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Blue is now 240260280

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  1. Blue is now 240260280

    Setting Fuel Level Weber DCOE

    Had fun with my good buddy Dr240z refining the tuning of his triple webers. The last time we set them we used a fuel level of 25mm below the cover-body margin (as per Keith Frank's recommendation). It turns out this is way too high and caused the cruise to be too rich... something that could not be tuned out. Idle and WOT were easy to set however. This time we set the fuel level to 29mm and used a new rig to do this as precise but much faster than the pipette method or the caliper method. It turns out that a column of water 8' to 9' high "head" gives a pressure of 3.5 to 4 psi at the base (simulating that of the fuel pump on a Z.) so we strung a funnel and hose near the garage ceiling and ran this into a carb lid on the floor. The carb lid sat on a clear plastic tub with water levels from the top scratched into it for reference. the top of the tub represented the top of the carb body. By filling the system with water, it flowed through the needle valve at ~ 4psi. When the flow stopped, we measured the fuel level and bent the float tabs as required to get 29mm. Once all 3 carb lids were the same, we continued tuning and finally dialed in the carbs to a powerful yet non-stinking/non-fume delight at idle, cruise, and WOT. FYI: Gasoline would have been more accurate but water worked and was safer. FYI the S.G. of gas is ~0.70 so a float would sink lower in it. 9' Head 29mm fuel level The Doctor This post has been promoted to an article
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    Quick and dirty SU Tuning

    For balancing the carbs here are a few quick and dirty methods I use when I don't have a flow meter or WB A/F meter: Setting Idle 0 Assume good plugs, valve adjustment, no vacuum leaks, good fuel pressure and float levels set correctly. 1. Remove air box 2. Warm up car and remove all linkage connections so that the carb's throttle plates are resting on their set screws. 3. Adjust each set screw so that the suction felt when you put your knuckles against the throat of each carb and feel the air flowing between your fingers is the same on both carbs. 4. Stick you head down between both carbs and listen to the intensity of air whistling sound from each carb. It should be the same amplitude 5. Repeat 3&4 until happy and your rpms are 600-800rpm (exact rpm should be suited to your taste and performance when moving from stop or what the FSM states... your call baby) Setting Off Idle 6. Reconnect linkage 7. Make sure the screw from the fast idle servo is not pushing on the throttle rods (that screw is the one next to the front carb). 8. Turn the fast idle screw at the center of the linkage (way up high) so that the car is idling ~ 3000 rpm 9. Adjust the balance screw on the linkage (next to the back carb) so that the air flow is the same in both carbs (as you did in 3&4 above) You can also observe the point at which both throttles open when you push the main linkage. The balance screw should be set so that both throttle plates open at the same time. Setting Mixture 0. Warm up car 1. Screw both jets all the way up to the top 2. Screw the jets down 2.5 turns (default starting point) 3. Take the car for a run and listen closely for popping in the exhaust (rich), popping in the intake (lean) and note power 4. Screw both jets up or down 1/2 turn and take another run to see impact. 5. Repeat 3&4 and do 1/4 adjustments until you are happy 6. Take the car for a spirited 30min drive with plug wrench then while driving fast on a long stretch, hit clutch, kill motor then pull over to side of road, look at all plugs and compare colour. If there is a difference between the front 3 and rear 3 then the fuel jets need tweaking. Adjust the darker 3's carb by turning up the jet to lean the mixture a 1/4 turn If all plugs are too dark then turn both jets up 1/2 a turn. 7. Repeat 6 until you are happy. All plugs should be the same colour and very light brown. Listen for popping out the front to tell if you go too lean. Don't worry, you can take your time and do this leisurely over a couple of days to fine tune and colour match your plugs. Power and Timing 1. Fill up with premium gasoline 2. Advance timing to 10° BTDC 3. Grab a 10mm wrench 4. Take car for a run and note power 5. Pull over and use 10mm wrench to advance timing a bit (turn distributor clock wise) Don't worry about a timing light 6. Take it for a run and note power increase and listen for pinging under load (try acceleration on a hill to force a load) 7. Repeat 5&6 until you are happy with balance of power vs. pinging 8. Check plugs again. You may need to add more fuel to get the last bit of power 9. Make note of timing at idle using a timing light. Follow Up 1. Turn each jet up and count turns. Record these numbers for future reference then turn the jets back down. 2. Measure timing with a timing light at idle with no vacuum advance and at 3000 rpm Record these numbers. Aim for 36 to 38 maximum degrees at 3000rpm. 3. Measure engine vacuum and record number. 4. Measure air flow (with proper device) and record numbers 5. Measure O2 with WB at idle and at various RPM's underload and record numbers. 6. Re-balance carbs at idle and 3000 rpm's with airflow meter. 7. Adjust jet height using WB O2 sensor. 8. Close mouth of each carb (one at a time) set rpm to 3000 and run rough on one carb and measure with WB. Compare both carbs and strike balance. (AF ratios should be the same and rpm's the same when running on one carb) 9. Do the "lift each piston 1/16" and compare how engine behaves as well as "Norm's lift each piston fully to disable" trick to also compare each side to the other's behaviour. 9. Measure 02 with WB at various rpms' under load and select or augment needle to taste. Repeat 9 until happy with WB and butt dyno performance. 10. If you have the luxury of a dyno then use it. 11. Once jets and needles are set Blueprint (measure evertyhing) including depth of jet from bridge of carb with vernier caliper's depth gauge.
  3. Blue is now 240260280

