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Thread: 1972 Datsun 240z Original Camshaft and Hitachi SU Carb stock needles

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    Default 1972 Datsun 240z Original Camshaft and Hitachi SU Carb stock needles

    Where can i purchase the original Camshaft for my 1972 Datsun 240z? My car has been upgraded with the following specifications:

    New Datsun L24 motor with crank and rods from a L26, special oversized 84mm flat top black coated pistons from D.L. Potter Engineering with E88 Head and Far 311 New Race Cam.

    2 original SU Hitachi round top carburetors rebuilt with race jets / needle.

    I am having stalling problems and really want to go back to stock!! What parts will i need to purchase in total besides of the camshaft based on the above upgrades? Who sells them? I really prefer high quality parts and Genuine Nissan if available.

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    Registered User madkaw's Avatar
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    PM'd you
    Steve
    71 240z,bw-5sp 2.4-40 over,balanced,e-88,big valves,ported&polished, stage2,header, triple Mikuni's 40's
    3.90 Subaru STI LSD

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    What exactly are race jets? And Race needles?
    Bruce Palmer
    Salem Or
    Sales@ztherapy.com
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    Quote Originally Posted by Bruce Palmer View Post
    What exactly are race jets? And Race needles?
    OKAY. Problem solved! The mechanic readjusted the Hitachi su carbs and check on the electronic distributor. He found a loose wire inside that was part of the original distributor and had nothing to do with this electronic one. He also changed one of the front 3 spark plugs which that had turned black due to the misadjustment of the carbs. Now the car is really stable between 1,000 RPM to 6,000 RPM. Once it reaches 6,000 RPM it fails a Little bit. Which direction shall i take? Any advice?

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    Where do you figure your power band is at?
    do you have forged aluminum psitons?
    If you do have a 'race cam", how well do you think the SU carbs will keep up with it?
    Have you done a searching on the Datsun motors and their limits.
    Steve
    71 240z,bw-5sp 2.4-40 over,balanced,e-88,big valves,ported&polished, stage2,header, triple Mikuni's 40's
    3.90 Subaru STI LSD

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    If those carbs are running stock needles, they could be going lean up top. That was very common for stock needles. Fat at idle lean up top. SMs just reverse that.
    Bruce Palmer
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    I would ask you what are you doing with the car. IF it is pulling from 1-6k I would leave it alone. You will not find enough additional HP to warrant a huge change like a cam/rockers/lashpad. IF the car is reliable enjoy it. You are polishing the apple now. You can move the power band around more, but if you pull nicely from 1-6 then I say go with it. Making a car pull harder above 6 grand will make it less drivable at idle. Not UNDRIVEABLE mind you, but less drivable.

    Enjoy what you got working. Large gains will not be had with a cam. You can get more, but think about the cost. Every mod away from stock costs you something and gains you something.

    Just saying, there is not magic formula of a cam that will get you 260 HP from your block and pistons.

    Play with your mixtures or needles, that is cool and fun. But you are talking carb tuning now, so get an O2 sensor and let the games begin.
    1971 240Z HLS30-38691
    93.9% done and getting better every day
    Now with 100% more DATSUN SPIRIT L28 Power
    1968 Datsun 2000 SRL311-03416

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    Quote Originally Posted by Zedyone_kenobi View Post
    I would ask you what are you doing with the car. IF it is pulling from 1-6k I would leave it alone. You will not find enough additional HP to warrant a huge change like a cam/rockers/lashpad. IF the car is reliable enjoy it. You are polishing the apple now. You can move the power band around more, but if you pull nicely from 1-6 then I say go with it. Making a car pull harder above 6 grand will make it less drivable at idle. Not UNDRIVEABLE mind you, but less drivable.

    Enjoy what you got working. Large gains will not be had with a cam. You can get more, but think about the cost. Every mod away from stock costs you something and gains you something.

