmer outside, and a funny problem happened. I had capped off that vent line, and was not running a return line. So, gas vapors were building up in my system. They were pushing back through the firewall, and causing fuel to run BACKWARDS through my feed line, and back into the car, fully saturating my passenger floorboard, where the fuel lines run! NOT GOOD!! (Edit: I later discovered that this fuel back-up was a result of a fuel line that I nicked while drilling/tapping screws for the fuel pump on the firewall. See edit notice made a few lines above. But hey, it couldn't hurt to do the mod listed below as well! Getting those fumes out of the vehicle, and down low away from engine heat IS important. Sooooo, read on and do this below as well!)

So, easy solution. Ran a small piece of rubber tubing from the vapor line nipple on the firewall. I ran this down about a foot and a half to near the front sub-frame and steering rack, and just let it hang there, zip-tied to a local part of the chassis. This vents the fuel gasses out of the engine and in to the atmosphere. That helped, but didn't totally fix the problem. I was still getting some fuel backing back into the interior. So, I then drilled to small wholes in my gas cap, and the problem was official solved. Our caps are "vented" caps, but they really don't vent at all! Now, with two small holes, it vents just vine. No more vapor build up, and the car runs strong. That brings me to where I am now. These carbs still need proper jetting for my area, as per my instructions at the beginning of this email. So, you'll have to call Wolf Creek Racing and get the jets from him. He has all of them in stock, and they are very affordable. It just may take a little time to figure out which ones are best. As I stated to you over the phone, the jet chamber is right at the top of the carb, where it says "Mikuni". You just unscrew that one screw on top, lift the cover, and there are your two jet blocks. Each "block" has a top jet and a bottom jet to play around with, and it's very easy to do. I would say that you could change the jets in both carbs in around 10 minutes tops.

Here's some pics of the car in it's current state. Notice the vapor line now going down towards the sub-frame to vent gases. You could leave it open, with no cap, and no fuel line, but you'd be letting fuel vapors escape right near your engine. That's a recipe for combustion! That's why I used the fuel-line to help let them exit safely underneath the car. I have had NO problems with this set-up, and can only assume it is a very safe set-up for the exit of fuel vapors. The vapor line I speak of is located inbetween my fuel pressure regulator and the pressure gauge. You can see it running down towards the firewall.

You may also notice the fuel return line blocked off with a wide screw. Their may be a way to run a return line with these carbs, but I don't currently know of one. Maybe someone else can chime in WITH PICTURES!. This could only be good for the in-line fuel pump. A return line would help it to run cooler and be less-worked, and more consistent. But, with my set-up, it has not proven to be an urgent need.

Also, DON'T BE CONFUSED BY MY PICS: Airgazm and I discovered a weird inconsistenty b/t the wagon and other models. My fuel RETURN line is on the right, and the feed line is on the left. On the hatch and CRX's this is flipped-flopped. But in either case, the fuel FEED line is the BIGGER LINE OF THE TWO. Which makes total since. So, look for your big line: that's your feed line. The smaller line is your fuel-return line, to return unused fuel back to the tank.










You may also notice that I switched from the braided line to the rubber line for the fuel feed line going to the fuel pressure regulator. Back when I was having the gas back-up problems, we assumed it could have been b/c the braided line could not clamp tight-enough around the inlet-nipple with the standard hose clamps I had. So, I switched back to a rubber line there, hoping to get a tighter clamp around that nipple. In retrospec, the main problem was that the gas cap at the fuel tank just needed to have a couple of holes drilled in it. I have not taken the time to switch back to the "pretty-looking" stainless line, but I am sure that I now can with no problems. I still have the SS braided line and the fancy blue/red clamp cover (-AN fitting look-a-like!), and will, of course, ship this with the purchase of the carbs, as well as all of the other fittings and line I have, as I no longer have any need for them.

[OG Wagon]

Parts for Mikuni's: Wolf Creek Racing; 516-635-6775; shop owner: Todd; Todd bought up all of the Mikuni parts and has a fast inventory. He is, overall, a good guy, and a fair person to deal with.

However, when you are talking to Todd, you need to be very concise, and straight to the point. Use no extra language, and have your story totally straight before you call. He has little patience, and has a tendency to SOUND rude, though I still can't tell if he actually is! Maybe he just doesn't care for overly-verbose southern-folks such as myself: fair enough!

Website url: http://www.wolfcreek.../classified.htm

And now, cut and pasted emails that I have been very greatful to have, from Airgazm, and copies from those he recieved from CRXFanatic.

To help answer your questions:

1.) I'm honestly not sure of the size and pitch of the banjo bolts. You should be able to buy all of the PHH parts from ToySport - 1.310.643.6432 or [email protected] . According to my OEM Mikuni PHH Service Manual, the single-inlet fitting is called a FUEL PIPE ASSEMBLY and the part number is N121,017. The BANJO BOLT is part number N101,023. Also, there is a FILTER ASSEMBLY with part number N101,092 located inside the pipe. And make sure a copper crush washer is on the top and bottom of the pipe.


