Zedyone_kenobi

Good Luck with the MOT! Please let us know what its like driving that Z over there. I have spent two weeks over in the mother land for two separate vacations, and both times, I wish I had my WRX or my Datsun there. The roads available are just brilliant!

Installed my 40 DCOE webers on the L24: Engine specifications 2.4 liters original motor/head/cam. Pertronix ignition Pertronix 1.5 Ohm coil MSA 6-2-1 headers adjusted idle mixture screws 1/2 turn out Adjusted all idle speed screws (without actuator rods hooked up) until they were about to uncover the first progression hole I had at my disposal, an wideband O2 gage installed into my header (innovative LM1) and a Air Sychronizer tool with weber air horn adapter (note, air horn adapter not shown) My factory out of the box settings for my 40 DCOE 151's were: 30mm venturi 130 main Fuel Jet 170 Air corrector F11 Emulsion tube 55F9 idle/slow running mixture jet Car would not start at all. It would run off of the gas put out by the accelerator pump, but would not stay running. I kept increasing the air fuel mixture (note NOT touching the idle speed screw at all) until the car would start and stay running. This ended up at 2.0 turns out from fully closed. At this point, you MUST let the car warm up to operating temp. After the car warmed up, I was getting an AFR of 10.1 on the LM1. Too Rich. Mr. Franck's of side draft central's white paper points out we should always aspire to 12.5 with our DCOE's. Well I managed to get it to be there running about 1.5 turns out from full close don the air fuel mixture. Car ran smoother like this as well. Initial drive was very promising. However, the dreaded flat spot did exist in the transition point between my third progression hole and when the main circuit came in. I dove back into the side draft central white paper, and a way of getting the main circuit to come in faster is to reduce the size of the air corrector. You see the air corrector is like a vacuum bleed off. In order for the main circuit to work, you have to get the column of liquid up the emulsion tube and down to the venturi. This is done by way of sensed vacuum from the engine. See 3rd picture on the left. The larger the air corrector the more engine vacuum is bled away and it takes more vacuum to pull the fluid up the emulsion tube chamber. Capillary action only gets you so far, and often the stumbling effect is the engine vacuum is too low to effectively make the transition from progression circuit to main. This should happen at about 1400 rpm according to Mr. Franck. Upon driving around I noticed that my part throttle, 4th gear, low rpm (2000 rpm) steady state cruise I was reading about 15.9:1. This is too lean, BUT I knew that running 130 main jets which are really a bit large for 400 cc of displacement I did not need to richen up the main jet. So instead I put in 160 Air Correctors,down from 170. I touched nothing else, and went for a drive. My flat spot on transition was greatly reduced and even eliminated in 1st gear. But was still present on all other gears. However the lean stumble was smaller and the main recovered quickly. I bet your wondering, Hey Zedyone, what about your floats? Well I am not going to change anything else until I check those. Let me make one thing clear, you should always check your floats BEFORE you do any tuning. The float level can drastically effect how and when your main circuit comes in, as a low float level will increase the distance the fuel has to travel up the emulsion tubes. I purchased the Keith Franck float measurement tool off side draft central webshop. I will be trying to see where I am this week. It would be foolish to spend any more money until I check the float levels. Also, not mentioned here, but I did check the air flow through the carbs for balance with my sync tool pictured above. Right off the bat with the engine warm, they were within 0.5 of each other on the tool. So I left them alone. If I wanted to change that, the only way to make fine tuning adjustments between the carbs is to adjust each idle speed screw located on the side of each carb. I did check balance on both barrels of each weber individually and the flow was identical on all three carbs. Weber does include a way to balance each barrel of one carb individually, but I figure that adjustment is probably to make up for some external imbalance, be it rings, seals, etc. If the butterflies on one carb are open the same, then the air flow should be the same. If they are different, there is an external reason. New webers the air flow should be identical. When I check my floats, I will post pics and report back.