    Just saying, there is not magic formula of a cam that will get you 260 HP from your block and pistons.

    Play with your mixtures or needles, that is cool and fun. But you are talking carb tuning now, so get an O2 sensor and let the games begin.
    Just got stucked in a traffic jam for 20 minutes on saturday, bumper to bumper. RPM tended to lower from 1,100 to 800 and then 500 RPM. Had to pull the choke or step on the gas so the car engine wont shut down. I know its difficult to idle on a car that has a race cam but how do i do then? I want to load an AC System on the car but with this type of idling issue it seems i am screwed up. Any advise on how to determine if the is some vacumm escape?

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    Quote Originally Posted by madkaw View Post
    Where do you figure your power band is at?
    do you have forged aluminum psitons?
    If you do have a 'race cam", how well do you think the SU carbs will keep up with it?
    Have you done a searching on the Datsun motors and their limits.
    Okay, Im just about to change this Far 311 Race Cam which was installed by DATSUNLLC and was advised the following:

    "a L26 crank makes your motor 79 mm stroke instead of the stock 73.7 mm
    stock bore is 83 mm for the L24 and the L26 motors
    your block has been bored out 1 mm to compensate for wear
    that makes your motor a 2.627 liter motor
    your E88 head from 1972 will give you about 8.7 to 1 compression
    FAR performance went out of business in 2002 so I have no cam specs
    311 could be their advertised cam duration
    if it is the same as BRE 311-------

    BRE 240Z 311/C-1 cam: At 0.001" lift: In open 33 deg Bef TDC In close 66 deg Aft BDC Ex open 66 deg Bef BDC Ex close 33 deg Aft TDC IN Lift at TDC 0.108" Total Lift 0.463"

    At 0.050" lift: In open 14 deg Bef TDC In close 45 deg Aft BDC Ex open 45 deg Bef BDC Ex close 12 deg Aft TDC

    IN Lift at TDC 0.108" IN Lift Total 0.463"

    EX Lift at TDC 0.097" EX Lift Total 0.469"

    Okay, bottomline, my car is not presenting a smooth idle even though i removed the EGR system. So i believe i should go back and install a stock cam from a 1973 240z which i was sold from a friend. What else will i need. My main purpose is obtaining a smooth idle and being able to install an AC system to the car.

    Please advise what parts will i need besides the lash pads?

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    So this a DatsunParts LLC engine? I don't think that you've mentioned that in any other posts. Interesting that he used a cam from a company that went out of business.

    Your best option would probably be to buy a complete kit from one of the well-known suppliers, like MSA or Schneider. It will be expensive, you'll need the cam, 12 rocker arms, and 12 lash pads. Might be cheaper to just buy a whole head.
    1976 280Z, with some minor modifications

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    As you surmised, a less than smooth idle is a typical compromise you expect when using a higher performance cam. How bad is the idle? Just a bit rough or loping?

    Also, the previous question about where in the rev range your power band falls can make a difference in drivability.

    For what it's worth, mine has a slightly rough idle that initially bothered me. Now I kinda like it...
    Julio
    1972 240Z (in-progress, 95% complete)
    CZC# 15388

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    Its a bit rough. The symptoms are the following:

    Start the engine, drive on free way and everything is fine. Under this circumstances it idles between 1,100 and 1,200 rpm. However, if i get caught in a heavy traffic jam the car starts stalling and decreasing from 1,100 to 800 rises again to 1,100 and occasionally goes to 500 rpm tending to shut the engine down. In this situation i reach to my destination and let the car idle at the parking. RPM starts lowering and eventually shuts down. It does start back again but i have to give it some gas pedal.

    I have already sprayed carb cleaner to all the hoses and connections looking for vacuum leaks and have found none. I did remove the EGR system including the servo diaphgram as it was broken as shown:

    Click image for larger version. 

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    Hope one of you can point me out to the correct direction so i can solve my problem.
    Last edited by jalexquijano; 10-04-2014 at 07:21 AM.

