Chino 240Z

Hey 240ZX, I could sit and look at the motor all night long! Your Z is my Zs hero! I need to show Mrs. Chino what we want Santa to do to ours!

Gosh, you're close but like me want next to perfect. Kinda a process of elimination by rechecking or readjusting each 1 or 2 more times to dial them in. 1.) May have some air leaking around the shafts? 2.) Beandips info on the butterfly adjustment is a good place to check. 3.) I would get that 20wt. oil replaced with ATF or Marvelous Mystry Oil, closer to 5 wt. 4.) Float may need 2-hairs of adjustment more then fine tune with mixing nut. 5.) I set each needle to its own nozzle and carb, not one needle to the other needles set point. No 2 carbs are exactly the same. Try this: Mixing nut / nozzle all the way up then with the needle pulled out or left out a tad long and needle screw loose enough for needle to slide, gently set the piston in it's carb and softly push down till needle touches nozzle and "soft-clunk" the needle pushes up and into the perfect position. Then gently lift out piston(try not to move needle)and tighten the needle screw at that postion. This way you know each needle is closed and at the bottom of its own nozzle and when shut, it's shut. Each needle will be equal to each other and with in its own nozzle & carb. Now open up mixing nut to desired starting point and tune. 6.) If you didn't use new gaskets between carb & intake you may have leak there? Good luck.

Stay organized and neat in disassembly. Layout some towels to place your parts in order. Clean with carb spray and an old tooth brush. Becareful with the pistons with the needles in them, don't let them roll off the table, drop them, or you may bend them. One at a time is good advice first time into them. The Video should get you through them and will educate yourself with what each screw does. You will be surprized how wrong the previous owner of your car had the carbs set up! We still can't figure out how the guy ran our car so well when he had it? Leaking shafts, floats out of whack, no air tubes, no pistion oil, homemade air cleaner, 5+ lbs. of fuel pressure and this thing kicked-A, purred like a kitten at idle, and won races! I can't believe it! Some shade tree mechanics have all the luck, I gotta fail a few times before I get things right! Good Luck ChinoLOL

Tune up, tune up, tune up. But also make note of when the backfiring is happening, on the gas? off the gas? idle? Out the back? Up under the hood? The carbs can backfire out the carbs in a lean condition, and from inside the car can sometimes seem like it's out back. Exhaust systems shouldn't be causing the problem, but some performance exhaust systems can sure amplify a problem to make it more noticeable. Do what basic tuneups you can do, a little investigative research in your problem and these guys here will help you get down the right road! Cheers Craig

Hi Dan, Chokes in California may help on cold mornings to get the idle up a tad to help warm up the engine, after which you would push in the cable or turn off the choke. Now I don't get the chance the run my car often only when getting ready to go to the track and it starts, bang everytime, but we'll see this winter? No choke cables here either and the linkage on the carbs are left alone intack. I have to stop and think, but the cables are attached to the fuel nozzles under each carb. In cold areas a fuel rich car will start better with alittle extra fuel and warm up with a higher idle quicker. When you pull the cable it pulls down the nozzles a tiny bit,this allows a little more fuel to be drawn up from the nozzle in the bottom of your carb. Kinda like temporarily raises the fuel level and riching up the fuel for cold starts. When you push the cable in the spring on the nozzle returns the nozzle back to the normal position. Just like when you turn the mixture nuts on the nozzles, turn up leans, turn down richens, choke on pulls nozzle down to richin. I think if you leave the choke turn on you would be running rich and using more fuel, probably not running good either. But not having the choke cables won't hurt things. It is nice to keep parts on the car if you want to keep it's value and at stock condition. I like that idea of keeping anything you take off or don't want to run with, incase you sell the car. But for racing or just goofing around with, if it don't need it? I take it off.