2.) I used a piece of aluminum stock to make my throttle cable bracket. It bolts to another steel bracket that uses two bolts on the head. The other end you see in the picture simply rests on the groove in the valve cover. It flexes a little when revving, but not much. And to mount the cable in the bracket, I just cut a slot in the aluminum and use the nuts on the cable to keep it secure. Here are a few pics from my gallery:










3.) I don't know what thread and pitch the runner fitting is, but I bet you can get a brass barb fitting from a local hardware store. If not, contact TWM Induction and they should be able to help.

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Continued next post...

[OG Wagon]

Hey man,
I was wondering about a few more things, and was hoping you could spread me some knowledge:

(1) I was hoping to just order a throttle adaptor plate, if one was available. I'm not the best a custom fabbing stuff.
Didn't TWM make one, and if they did, do you know if Pierce manifold (or anybody) still sells them? Do you have a
part number by chance? Your manifold is a TWM, correct?

(2) How do I know if I have 40 or 44 PHH carbs? They Ebay seller spoke VERY little English, and did not provide me with any more info. The fuel inlet pipe has two different part numbers, depending on what carb model you have.

(3) Does my STOCK fuel pump provide adequate pressure to run these? I noticed that you have an in-line fuel pump, and was hoping that I could still run the stock one (at-least for a little while, until I could upgrade later on down the road).

(4) Where did you get the blue spark plug wires? Are those a universal wire, or where they made for our cars, and do they come in red? The look killer!

(5) Where did you order your braided lines and fittings? They look very cool, and I would like to order some like them in the near future.

Sorry for the multitude of questions. I just don't know much about these carbs, and am having problems with the search engine providing me with answers.

You set-up is a work of art bro!!

Thanks,
Dan T.


Hello,

I'll try to answer your questions the best I can.

(1) I honestly have no idea if TWM or Pierce made/makes a throttle cable adapter plate for our cars. The steel piece that was on my carbs when I bought them was what seemed to be only part of a plate, and that's why I fabbed up a simple mount from aluminum to hold my cable. The easiest way to make a plate is to use cardboard and tape to make a template. Then once you have a design, bend/drill the aluminum/steel to make a copy. The guy I bought my carbs from, eldo, made his own plate. And to be honest, I've only ever seen custom fabbed plates with this setup on our cars. CRXfanatic may be able to help you. And I don't think my manifold is a real TWM piece because their logo isn't cast on the runner like most. It may be Pierce, but I'm not really sure.

(2) This is another question I really don't know the answer to. The one thing I could think of is using a set of dial calipers or an accurate ruler to measure the inlets/outlets.

(3) I'm fairly sure I remember seeing other members with dual carbs, bigger single carbs and ITB's use the OEM fuel pump. I think it has its limits, but should work for the time being. I was told to keep my fuel pressure between 2.5-3.0 lbs., so that's why I bought a Carter pump and Holley regulator/gauge.

(4) The spark plug wires I have are made specifically for our cars by Nology. I bought them many, many years ago, but I've seen new sets for sale on eBay. They cost about $170-180, and Nology may still make them, but I'm not sure. They were available in red years ago.

(5) I bought all of my -6 AN fittings and line from a local shop, SlowBoy Racing. But you can get everything from places like Summit Racing, Jeg's, etc.


I was exactly the same way when I bought my carbs, and learned most of what I know from the guy I bought them from and other RPR members. eldo, CRX fanatic and fhrcng helped me tremendously.


Here is a PM from fhrcng I received a few years ago:

"Okay here you go....

Main fuel jets: 135
Main air jets: 200
Pilot jets: 57.5
Pump rod setting: 2nd hole
Distributor advance@ idle 14*
Distibutor advance@ full throttle 33*
Regulated Fuel pressure: 2.5-3.0 lbs. Dont have a regulator?...get one.
Cagle makes an easy to use one that is cheap. Also if you are running a return line back to the tank (and you should) put a restriction in the hose after the carbs. You can use an old carb jet for this."


And here is a PM from eldo:

"Everyone i talked to said the Mikunis need the same fuel requirements as the Webbers if not less fuel pressure.(consistent fuel volume is the key to really fine tuning them)A lot of guys i talked to or read about says the stock ignition is plenty good enough for any motor,period.(meaning,not a neccesity ) .The only time you need ignition upgrades is if you have high enough compression where you need race fuel,if your using nitrous(higher compression),or if you have forced induction(higher compression again),or if you are reving past 7000 rpm(couple of racers here rev to 7500 consistently on the stock ign.).You're MSD and blaster coil is good for anything you throw at it.High output ignition systems won't make a motor run leaner,only make the combustion more efficient (burns the fuel there is more completely).
I spent months on the net looking specifically for Mikuni info and most of the stuff i get refers first to the webber then the mikunis(all the tuning methods are the same for both carbs)."

