cygnusx1

I did the locktite thing on my turbo Z a few years ago. Â Seems to be working. Â When it fails, I'll put in the new crank I have and rebuild the motor. Â Just check the pulley bolt every month or so. Â That's how they fail. Â The bolt loosens and the pulley wobbles the keyway to death. Â By the time you are aware of it, it's too late.

 double post again!....wtf

Oh yeah you are dead on with that guess! Â But like I said, I can roll the throttle on from 10% to WOT in about 3 seconds and the motor takes it like a champ. Â If I do it in 1 second, she bucks a little. Â If I snap it open she bucks for about 2 seconds!

 my pc keeps double posting,,....arghÂ

From about 10% throttle or less.

I tried a ZERO bleed back and it seemed worse. Â It seems the slower I move the throttle plate the better the motor likes everything. Â I think the accell pump is OVER doing it. Â I will confirm/bust this by adding more bleed. Â I am running a 13lb flywheel so the motor responds really quickly. Â Maybe that's why the pump needs to be leaner...? Testing resumes. Â

I finally got a chance to test drive the L28 240Z with the new 32mm chokes in the 40DCOE-151's.  Initially when I upped the chokes from 28 to 32 , there was a tremendous hole in the power from roughly 2000 to 3000 with any load on the motor.  I knew I had to tweak the mains and try to get them to come on sooner.  The first thing I did was to get the fuel level in the bowls dead on.  I measured down from the top and tweaked the floats to get 25mm from the carb body top.  That made a big difference.  The levels were low by 6+mm by just going with the float specs for my plastic floats.  Do not trust the float specs.  Measure the level in the bowls! Next I drilled out the main jets from 125 to 135 and then 150.  I also opened the Air Corrector to 195.  The car was better but still bogged on quick throttle in the 2000-3000 range. Next, I closed off the bleed holes in the accel check valves.  That didn't help and possible made it bog more.  I opened the cover for the Accel pump weights and rememberd that the PO had installed plastic BB's on top of the weights?!?  I have no idea why but I assume he was battling the bogs.  I removed the BB's.  I discovered that one of my Accel Pump check/bleed valves was not checking consistently.  I opened it up and changed the little ball inside the bad valve and re drilled 0.055 bleed holes.  Fixed. Test drive went great.  Plenty of torque, great heel and toe response.  Almost zero back fire on decel from any rpm.  I was still getting a little bog if I slam the throttle open to quickly.  I know this is something that Weber drivers know how to drive around.  Roll the throttle on as the revs climb.  That said, in the interest of driveability, I put the car on a hill and shifted to fourth to get 2000 rpms.  Lugging the motor and making really poor carb conditions with slow air.  I slowly opend the throttle and the motor pulled perfectly smoothly from 2000 and up with the throttle WOT. I repeated the experiment but opened the throttle more quickly, and got a short bog.  I opened it REALLY quickly and got a longer bog.  What does this say?  The accel pumps are causing the bog.  Maybe that's what I WANT to see.  How do you read it? My next step is to put more bleed in the accell circuit. ...oh and no lecture about a WBO2.  I know I need one, but Webers CAN be diagnosed without one.  Â

You know you've spent too much time with DCOE's when, as you drive, you start picturing the accelerator pumps squirting, and you imagine the fuel emulsifying as is comes up through the main jets!     Great stuff.  The designers of this stuff were pure genius.  Even in today's EFI tuning, a lot of the parameters we control are defined by these carbs.  Keep on tuning!

Nice job. Â Two words: Wave Soldering. Â Send that out to a manufacturer and have them marketed. Â I think it would sell if it were priced right.

