LeonV

Sweet S2000 Phil! I like the Silver/Red combo. Sounds like some grand plans in the works, good luck!

Ah, that's right! It was Bill that said he exclusively tracks his Z. Ooops!

I'll report back with my findings once I get things dialed in. You can see first hand whether it's worth it or not!

I definitely agree with the rich-running sentiments. Getting a carb to run an engine is one thing, getting it optimized is the challenge. You're definitely on the idles at low-speed cruise and I remember Keith saying that you're about 50/50 on the idles and mains at high-speed cruise, say 75mph. Mine came out running a lot better than it was but there is definitely work to be done! I'll be getting some 110 mains and a set of internal throttle return springs (mine are dead) soon. Keith's Elan (400cc cylinders, 30mm chokes, same as my Z) runs the O3 tubes and only needs 110 mains. Besides Rob, my Z hasn't seen a track yet. My goal is for someone else to be able to drive the car and not tell it's carburetted. Your Z is almost exclusively a track car, so as long as tip-in and WOT are set, you're ready to roll! Of course getting better mpg on the way to the track is always a good thing as well. I need to get my Z out there with you guys.

Thanks for the reminder!

Oh man, this discussion could go on for a loooong time! A good start would probably be buying Obert's book. But to sum it up, of course there is the precautionary warning of making sure all other systems on the car are functional, ignition, charging, etc. A dysfunctional engine will make it impossible to tune and will frustrate you to no end. Once you're ready to tackle the carbs, the fuel levels must be set accordingly. Keith has found that to be 2mm below the brim of the passageway to the aux venturi. Then make sure your carbs are in order: no leaks, barrels flow equally, throttle returns correctly, linkage set up properly. Once that is set, you're ready to "tune". Ensure throttles are positioned correctly to the progression holes, sync at idle and high rpm, play with the jetting... Keith is working on a paper to detail all of this, hopefully he'll have it up soon. We had some very interesting discussions on the physics of what is really going on inside those carbs, and I'm sure he will be covering that in the paper as well. As far as venturi-to-engine size question, that is a good one and not simple to answer. Venturi size would be best determined empirically. The goal would be to go as big as you can without sacrificing driveability, and this depends on parts availability and the skill (moreso patience) of the tuner. Intake length sizing is its own discussion, and I've made some fairly detailed posts on it on HybridZ. In a nutshell: Use air horns, or at least have some sort of radiused opening at the inlet of the carb Longer intake valve-to-carb inlet length is more efficient at lower rpm Shorter intake valve-to-carb inlet length is more efficient at higher rpm Have as few bends as possible and try to make it a straight shot into the cylinder I've designed a spreadsheet that is supposed to predict intake and exhaust lengths according to RPM but I've yet to test it. I'm sure Obert's book has the details on it. Internal Combustion Engine Fundamentals by Heywood has some very good sections on intake and exhaust design. I've recently bought Obert's book, and in some respects it's outdated (which makes it cheap ), but most if not all of the information will be very relevant to the L-series engine.

My setup: L24/E88 with stock cam 40DCOE18 Webers with 30mm chokes Nissan Motorsport header with dual 2" pipes all the way back Started with: 50F9 idle jets (too rich) F11 e-tube (junk) 170 air corrector 125 mains (bit rich) *** I need to track down accel pump specs Performance resulted in really soggy idle and cruise mixture and some bogging on aggressive tip in at lower rpm. WOT above 3500rpm was good, no matter the gear or how aggressive I was with the throttle. After tuning day: H223 hypojets (.022" orifice, 3rd air hole) O3 e-tube Custom air corrector for O3 tube 125 mains Idle is way better, less soggy but no flat spot. Cruise mixture is better but still rich. I plan on going to a smaller hole on the hypojets, which would enrich the idle but lean out cruise. I think the H222 or H221 setting will get me close but we'll wait and see. At WOT, my mixture still tends to go richer as rpms climb. I'll talk to Keith and see what he thinks. I'm thinking this may require a different e-tube, perhaps an O2, as it has less holes to lift the fuel up. However, low and midrange is fantastic. The mixture is spot on with much less jumping around as shown by my wideband. I still have an initial hesitation issue when quickly going WOT. It'll hesitate and then pick up, so this points to an accel pump issue. I need to investigate this further, as I don't know how much bleed-back I have and don't remember the size of my pump jet (40 or 45 I think). One other thing I discovered a few days ago is that my internal return springs need replacement. I was doing idle-sync and decided to see how well each carb returns. After disconnecting the linkage, I blipped each carb independently to see if it had the same airflow before and after. Each carb was flowing more after I blipped the throttle, indicating that it is not fully returning. Pierce Manifolds has the right ones for a good price.