What he said. Chokes may be pulled on alittle, choke linkage to the nozzles under the carb my need some tweaking, they may be binding and causing the nozzles to be in a choke position. With the oil dash pot rods tight (or what ever we call em) and about 2 to 3cc's of oil, the pistons are suppose to feel sluggish to push up and will drop slowly. This is the oil working in the cylinders squeezing by the brass bulb in the cylinder giving the piston a soften or dampened rise and fall with more or less throttle. Sounds like they are working right. Do you know which screw is your idle screw? tight close to the carb, one on each carb. They will be the ones that will open the butterfly in each carb. The car should idle with the butterflies open just a crack, to much will allow to much air flow and will give high idle. These screws only work when it is idling. When you push the throttle the linkage begins to open the butterflies the rest of the way. A uni-syn flow meter is used to measure the air flow of the 2 carbs to help match one with the other. You can survive without one, but for 25 to 30 dollars they are great! You will try to get the opening of both butterflies about the same for a smooth idle, but that doesn't mean they will both be set "exactly" the same amount for best results, one may be a tad more than the other. Once the idle is okay, you can begin with adjusting the mixture nut under the carbs. Start 2.5 to 3 turns open, adjust up or down small, equal increments at a time until you get the quickest idle before it starts to rough up the idle. Too high will make a lean condition and too low will give a rich condition, you need to play with it for the best result, and again may need to close or open the butterflies a tad with the idle screws you were adjusting earlier, kinda back and forth till you feel it is at its best. After a couple iterations back and forth it should be at a smooth and low idle. Final idle is about 800 to 1000 RPM's. Here is a easy mixture test: On the underside of each carb you will see a small lifting pin with a spring on it. You will notice that if you push it up and down with your finger the piston will rise up as you push and drop down as you release your finger. With car warmed and running, carbs adjusted the best to your ability, push the lifting pin up about 1/16" or more: *PRM's rise and stay up, that carb is rich. *RPM's rise briefly, then drop, mix is about right. *RPM's fall, engine get rougher, mix is lean. It's gona take several readings, some looking at the carbs to find what moves what, and several attempts to get it, until you get the hang of it. Now Go For IT!

Everything will be just fine cranking it over in sort 30 to 40 second intervals while the gas is working its way up from the tank. Holding the key over for long duration is only going to heat up the starter and add wear. If it isn't getting fuel to the carbs then you need to stop, back up a second and investigate from the pump back to the tank. If you must prime the carbs, a little fuel down the vent might do the trick, but too much is the same thing as too high of fuel level in the bowl and here begins flooding the carbs (the dribble out the carb syndrome) gassing up the cylinders spark plugs, then its gotta be wide open throttle, crank, crank, crank to air it out. Maybe by then you have just drained the bowls to the right level and the gas has made it up from the tank and your back to square 1 and ready to go. If you need to get inside the valve cover for something else besides to manually pump the gas pump, maybe check valve cleareance, timing chain wear & tension, spings, dirt, then great, you might want to have a new cover gasket to put on incase the old one sticks, splits, and desides to give you a leak, don't forget to check what the torque is on the bolts when you put the freshly cleaned cover back on. (I need to bring out the manual at this point, I don't remember certain things any more either from the gas fumes of the flooded carbs or from partying like a rock star years ago. . .) If you are like me I just want to get the dang thing some fuel, sit in the drivers seat,crank the key get it running enough to jump out quickly grab the throttle linkage and keep her going while I make some adjustments to smooth her out. Let her warm up, idle a bit and then listen to what she is telling you she needs. I hate it when ya open a can of worms compounding one problem with another. I have to remind myself "K.I.S.S." (Keep It Simple Stupid) That's me! Good Luck.