    1972 240z Factory Service Manual

    Version

    47 downloads

    1972 240z Factory Service Manual

    Free

  4. Blue is now 240260280

    1978 280z Factory Service Manual

    Version

    77 downloads

    1978 280z Factory Service Manual

    Free

  5. Blue is now 240260280

    DCOE Throttle Spring Testing

    The Spruell Motorsport shipment just arrived with the stronger Weber 40 DCOE Throttle Springs. These springs are used to firmly close the throttle plates shut. This ensures consistent performance as explored and discovered in this thread: http://www.classiczcars.com/forums/carburetors-s30/48969-weber-internal-spring.html For reference, here are the Weber part numbers: 47605.012 Weaker 47605.027 Standard 47605.009 Stronger I decided to measure the spring constants of the springs I had on hand for reference: ?????????? (is from Pierce Manifold sold as 47605.009 BEWARE) New 713.2 N-m 526 Ft-Lbs 47605.027 Used 1,634.4 N-m 1,206 Ft-Lbs 47605.027 New 1,669.2 N-m 1,231 Ft-Lbs 47605.009 New 2,203.7 N-m 1,625 Ft-Lbs I am not sure of the age of the used standard spring but it has not aged much.Clearly Pierce sent the incorrect spring.The stronger .009's are ~ 33% stronger
  6. Comparison Photos: 280z on left 240z on right Front (note 280z screw hole) Bottom Top Back Back Harness (Note white current loop on 240z and red voltage pickup wire on 280z) 280z back (Green is 12V and black is ground) 280z and 240z connector comparison. (Note the different locations for Gnd and +12V. It is neat to see the location for the tach signal input is in the same part of the can...clever engineering and evolution).
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    Need Parts for Early 240z

    Interior Hatch Area Panel that Covers Tail Lights: No access holes for bulbs: Early Water Pump (Smooth) Rad Cap (with Japanese Text)
  8. One of our largest national car parts supplier in Canada is Canadian Tire. I needed new front wheel bearings for #249 so I checked them out... "National Bearing" Made in China. I tried a local supplier and requested Timken. They could only obtain SKF:. Part # 18864 Inner Seal (Taiwan) Part BR2 (LM11949 / LM11910) Outer Bearing and Race (Japan) Par BR6 VP Inner Bearing and Race (Brazil)
  9. Blue is now 240260280