I want to close this thread and end it, as they are installed and running. My review is complete as they are just a joy to own and drive. I can finally rev my car up without any issues whatsoever. The Weber carb is a joy to tune and drive with every thing having immediate and measurable results! I want to start a new thread on tuning, and tracking the results of changes.

Okay 160 air correctors installed and wow what a difference. My low RPM air/fuel ratio while cruising in 4th dropped from 15.8 to 14.1. Still a bit lean but the big story is my flat spot stumble at transition to the mains is 80% gone. Almost impossible to make happen as the main circuit is just right there ready to come in and take over when I need it. I will drive it a few days like this and decide if I want to run a 150 AC. I have no intentions on running a bigger main jet.

Odds are your carbs each have an idle speed screw that adjusts each carb independently of each other. You will need to resync the carbs carefully. Which from the sounds of it you may not know how to do. You need to find an article on setting mikuni carbs up for the first time and do that. It will require patience and a flowmeter.

Just to be sure not to confuse our friend, The US spec is 5 deg BTDC. What is called out in our manuals is 17 deg BDTC for european dizzies. If you look on the side of your dizzy and tell us the number stamped into the housing we could clear that up. But I do not think timing is your issue.

Thank you for making new parts for our cars. Keep it up!

Pick whatever pictures you like... http://www.flickr.com/photos/sdamico/sets/72157605246065883/

Hello from the colonies! Great post and fantastic description of the problem. So you have the car running well, but are not sure why the settings are off. I have been playing chase with my SU's for well over a year, and we should start with the basics. First are you positive you have no vacuum leaks? It sounds like you may have a leak with your idle hunting all over the place. Also, if you need to put that much fuel into the system, it may be getting some extra air in there you may not know about. Second thing I would check since you already ruled out your fuel level, is the needle set at the proper height in the piston. Third, are you getting the fuel pressure required to the SU's. I think it is around 3.5 to 4.1 psi. I would highly recommend you take a trip to the auto parts store and buy a combo vacuum/fuel pressure meter (if you do not already have one). It will come in very handy in diagnosing problems in just these areas. I have to assume you are running a european dizzy, and I thought those were required to run about 17 deg BTDC. You may be able to advance your timing some. By saying you are running 3 screws Hitachi's I am assuming that to mean round tops, and not flat tops. Great move with Ztherapy by the way. Great product. Oh another thing, check to see if the fuel line from the bowls to the carb is not bent excessively. Sometimes in shipment they can get kinked or creased. Keep posting your findings. We will all be very happy to help!

Okay, the silver needle was one I got from Ztherapy. My Ztherapy carbs came with the Gold SM needles. I thought I was running rich 12 pages or so ago, so I asked Ztherapy to send me some OEM needles. The silver ones are what I received. I no longer have an OEM non rebuilt set of SU's to check the needles.

The gold needle is the SM, the silver is the OEM

Frank gave me this idea in another post. A thread dedicated to the before and after shots of our cars. The road to show what we have done since we bought the cars. For some it will be a grave to greatness thread, for others, it will be far less noticeable, but we will all love to see the rejuvenation of our beloved Z cars. Engine before: Engine 4-20-2012: Car before: Car 4-20-2012: with BRE centercaps! It has been a wonderful journey, and as time goes on it will continue to improve. Z's are like cheese, they get better (and more holey, with age)

BRAVO! Just beautiful, these cars need nothing to look right, and you prove that with every picture you post!

Well my thoughts are with you MJr. Nothing prepares you for your dad, mentor and friend passing away. I still really miss him.

That means more than you know coming from you Frank. Thanks very much! I will post more videos of my car once I get the Webers dialed in. Actually, you just gave me an idea for a new thread!! new air correctors have been ordered!! I picked up some 160's, which is a smaller size than my 170s' which should be allow my mains to come in a tad faster.