FWIW, Bryan Blake goes by "1 fast Z" on hybridz.

Man, what an awesome day! Throttle response has never been so crisp before and the idle is so much cleaner. I love how my mixture got steadier too. This is just the beginning, I'll be playing with the hypojets to find the optimal ones as well as increasing my pump shot and possibly upsizing the chokes. Achieving Weber nirvana is a (big) step closer! Big thanks to Rob for setting this up, Keith for the time, parts and knowledge, Original Customs for hosting, and Glenn, Patricia and Bill for coming. It was a blast!

Heck yeah I'm still in! About to print directions actually.

Carefully apply heat with a heat gun and see if it loosens up. Don't melt anything.

Download the FSM from the "Reference" section of xenons30.com, everything you need is in there. The Haynes book is woefully underwhelming.

You can always leave it as is and hope for the best! The way I justified it to myself is that the engine spins counter-clockwise when looking at it from the driver's seat, thus the header will move away from the floor under torque. The only time I can hear my header tap is during a bumpy, hard right corner and I attribute it to poorly-done exhaust hangers.

Ah, the machine shop ground the washers. Shims would be a different issue altogether! I can see your concern, although I'm not at all worried about my floor (more about the header, really) if contact is made. Since you don't want to clearance the floor and don't want it to have a chance at tapping it, bending the pipes would be your best solution unless you want to put a dent in the header where it is closest to the floor (I wouldn't). Wrapping the area may help with heat, but it also expands the effective diameter of the piping, meaning that the wrap will be even closer to contacting your floor.

You're going to have that problem on pretty much any long-primary header in an S30 (Stahl, Nissan Motorsports). As long as all of your mounts are good (engine, trans, etc.) and the exhaust is mounted properly, the header should not contact the floor. You might get some taps now and then, and even then only when driving hard. That's based off of my experience with the Nissan Motorsports header. As far as "cooking' the floor, will you be tracking it? Otherwise, I wouldn't give it a second thought. The easy way to go about getting good clamping on differing flange thicknesses (this will happen with any header) is to grind down the thick washers at the shared studs so that they become stepped, in order to accompany both thicknesses.

Making great progress! Keep up the hard work, Tom!

Not a problem. Enjoy!

You should be able to see it by employing some optical trickery. If you don't have a small mirror handy, grab your wife's/girlfriend's make-up mirror. You'll have to be discrete. This tool comes in handy sometimes: http://www.northernautotools.com/specialty-tools/engine/fan-clutch/performance-tool-w1259-telescoping-mirror-large.html

Regarding where to find the cam mark, here is a perfect example from Blue's Tech Tips: http://atlanticz.ca/zclub/techtips/cam/index.htm

Valve lash is the same. Sounds like someone put in a 260Z longblock and attached the '72 carbs to it. There's a very good chance that if the back of your cam is stamped with a "C" it is a 260Z E88 head. If that is the case, go off of 260Z timing specs. The reason for this being that the combustion chamber shape and cam profile slightly differs from the L24 and thus needs a different advance curve. Since the 260Z head is open-chambered, I would expect it to require a bit more advance than a '72 L24.

I'm not sure if you've read the contents of this thread?

Wherever the certain measurement is spec'd from. I would think from bottom to cam tower mating surface, or to valve cover mating surface. I haven't checked myself. Looks like stock height is around 4.25".

Sounds like the filter is overly restrictive, at least moreso than the regulator was.

Go to a machine shop and have them cut some shims out of spring steel. McmasterCarr has shim stock if the machine shop doesn't. Measure the thickness of the head to find out how much was milled, the stock numbers are somewhere on the interwebs.

Technically speaking, flow is what matters. It doesn't matter if you have 0.5psi or 3.5psi, as long as enough fuel gets in the bowls. Don't worry about pressure (unless you have zero), just drive the car and see what happens. Uphill highway pulls will probably be the most revealing test of whether you're getting enough fuel or not.