Hi there, Victor is right, it should fuel up to the bowls in a few short cranks, after that, you might open the bowls and have a peek. You can verify you are pumping gas from removing a fuel line feeding the carbs and having someone crank it while you hold a glass jar, not plastics- gas may eat it up, you can see the volume of fuel in a couple of seconds, it don't take much to fill a bowl. Victor has the starting list of investigations, you'll want to check and double check things one at a time. Read up on a couple of previous threads hear in the SU carb. department and see how several of us have gone thru the same thing. We gotta kinda eliminate alot of misc. possiblities that can come up with a car if it has been sitting for a while, ya know. But give it a go, and people here will follow up on you and will have some ideas to offer. :classic:

Right on Seerex! Sometimes you can only use a used part for so long and then ya have to go new! I milk my parts till they are dead. I get mad at myself sometimes when I knew I should have gone new and saved time. So some rebuild kits or gas valve jets are on the list huh. I haven't seen the Monza exhaust, but the MSA one seems like the one I would look into. 3 to 2 then out the back with a nice straight high flow muffer would do the trick. Expect some noise from it all, I mean a good noise if you like to be heard, I know I do! I don't know if any of the headers are ceramic coated but if you can swing it I would do it. I have a 93 Firebird with coated Hookers under the cramped hood and it drops the heat dramatically under the hood. The coating will also save them from rotting out too. There are several companys that offer it, but you mainly want it inside and out. Well, sounds like you getting all together! Good Luck Craig

Does SCCA require you to latch the hood all the way? I run mine popped open with the hood-catch holding. NASA told us it had to be shut all the way unless it had a safety lease or cable, but the OpenTrackRacing guys say no problem if I think it is safe. Never have the catch release, but I have been playing with some cable & pins thinking of making a secondary catch. I like to think that running with it popped open helps vent the heat? What is your take on this? Thanks, Craig.

I was hoping to read you were laying rubber and had it running! Well, next time. I don't know about the rebuild kits. I agree about the 125, compared to 18 to 30 frog skins. I guess the more affordable ones work or else they wouldn't sell them. The ZT kits come with 2 hour SU video tapes and maybe a little better product too. I would still scratch up to cash for the tapes even if you buy different kits. I had just ordered a hand full of float bowl gaskets and intake gaskets for the tool box. You're not the only one trying to get the fuel level right. I've wrinkled the gaskets enough and now they need replacing. Tomarrow I think we're going to put on the exhaust silencer, run the car around the block a few times and see if the float levels and fuel pressure setting changes are better? Well here's to ya, Cheers! Craig:pirate:

Tom? Is that you from RRR forum? If so are you still involved with fast electrics? I haven't floated my boats since last year. When I got back into the Z thing I haven't had time for them and they are behind glass cases. Good to see ya with a Z. If those are original springs, they may be getting tired. Reminds me of our old 67 & 68 Mustangs, they had springs that softened in time. So if ya don't mind the bumps look into a set of springs & shocks and get that Z LOW. I once had a 72 Z that I put some rubber spacers in the springs to level the ride until I could afford a new setup. Take it easy and I think I look up the RRR site again, haven't been there for awhile. Later Craig

Hmmm, sounds like the front one is working right but the rear bowl is overfilling because your gross fuel jet or valve won't shut the gas off when the float comes up to level. Are you sure the float is not leaking. There may be a piece of debris in the valve which means you'll have to carefully remove the float by sliding its pin out, then with a open-end wrench remove the brass valve, you can remove it with fingers once you get it loose. Careful not to slip with the wrench and break off one of the tabs that hold the float. You can disassemble the valve by carefully removing the retaining clip and pull the needle and spring out of it for inspection. Some valves are like a roller ball, some have a brass tip and some have a rubber point tip. They do wear our and need to be replaced, call ZTherapy, Victoria British, MSA ... about 23 to 30 dollars? Sometimes the dirt falls out while you are taking it apart and you'll never see it. I was talking to Steve @ ZTherapy tonight and he reminded me that the floats are easily swamped or flooded by to much fuel pressure, even if you have them set at the right 9/16" level, which is my problem to high of pressure from elect. pump & fuel reg. set to high. Ultimately you will try to match the front bowl level and rear bowl level when they are both working properly. Well looks like you made ground, but that rear bowl filling to high is the shut off valve or float not pushing the shut off valve straight or properly, or to high pressure, or float is not swinging freely and is sticking, or has a hole in it. Keep looking. Craig