    Blue is now 240260280

  10. I am exploring Weber carbs and decided to try to simplify and present their functioning so that others can quickly grasp the basic concepts. To do this, I decided to make a fictional path of design that Mr.Weber, may or may not have traveled. I will provide further details for operation and maintenance in future posts, however this first post is a very simplified introduction. Blue The Ideal The simplest carburetor design that comes to mind would be a tube to flow air with a source of gasoline spraying in the middle of the tube. This would provide even distribution and symmetrical mixing at the highest velocity point of the tube. Approaching the Ideal: The Main Circuit The Weber carb commonly used on Datsuns is basically just a tube with a fuel nozzle in the mid-stream of the air path. Unfortunately another part was required.... the Throttle Valve. To control the amount of fuel and air drawn into the engine a throttle valve was added. Its location was chosen to be downstream from the fuel nozzle as the manifold vacuum on the motor side of this valve would otherwise suck the fuel from the fuel nozzle when the throttle valve was closed. The main drawback of the throttle valve location being down stream is that it still blocks the air flow when open and, fuel sprays over it and can also be deposited on it. In addition to a simple tube with a fuel nozzle design, Weber shaped the tube so that it was narrowest where the fuel was drawn into the air stream by using the Venturi principal. This promoted fuel draw and fuel distribution. It is interesting to note this simple tube and nozzle design is nearly identical to a modern high performance fuel injected individual throttle body (ITB) manifold architecture. Reality and The First Corrective Actions: Adding the Idle Circuit and the Emulsion Tube Unfortunately for Mr. Weber, the above design was only marginally optimal for middle to wide open throttle and it failed completely at idle. Here are the main problems that he faced: At lowest rpms (Idling) when the throttle valve was nearly closed, there is not enough air flow over the main nozzle to draw fuel. (Lean) At higher rpms when the throttle valve was moderately to fully opened, the air fuel mixture became too rich as too much fuel was drawn from the main nozzle. (Rich) Weber was not beaten as the fundamental design worked in principal and could be modified to work. In fact the above design is actually the so-called “main circuit” of a Weber carb. Onward: The way Weber addressed these two problems of fuel flow at both ends of the RPM spectrum was: To address idling lean, Weber knew that the main nozzle was no where near the high velocity air flow so he added a new and totally separate second so-called “circuit”: the idle circuit. Basically he added a needle valve on the high vacuum downstream side of the throttle valve. This needle valve independently controls the amount of pre-mixed fuel and air (mixed upstream and not shown for simplicity) to flow past the throttle valve and feed the engine when the throttle valve is nearly closed (and the main circuit was not functioning due to low air flow). The simple one circuit carburetor now becomes a two circuit (Main and Idle) To address the need to lean the mixture in the main circuit as the throttle valve approached "Wide Open Throttle valve" (WOT), he added a “fuel/air mixing tower” with holes in it called an “emulsion tube”. Air and Fuel mixing took place in and around this tower before the fuel was drawn out of the main nozzle. Fuel entered the tower at the bottom of a well and air entered from the top. As the fuel demand increased approaching WOT, the fuel level in the tower& well lowered and in turn exposed more air holes thus mixing more air with the fuel. This ultimately leaned the mixture (as required) in the main circuit as more airflow through the carb occurred. Emulsion Tube Weber now had a 2 circuit carb design: One being the idle circuit and the second being the main circuit…. But how to switch from one to the other slowly and quickly? Dealing with the Transitions: Adding the Progression Circuit and the Acceleration Circuit. The Progression Circuit (for slow transitions from Idle to Main): Weber found that, as the throttle valve slowly opened, when transitioning from the idle circuit to the main circuit, the air flow required to activate the main circuit did not occur quick enough. This delay in the main circuit starting caused a lean spot between idle and main. The solution used by Weber was to simply add more fuel holes near the throttle valve. These holes were drilled upstream of the idle needle valve port. As the throttle valve opened, it exposed each successive hole to the manifold vacuum. In turn, (due to high velocity air and manifold vacuum) it would draw more mixed air/fuel from each progression hole. For economy, the source for air fuel Weber used was the idle circuit. The Accelerator Pump Circuit (for fast transitions from Idle to Main): Weber found that if the throttle valve opened quickly (when transitioning from the idle circuit to the main circuit) the progression circuit above did not have enough time to operate as the airflow suddenly was across the whole carb throat rather than up near the roof and progression holes. This sudden bust of air and delay in the main circuit starting caused a lean spot between idle and main. The solution used by Weber was to add more fuel by using a one-shot-squirt-gun-like pump that was activated on a quick throttle opening (hammering the gas pedal). The design also had a clever feature where slow throttle valve openings did not squirt additional fuel (to be shown in more detail in subsequent posts). Summary: - A Weber side draft carb used on many Datsuns has two independent "circuits": The Idle Circuit and Main Circuit). - A so-called Progression circuit is used to aid in slow rpm transitions from Idle Circuit to Main Circuit. - A so-called Acceleration circuit is used to aid in fast rpm transitions from Idle Circuit to Main Circuit.
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    Quarter window removal