When you snap the throttle open from low revs and high loads, your vacuum pretty much goes away.  Without vacuum, there is no way for a carb to deliver fuel.  That's the job of the mechanical accelerator pump.  The pump will deliver fuel under the exact conditions that most people observe a flat spot.  There are so many documents out there to tune webers but here is what I have learned from experience and from digesting everything I have ever read. Tuning a DCOE is as follows: KNOW THE BEAST  Write down all the specs of your carbs. Model Choke size Aux venturi Idle Jets Main Jet Emulsion Tube Air Corrector Pump Jet Pump bleed jet FUEL PRESSURE - 3psi  < I filled this one in for you.  Make it that. Needle valves THROTTLE PLATE POSITION  Mechanically establish the throttle plates, all identically, just downstream of the progression ports. You can do this by looking through the progression holes with a light. (future angle adjustments should be limited to +/- 1/4 turn on the stop screws from here on and in the future for idle tuning) WATER IN THE POOL  Float levels (CRITICAL) measure the fuel level in the bowls.  Take out a main jet stack and measure the fuel level.  Should be 25mm from the top of the main jet hole. This affects transition greatly! higher levels = earlier mains. MIXTURE SCREWS?  Turn the idle mixture volume screws out to the spec for your carb model. These screws don't mix fuel and air.  They are controlling how much premix of air fuel is going to the engine at idle. BEST LEAN IDLE  Establish idle speed by iterating adjustments in the following; Mixture screws/+- 1/4 turn on the throttle stop screw/ignition advance-retard. Repeat over and over to get best lean idle (I do it by ear turn each mix screw in SLOWLY until the motor roughens and come back out SMOOTHLY until it smooths out again).  Then turn all the mix screws out(rich) 1/4 turn if you get popping on decel later. (helps reduce lean pop during decel)  Stay within the specified TURNS for your carb.  If you need to open them up too much, you need a larger idle jet.  This is critical to understand because the idle jet is also feeding the non-adjustable PROGRESSION PORTS.  If the idle jets are too small or too large, you will get bad progression off idle. REMEMBER ONLY!!> +- 1/4 turn on the throttle stop screw.  If you can't get it in that range, you have other issues like vacuum leaks and/or too much timing. If your timing is too retarded the motor want to idle slower, forcing you to open the throttle stops.  This exposes the progression ports and renders them useless for progression.  Fell free to use more ignition timing to keep your progression ports COVERED! TEST DRIVING  Establish proper main circuit to get good AFR's and drive-ability from 2500rpm and up. This is where a wideband is priceless.  Experiment with slow throttle movements and focus on steady state and power smoothness above 2700 rpms.    Choke Size x 4 = main jet    main jet + 50 = air corrector    performance engines can have mains and air correctors closer in size.    Generally, use smaller auxilliary venturi with larger chokes.    Main Jet affect mix from about 2500 and up depends on choke size, and air correctors, fuel levels.    Larger Air corrector leans out the mix towards higher revs and can bring the main circuits in sooner.    Emulsion tubes are generally "fuel" curve tweakers. Use them later after everything is working, IF you have too. MECHANICAL FUEL INJECTION  Accelerator Pump tuning.... I really don't have much advice here except that you can adjust the DURATION of the fuel squirt, and the VOLUME of the fuel squirt independently.  These are the variables: pump stroke, jet size, and bleed size. The little jet at the bottom of the bowls is a check valve that feeds the accell circuit called the Accelerator Pump Discharge Valve.  It also has a bleed back hole.  You can change the size of the bleed back hole, and the pump jets.  Generally leave the pump stroke alone.  SMALLER bleed back hole and LARGER pump jet will make more fuel go to the engine.  Add the two hole sizes together to find your DURATION index. (I invented this. It could be trash theory If the sum of the two is large, duration SHORTENS, if the sum is smaller, duration LENGTHENS. The bleed hole size mainly determines the sensitivity to throttle position changes.  Example: A large bleed back will squirt very little fuel to the accel jet, during slow throttle movements.  When moving the throttle slowly, the fuel will simply bleed back into the bowl instead of going to the engine.        ANALOGY:  Fill a cup with water, drill two holes in the bottom sides.  One hole feed the engine and the other hole drips back into the sink.  Those are your variable.  Size of the cup, and sizes of the holes. OK I am sure I missed stuff and there is more to it than that but it's my mental digest.  I didn't talk about synchronizing because that is not really a carburetor tuning thing.  It's more of "put on clean underwear thing." I am in process of tuning my carbs now.  I am also battling a progression stumble since increasing the choke sizes.  It's all about slow air.  A carburetors WORST enemy.

Nice. Â I have DCOE40's on my 2.8 and just took the 28mm chokes out, and put in 32's also. Â What jetting and aux choke did you end up with? Â Most video cameras are very sensitive in the frequency of L valve noise and makes them sound like crap. Â

Big power! Â

  The top edge of the firewall has a sharp 90 degree edge which is also backed by the drainage tray for the wiper area.  The drainage tray has many compound angles making it stiff in the fore and aft direction. Nissan thought it strong enough to mount the hood latch there.  On either side of the hood latch area, behind the firewall, in the drainage tray, there are two fore-aft vertical gussets that complete a semi-box section just under the windshield.  I beg to differ that the area is inadequate for assisting in strut top location.  Sure it also depends on where and how you mount to the firewall.  The bar I am using is not the only bar on the market that makes use of this convenient area.  Don't forget, it's not for handling "roll-cage" forces.  It's just a position locator. Now look at this!  You likely aren't going to find a much stiffer box section anywhere in the car.  Looks like wing structure from a Japanese Zero!