Did you compare the base diameter of the old & new needles? Some where in the past 30 years the pistons may have seen some activity to damage the holes so good needles will not secure right. ZT has refurbished matched domes & pistons. Have you tried rusted-nut-buster spray, or maybe heating up the area around the broken needle to loosen the fit. Don't know if the metal would expand enough to let go? They freeze motor parts or sleeves and what not to before pressing together, so. . . aaaa I don't know. Well I guess reach for your oriental friend- Mr. Wallet-San.

I know what you mean, sometimes you stand to close to the forest to see the trees, or something like that! Well consider the things you have already paid for a needed tune-up and once you have it running it will be even sweeter. Hang in there not only are you trying to fix a car but you are also teaching and learning as you go and that is worth the effort. Last week at the track I wasn't happy with the results of the $1000 I poured in the carbs, ram tubes, filters, gas, travel, time and was about to put the old stuff back on but decided to stick it out and keep trying things. I didn't get to where I wanted but came home knowing alot more and alot closer to my goal. I'll get it yet and hope to pass this stuff on to others as they have to me. The 2 fuel bowl vent lines just go to a plastic fumes box that is stuffed under the fender. I don't have a stock filter where they would normally take the fumes to be recycled. There is a thread somewhere around here talking about this recently. Anyways heres a picture of the box. Also you may need to lower the gas level just a little bit more with the floats, and start with about 2 turns open (or down) with the nozzel jets under the carbs, and just crack open the butterflys with their screws (just so the screw starts to move them) to get it to idle when it does fire. You still have a fuel level on the high side (I think) that's why fuel is being drawn out of the nozzles in the bottom of the carbs so easily. Go to ZTherapy.com and look around they have some pics that may help identify some things. Gambate Kudasai! Hang it there! Craig :ninja:

When I had a parts car in my deal, the parts car was more in the way than anything I could use, so I took the items I "might" use and stuffed them in storage then got rid of the parts car. Try and see your deal without the parts car, is it worth it? Does the good car depend on having a parts car to keep it going? I consider a parts car just icing on the cake for me, and a relief for the other owner to get rid of - if ya know what I mean? :nervous:

You're saying that when you loosen the screw on the side of the piston the needle won't fall or pull out? And when you insert a new needle into the bottom of a piston and tighten the holding screw the needle is still loose?

- or a bad coil, do you have 12V at the coil with the ign. key on? Double check your fuse panel too. Make sure you are grounding the spark plug on some unpainted metal, I prefer using a corner of the eng. block or somewhere you know it has a good ground to the batt. ground. Bad or weak batt. with dirty terminals and a poor ground at the spark plug may give you a false spark check too. Also if you pulled any wiring off from the items you were working on you might double check they are tight & back to original terminal. I once mixed up one wire from the pos. term. of the coil to the neg. term. and chased the mistake all night untill I convinced myself to double check what I had just finished hooking up! :stupid: Keep Looking.

I'm not sure the gas is still good after sitting for 2 years in the tank? But if it ran on starting fluid it is a good sign that it will turn over. Besure to dump all the fluids and start fresh. Clean your plugs and anything else just so it will help it fire up when you go a cranking on it, hopefully it won't grind for to long. I do know, but if you have had fuel pouring out of carbs, the cylinders are probably to gas wet to fire. Also a fresh or full charged battery so you have full voltage for spark and the abuility for the starter to crank without dragging.

Yep, the air velocity tubes or air horns fit just fine. Just putting them on the old SU I had made a big difference, then they went on the ZTherapy carbs when they came. The intake manifolds are E31 and the cross piece is just stock too. All the smog or vac. lines have been removed and plugged. I have seen some nice after market cross pipes that are really clean looking. I'm still dialing in these new SU carbs, driving up the street and back is a way different situation than opening her up on the track full throttle for a long time going thru the gears, I have some more homework of tuning to do. I got back from a trip to WillowSprings and now trying to find time to retune it, but I'll have to put a silencer on the pipe to quiet it down inorder to open it up on a city street or freeway close by. Risky don't need a ticket.