  12. Blue is now 240260280

    Merry Christmas, everyone!

    Mrs Claus was nice this year: http://www.restofab.com/Z-Silhouette-key-holder_p_15.html
  13. Blue is now 240260280

    Holiday Choir

  14. Blue is now 240260280

    Understanding a Weber Side Draft Carburetor Through a Fictional Supposition.

    3mm below the side wall is too high. Bumps and turns will cause spill into the main passage. 29mm down is the place to be. In practice, you can tune at any height given the adjustments available for every circuit however you will make some compromises in most cases. My experiments with the fuel ridiculously high at 25mm down (as championed by an internet sidedraft "expert") made me waste a lot of time. After I finally tried everything and then questioned the 25mm fuel height, I discovered 29mm was a good place to be. It was verified by expert Japanese tuners who made this fuel level tool that Grannyknot gave me: And another reference to 29mm: http://www.carry-back.com/CARRY BACK Carbu setting 3.htm
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    Understanding a Weber Side Draft Carburetor Through a Fictional Supposition.

    Opps. I was off the mark. Chickenman pointed to it being an L28. I saw low vin 240z in your signature and assumed L24. 30mm chokes will give you lots of lower end torque (which most of us like) however it sacrifices WOT runs where more airflow trumps. I recommend tuning the 30's now and go bigger if not satisfied, Here is a great thread on a similar quest with an L28. Torque won in the end. http://datsunzgarage.com/weber/
  16. Blue is now 240260280

    Understanding a Weber Side Draft Carburetor Through a Fictional Supposition.

    Hi Duffman, I'm not sure I understand the 16mm fuel level? On 40DCOE the passage to the main circuit is 23mm down, You will want to be ~6mm lower than this at 29mm down from the edge. At 16mm down you will be flooding the main circuit. For Emulsion tubes, Chicken man knows his stuff but at this point I would not worry about changing them. They basically are only in operation at WOT as you run up the rpms from 3000 to 7000 (unless your fuel is too high or main jet is too large). They do have a bit of an impact at high load cruising but you can tune this with the main jet a little. One other thing I forgot to address are the "other" aspects that must be correct before tuning triples: 1. Valve Lash: Engine should be tuned nicely with correct lash set. 2. Intake Manifold air leaks: Absolutely none. This will throw off any tuning. 3. Timing: DCOE's and L engines like lots of advance. 15 to 20 degrees at idle with full at 36 to 38 are typical ranges. No vacuum advance is needed. 4. Linkage: Remove all slop and ensure all three carbs open at the same time and the same amount. btw do you have a device for measuring air flow into each throat? You will need this to tune once you have the fuel level sorted. For your 40DCOE 151's you will find the Idle Enrichment (IE) screws will need to be ~ 1.75 to 2.75 turns out from full stop. These carbs have a narrow tapered needle and are more precise than early Webers that have a wider taper and seem to work best from 1/2 to 1 turn out. Here is some data I collected when tuning and changing the idle jet number of turns on a set up much like yours:
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    Understanding a Weber Side Draft Carburetor Through a Fictional Supposition.