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    Sounds like a vacuum leak/tuning issue.
    2/74 260Z

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    Those cam specs look like my Schneider Cam stage 2 -which should idle like normal-not 1100 rpm.
    Steve
    71 240z,bw-5sp 2.4-40 over,balanced,e-88,big valves,ported&polished, stage2,header, triple Mikuni's 40's
    3.90 Subaru STI LSD

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    Took the car again back to my mechanical engineer. Tested the car and it seems to accelerate fine. The problem is in the deceleration. When coming to a stop sign, slowing to make a u turn or traffic light the car tends to lower the revolutions from 1,100 to 600 tends to stall but immediately goes back to 1,100 RPM. THis is not normal, something is wrong here. After a couple of tests the needle now reads empty on the tank and the car is now shutting down completely even though there is still fuel present in the fuel filter (mine is a glass fuel filter which can show any impurity in the line). The engineer did tuned up the car and changed all the spark plugs in front of me.

    Do you guys think i can solve this issue by myself or should i take the car back to him again? We are thinking on replacing this Far 311 race came with the Original Stock cam so i can get a smooth idle and use my car as a daily driver. THe spark plugs are getting dark in traffic jams due to the race cam.

    I want to solve the stalling and irregular RPM drop when decelerating first and then swap the cam. Can anyone advise me on how to tackle this problem?

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    Check your brake booster.
    2/74 260Z

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    The original throttle linkage had a dash pot that limited how fast the throttle would close. The control valve for the dash pot is located on the balance tube above the forward carburetor. Your pictures show the control valve with tubing connecting the inlet to the outlet.

    Perhaps some of the more experienced users here can do a better job of describing how and when it originally worked. It is not uncommon for the dash pots to be MIA.
    1971 240Z HLS30A 17574 L24-021025

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    I think LeonV hit the nail head. https://www.google.com/webhp?sourcei...rake%20booster

    But Mr Warner makes a good catch also, inlet and outlet hoses reversed.
    Here's a picture of mine for reference.
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    1972 240Z #918 New Sight Orange
    1977 280Z #305 Light Blue Metallic
    1972 240Z #110 Persimmons Red

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    Just checked and I dont see any signs of rust or impurities in the glass filter. I even checked all the spark plugs and they are burning well. I also sprayed carburetor clear to all the hoses end in the car in order to check any vacuum leak with the car parked on idle and the RPM did not change. Do you think i should also adjust the mixture idle Wheel underneath each of both SU CARBS? The problem is when i reléase the gas pedal i.e. if i speed up real hard on 1st gear and then reléase the pedal the RPM drops to 500 and tends to stall but pick up back again to 1,100RPM. Should i play with the idle mixture wheels underneath each of both carbs? maybe give it a Little bit more counterclockwise?


    Im really fed up with this situation!

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    Quote Originally Posted by LeonV View Post
    Check your brake booster.
    Leon,

    OKAY. Yesterday i removed the air filter, caburetor domes, inner springs and sprayed carb cleaner to both of the 3 screw SU carburetors. I refilled both carburetors with 3 in one motor oil and retightened each and every screw in the air filter and carb domes. Finally i did moved each of the idle mixture nuts a Little bit counterclockwise. Result: The car is maintaning its RPM when decelerating or stopping at an intersection.

    Could this have been the problem??

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    Quote Originally Posted by jalexquijano View Post
    Leon,

    OKAY. Yesterday i removed the air filter, caburetor domes, inner springs and sprayed carb cleaner to both of the 3 screw SU carburetors. I refilled both carburetors with 3 in one motor oil and retightened each and every screw in the air filter and carb domes. Finally i did moved each of the idle mixture nuts a Little bit counterclockwise. Result: The car is maintaning its RPM when decelerating or stopping at an intersection.

    Could this have been the problem??
    It sure could have been.
    2/74 260Z

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