Thanks hunter, love that blue color on yours!

http://www.flickr.com/photos/sdamico/7101921511/in/set-72157605246065883/?likes_hd=1 hope this works! And this is the old gal at the local Friendswood texas annual car show, where she took 2nd in the pre 1979 import class. Yeah. Lost to a stinking 1954 beetle with about 50k in modifications to it. one ugly beetle. But I did beat a nice turbo 912

I will have to go look. E something. I will find out right after I get my needle photos

Yup, the wideband is spot on the best investment you can make with triples. I have been reading more of Francks info, and I do not think I need to go bigger on my primary jet. I am running a 130 now, and from everything I have seen that is large for 400cc of cylinder. I may have too large of an air corrector which directly effects how much vacuum it takes to move the fuel up the emulsion tube cavity. It is more of a vacuum controlled bleed off. Franck says NEVER use the air corrector to correct the AFR on the top end directly, that is the main fuel jets job. But the air corrector will control when the main circuit comes in.

DOH! I had forgotten. I am so sorry.. Yes, i will get you those ASAP buddy.

LeonV Video is coming Saturday! I have to get my Go Pro working again. After I find it. Where ever it is... I may just use the iphone! Its HD and my go pro is not. Also I am not using the white PTFE tape Leon. I have some aviation yellow pipe thread tape. IT says it is fully compatible with silicones, hydraulics and petroleum products. So I hope I am okay. I have a hard time getting NPT fittings to NOT leak. I only seem to have about a 70% success rate regardless of how hard I torque them. Mike, GREAT thread, and my pooling is very minor right now. Almost a non issue. But I have the air horns that slide all the way into and around the venturi (or is it the choke). I have the 151's DCOE I am pretty sure I need to up my main jet. I was reading Mr Franks paper and at low rpm (2000 rpm) in 4th gear holding the throttle steady my AFR were right at 14. He recommends 12.5, and I tend to agree with him on that. I am currently running a 130 main and 170 air corrector. My overall driving is darn near flawless. I do have a hint of a hesitation on the progression around 1800 rpm, but I mean it is slight, and not consistent. I think I am only a few jets and a few twists of the screws to have a perfectly fine running set of webers. Really the more I read, the more I think the hesitation issue in mid rpm thing is blown out of proportion. It seems a perfectly logical thing to tune out. My car was darn near running perfectly 30 minutes from first starting it. The Webers are do darn Logical. I absolutely LOVE them. Before I mess with jets though, I am going to verify fuel level of the floats. Not sure if I am going to do it the weber way, or the Mr. Frank way. I do not know where to get a piece of acrylic that small.

Loving the engine bay shots!!!

I love these carbs!!!!

That occurred to me Doradox, and your right, I would not come off 14 Deg BTDC. I plan to run about 17 on the new motor with a re curved dizzy or a mallory. I just need to figure out the jetting now. I am still getting a lean stumble when I jab the throttle as fast as I can at low rpm. This is normal for the most part as the intake velocity is not optimum, but I have not done any pulls while monitoring the wide band yet. I am just do thrilled to have a car that is happy to rev and drive and sound so amazing. The midrange is a definite improvement over the SU's. It feels very strong! I am still playing with the linkage and spring tension to get it where I like it. It is all about angles! I still get a bit of pooling on my heat shield, but I think that only happens when I slam open the throttles and the engine falls flat. I mean it makes sense. I am dumping gas into the main circuit via the accelerator pump while the intake velocity drops to nil. Where else is the gas going to go but out of the carb?

Nah, Bruce has done enough good for enough guys on this board that he owes me nothing. I asked him to do the impossible. When I sent my SU's to him, I asked him to solve a problem with my carbs when they are mounted to a different intake and engine. That is a tough call. No telling what it could have been. But I still think Bruce and Steve at Ztherapy are top notch guys and would stand behind their product 100% of the time. Maybe it was my intake. Now I am left with tuning a set of Webers and I could not be happier. I drove them to work this morning, and they ran great! I still cannot just jab the throttle as fast as my foot can go, as the suck air, but I can tune around all of that. This problem is solved, but not knowing exactly what it was with the SU's bugs me. I will just drain the SU's and wrap them in plastic, and put them in a box. SHame as they are so darn beautiful.