"I ran the stock fuel pump with the regulator set at wide open.The stock fuel pump regulates itself(mine ran steady at 2.7 psi at idle or wide open throttle.Knowing that,i could have taken the holley regulator off and just run the stock setup(i think the Mikunis only need 2.5-4.0 psi).In my paper work,i have the specific reg and pump that is recommended as the best for these sidedraft carbs(more so for racing-consistency in fuel delivery to win races by hundreth of a second.-not required for street use)But if you want to drive with the equipment best suited for those carbs,then use the Carter Rotary Pump-gives 60-70 gph but at only 4psi-perfect because you are not suppose to run a regulator with this pump-says a reg only inhibutes the fuel flow.Check out this web site:

http://www.racetep.c...k.html#webfuel"


And here's a PM from CRX fanatic:

"Jetting:
main air 170
bleed pipe t
jet block 8
main fuel 145
pilot 57.5
pump nozzle 35
starter jet 130
pilot screw 1.5 turns out from seat"



Thanks again!




------------------------------------------------------------------------

Notice the timing changes unnecessary to run these carbs. Have someone adjust your timing following install to around 14-16 advanced at idle, and 32-34 at wide open throttle. These will help them to run at their optimum.

A throttle cable-bracket needs to be fabbed up to run this set-up. This was a big pain in the rear for me. I had an in-law do it for me. He made a GREAT bracket. IT WILL BE INCLUDED WITH THE SALE!!! So, one of the biggest hurdles will already be handled for you.

Whoever purchases these, I will be there to help them with whatever I can. I will not be unsupportive.

If you have any more questions, please don't hesistate to call or email or pm.

Thanks so much guys for showing interest!

[OG Wagon]

Final note,

TUNING/SYNCING Mikuni Carbs:

As I understand it, Weber carbs MAY have vacuum ports for each individual throttle body. A device known as a "minometer" can be used to sync these carbs by adjusting the pilot screw on each runner to match the same on the minometer. However, Mikuni's DO NOT have a vaccuum hook up source for each runner, making them impossible to tune with a standard minometer.

Todd at Wolf Creek Racing has told me that the best way HE tunes them is by ear, with the use of a small length of hose. He holds the hose up to each runner (take off the air filter), and puts the other end of the hose up to his ear. He is listening for the PITCH (think music, like E-flat, C-sharp etc...) of each runner, and he then adjusts the pilot screw on each runner to make this pitch uniform across all four throttle bodies. Their may be another device that can do this, for those less musically-inclined, lol! If you know of one, please chime in.

Another interesting note that Todd said was important during the tuning process: DISCONNECT THE THROTTLE CABLE. Apparently, it puts an ever so slight pull on the throttle arm, which hinders in accurate tuning. So, disconnect the throttle cable, and then reconnect it after tuning is finished.

[OG Wagon]

I hope that RPR members can find the above resource, and any additions that may follow to be of use when doing this great swap. These carbs are hard to come by nowadays, which explains the lack of documentation. I got the impression that most of the peeps who run these are ol' school hot-rod junkies, and these carbs (and carbs in-general) are nearly second-nature to them.

For the twenty-somethings like myself, who are used to EFI, these carbs are a whole new beast. However, I can assure everyone that they are actually pretty cool and a lot of fun. They also sound AWESOME! Most folks thought my wagon sounded like an old-school hot rod, not an annoying, winy, Honda. And somehow, rumor got around that Mr. Taylor's wagon was supercharged at the school where I work at. I guess the high schoolers liked what they heard! They asked me about it, and I just told them "yeah, it's pretty crazy". Why give away my secret!

I will do my best to make a trace a copy of my throttle cable adaptor plate. This will make this swap easier for everyone. I'll post a .jpeg copy of it in this thread at some point soon.

[OG Wagon]

Link to a service manual:

http://forums.hybrid...ad.php?p=771032

I have a link to another site that has it open, no register needed. I'll see if I can find it.

[NWClassicHonda]

Wow, great info and and a very good thread. Keep up the good work.

[rwdcrx]

Wow, great info and and a very good thread. Keep up the good work.

+1...the only problem is that there are only 5 other people on earth that have this set-up. Nice details. I like it, I wish someone would do a thread this detailed for bike carbs.

[CRXfanatic]

Good stuff, thanks for the post...

This came with my carbs... Didn't see it above...

[OG Wagon]

Great addition CRXFanatic. You had been kind enough to post it up before. I am sorry that I forgot to include it.

Man, now that I'm reading this now, I TOTALLY understand all of this stuff. I wish I had understood it more earlier.

Particularly, I now realize that I never pluged up my hose barb. I had it running to the PCV valve I believe. So, I ran two vacuums on the manifold. One to that, and the other to the brake booster. I bet that extra vacuum effected my tuning greatly. Oh well...

[jameson]

one thing i must say, great post guys and this will help me tremendously thanks

[Infinityzero]

Some extremely useful information going on in this thread, thanks guys, keep it up!


Felt like throwing in a picture of my setup just for fun

[OG Wagon]

Glad this is helping someone! I hope that it continues to help others...

[BuffetLife]

I LIKEY!!!