So you got the car running? and you say the pistons don't down back down after you let off the throttle? If you use your finger and the raise and drop and go clunk then they should be okay. Besure that your butterfly valve is closing after you release the throttle. You only want them open a crack for the car the idle. If they are more the idle maybe so great that the vaccum is holding the piston up. Is the engine run fast? or just idling? You can pull off top of piston dome and remove piston, spring, and dome to clean with carb cleaner. Becareful when inserting piston back so you align the needle back into the nozzle hole gently. You don't want to bend it, or a bent needle that rubs the edge of the nozzle will keep the piston from dropping back down. You might want to check this too!

I agree with these checks. Gently remove cover and slowly lift out float. Check for gas in the float, is the float swollen? Should have fairly nice edge not fully rounded or ballooned up. After removing gas jet valve and carefully take apart and check for debris. Put back together and install float back onto cover. With cover upside down and level the float should be gently settled about 9/16" space between float and bottom of cover. Adjust by tweaking little lever that pushes the gas valve closed. Check for junk in bottom of bowl before you reassemble the cover. I think you should solve the gas overflowing problem before you go to the next step and that will be getting into the carb to check and set the main jet needle and nozzel, and to check, clean, and to quick test the piston to be sure it is operating ok and not hanging up. If you tear into the carbs only do one at a time incase you can't remember which part or screw went where. Good Luck

2Many, I understand and agree. I did make up some log sheets and tried to record tire temps, pressure, track temp, notes of adjustments that were made before and after a run. Somewhere this info. compiled will help my setups per track. I am using a Raytech Laser Mini Temp gun, do you know if this will give me the same results? The tires are Toyo RA1 225-50-R14, the max. temp I think I saw was 145* with 125* track temp @ 2:00pm. Another Turbo-240Z that shared our shade had Yokohama (street tread, I think) tires and I read 175* after one of his runs, OUCH-HOT. The next time out is December, Wed. 3rd @ Willow Springs, the big track. The temps will be way down then too, so we are preparing and talking about the things we want to try and how to get better results each time out. I showed my daughter how to help by taking the car & track readings, covering the tires in the direct sun, keeping the fan on the engine, preparing the car before and after a run and stuff like that. It's tuff being a one man show. So we are all learning what and how to do things to make everything go well. Mrs. Chino-240 Cindy can't wait to go out again!

Ya know every time I looked at it I wonder, and now that I was reading the temps across the tire somewhat different, I got that stooper of thought that I might put some positive camber back in. I saw a camber degree little tool angle, thingy in I/O Port, Racers Equip. or some catalog around here some where around here, for quick camber angle checks. I think I'll hunt that thing down. Thanks. I'll think of acouple more things on my mind I'd like to pick your brain for. craig

Thanks 2Many, Still learning what this car is suppose to feel like. I have a mechanic friend with some professional experience with the whole game. He has several cars, one is a 260 & a 510, I will add the camber question to the list I am putting together so I can go over it with him. The tire temp, was about 145* inside edge, 139* in the middle and about 136* on outside edge. All 4 tires had this type of reading. Except the lefts were hotter than the rights because turn 8 & 9 are 90-110mph turns just before you exit the track to the pits, so the holding side (left) builds the heat. Victor, I was out of their way in the turns but always gave them the point- by for them to go ahead and pass me a the straights, yep, they're fast! I was all over the rear of one ZO6 for 2 laps, I was learning the line more by the end of the day. I'm not out of the woods with my nes SU carb problems yet. Over 5000rpms, 5th gear over half throttle would fall, sputter, I am working with either too much or not enough fuel, (on the straights wide open). But it's getting better with each little tweak! Cindy at the wheel in this pic.