Must have been one heck of a cold front! Â

 I too thought that the strut tower bars would have helped.  I figured it would keep the towers from moving in and out towards each other in bumps and turns.  As it turns out, I never realized what I was missing until I got a triangulated bar that tied into the firewall.  Having pivots at the mounts makes them even less effective, unless you triangulate to something solidly tied to the unibody, like the firewall.  The rear bar can be triangulated down to the floor of the hatch or at the base of the strut tower.Â

When all else fails, use a vice grip or a miniature pipe wrench. Â You will need to replace the fitting before you put it back together though.

 Congrats!  Should be fast as greased goose poop!!! It may be crappy cell phone pics but it runs on Windows 7Â

I agree with what he said ^ Â Matching the wheels is a +1. Â That makes it work. Â Are those the rare metal side mirrors or are they the plastic ones. Â I have the metal ones on my 280 and cannot find them anywhere anymore. Â I don't think the mirrors would look bad in orange as a second option. Â The handles, bumpers....etc. look just fine in metallic.

 Those carbs are HUGE if you are running a stock 240Z motor.  That can lead to transition difficulties as the air velocity in the chokes is very slow.  As far as your idle problem goes.  It sounds to me that your linkage is binding and/or the carbs are out of synch.  You also want to make sure that the butterfly's are blocking all the progression ports at idle so that all of your idle mixture is passing through the idle mixture volume screws.  Do your carbs have air-bypass screws?  If so, you want to close them off to get the tuning right.  Oh, and tuning a dirty weber is like pissing in the ocean.  Clean those suckers up if they are getting a bit old.Â

 Love the overall cleanliness and attention to detail.  I also really like the blacked out trim against the orange.  I hope I can see it soon.Â

The ZXT ECU got it's power from the fusible links that were on the pass. inner fender. Â Those links fed the two original green relays built into the ZXT harness. Â When you stuff the ZXT harness into an S30, you will get an 8 pin connector under the dash that has no where to connect in the S30. Â This method uses the original Fuel Pump Control Module from the ZXT and ECCS unit. Â The Fuel Pump Control Module case needs to be grounded. From a slightly foggy memory, you need to: 1) Send high current power to the contacts in the green ZXT ECCS relay. Â I think the control for the Fuel pump relay is already wired in the ZXT harness. 2) Send a switched 12v wire to the control side of both green relays. (from the S30 ign sw.) 3) You need to connect 5 wires to that ZXT 8-pin connector that is now under the S30 Dash. (see drawing) 4) Try to make sense of this diagram. I sketched it while upside down under the dash. Wire to the normally open sides of the relays. http://forums.hybrid...ram-DRAFT-1.jpg I hope I helped and didn't make things worse! Â

 I also have a question about running poor atomization.  If the fuel were poorly atomized when it got to the combustion chamber, what would the AFR's read, compared to the same mass of air and fuel injected with proper atomization?  Would they read lean and cause a closed loop system to increase injection, or just the opposite?  Certainly HC would be UP.  It's highly likely that my injectors were toast, even though I had them cleaned and flow tested, explaining why the carbs smell better. Â

Thanks, BJ.  You summed up what I had a hunch "might" be occurring.  Put aside all the tuning, and jetting.  I have seen my injectors fire, albeit not into a vacuum, and they look more like garden hose than mist.  These are the injectors I am running in my turbo car.  I don't want to compare that car with the Weber car or with factory Z injectors.  I just want to show what the spray pattern from an injector can look like.  Keep in mind, liquid fuel resists ignition, when you see this: That does NOT look like a well dispersed, fine mist. This looks much better, and I am glad the guy's cell phone didn't ring!   When playing with Webers, I have seen a fuel mist resembling a foggy day on the west coast; (Tony no I am not assuming because I saw that, the carbs always fog fuel like that) certainly finer than what I see on the first video of non-direct-fire injectors.  Thanks for the Weber tuning tips.  I have read almost everything there is about Weber carbs, and have played with DCOE's for about 25 years. I feel I have a really good grasp of what is going on inside them. I hope this post sharpens the coordinates of where this thread is going.

Fart out loud and you think someone called out your name. Â Priceless. "The Fart Whisperer".

OK. Â The weber fed version of the motor still smells less than the FI motor. Â I am not making up stories. Â At idle, which is a condition where I can control the volume of A/F mix on the Webers, to obtain a "nice idle", the motor smells better than a "nice idle" obtained with timing, air bypass screw on the AFM, and throttle stop, on the factory EFI. Â Is my observation wrong? Â Tell me. Poor anecdotal stories? Â Wow.