    I found 55F9 Idle jet worked nice on a 240z. It will give you more fuel in the transition and you can dial it back at idle. The lean on hard acceleration seems strange with a 125 main. I wonder if your fuel level is too low? What version of 40DCOE do you have? For the leak, it could be very small aluminum washers that may be missing on the pump jets: Or the aux venturis may not be sealing well against the throat. This could explain the leak and weakness on acceleration. For completeness the choke plungers can leak. If you have them in your carbs you may want to disable the choke cables then ensure the plungers are all the way down. Here is how to check for correct fuel level.
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    Exhaust Header and Year

    Trying to figure out what exhaust headers went with the year for North American Z's Here is a stab: 240z E30 E36 N33 (U98 non-Emissions) 260z E36 280z N42 N47 280zx U87 P71 W48 Corrections, additions are welcome.
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    Understanding a Weber Side Draft Carburetor Through a Fictional Supposition.

    Hi Duffman, No problem. My buddy Ross Parks is in your neck of the woods this winter. Say hi if you see him. The biggest source of leaks with Weber DCOE's are: 1. Fuel Level Set Too High. (27mm to 30mm down is where you want to be) 2. Aux Venturi sealing inside the throat ________________________________________________________________________________________ Some Passini for you too. As mentioned in another thread some good Weber info will be shared in a month or two http://www.classiczcars.com/forums/attachment.php?attachmentid=49393&d=1321585578 Look at the pump leaking at the phillips screw in this video at high rpms. I speculated and discovered then later saw that Passini knew of it all along Nothing new under the sun. Fuel _PullOver_ from accelerator pump squirters..avi __________________________________________________________________________________
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    Datsun-240z Vs Fairlady-z432

    Better photos: http://www.fantasyjunction.com/cars/1907-Nissan-Fairlady Z 432-2.0 Liter Inline DOHC 6-Cylinder
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    Nissan 2400 OHC value cover

    ditto
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    Datsun-240z Vs Fairlady-z432

    One for sale in USA https://www.hemmings.com/classifieds/dealer/nissan/fairlady-z/1873845.html No engine photos????
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    Rear wheel bearings and seals

    The one on the left is the outer. There is a seal that goes on the inside. (below) Read this and you should get a better idea of how to replace your rear axle bearings: CLICK
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    Rain Gutter Drip Rail Removal and Installation

    Some photos for reference.For installing and removing simply pick an end then start rolling with fingers. I found that removing works best starting from the rear and installing works best starting from the front.They clean up well with fine steel wool.*****Addendum by Enrique Scanlo ******Excellent post.A couple of notes to add, having done a few of these.Sometimes due to grime and other schmootz that creeps in underneath, you'll need more help than simply rolling the trim with your fingers. In that case, use a flexible scraper to GENTLY ease the lower edge out from underneath the drip rail. Once it begins slipping off, don't get too over eager in twisting it off as this can cause you to give it a fixed twist that could cause you to kink it.Even after removing it, it may have a bit of a twist on it. DO NOT TRY TO STRAIGHTEN IT OFF THE CAR. If the twist is just a gentle curve, it will go away once you replace it on the car. I've seen perfectly straight trims get mangled because someone tried to "straighten it back to shape", and trims that seemed corkscrewed out of shape go back on perfectly well.Personally, I wouldn't use steel wool on the trim unless it was severely scratched and gouged, and then I would take it very slowly. I prefer some of the metal polishes on a rag after cleaning with lacquer thinner. But, your experience with the steel wool or polishes will be the deciding factor.Again, excellent post Blue. I'm promoting this to another excellent Technical Article by Blue.Enrique ScanlonModerator
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