The idle speed and idle mixture setting is more important than the air bleed.

hI dd

He changed the Fuel Bleed Jet when the carburator is installed the jet that comes under the carb to the rocker cover side,earlier we had 90 size then changed it to 75 and changed it to the 65 to reduce CO but car doesn't pull well and C is increased a lot but normal CO,then again changed it to 75 then car is pulling nicely ,i will give it a try again , now i got 75 Fuel Bleed running it it a normal size to run i am referring
http://datsun1200.com/modules/myalbum/photo.php?lid=13367
either 48 0r 52 part are you referring the same or something else if you can give me the reference no please

thanks
regards
sumith

Carburetor repair kit comes with no jets, because jets do not wear out.

It may pass emmissions if you simply adjust the idle speed and idle mixture. Give it a try.

Hi DD

Is it available with Carburetor rebuild kit ?


thanks
regards
sumith

Sounds like your car is getting into excellent shape. The emissions just needs some carburetor adjustment.

Quote:

When emission technician suggest mixture changes, they usually mean the idle mixture screw.

Larger jet will increase HC. However I think he changed the air bleed. Stock size is about 60.

Changing these does not affect the idle circuit. I see from the results that you idle HC and cruise (2500 rpm) HC both increased.

Suggestions:
1. Replace the larger air bleed with the original one. A too lean air bleed may case misfire, raising both HC and CO
2. Set the idle speed to 800 RPM -- 1100 is RPM is to high for the idle circuit to work properly
3. Adjust the idle mixture per Datsun instructions

Tune-up
Adjust carburetor at full operating temperature. Verify choke is fully open before adjusting

manual: 750 best idle, then lean to 700 rpm

automatic: 800 best idle, then lean to 770 rpm (check for 650 rpm in drive after adjustment)

"best idle" means the smoothest idle (first speed screw, then mixture screw, repeat until found)
"lean" means turn the screw in until the speed drops (mixture screw only)

For minimum emissions and fuel economy the idle mixture should be slightly lean. Petrol engine runs fine from 14:1 (slightly lean) to 12:1 (rich). But at about 14.7:1 achieves minimum emission combination.

Hi Guys

As planned took my car to the Regular that mechanic and he has identified that carburetor throttle shaft and doors were having a problem that it doesn't idle on low rpm, then we sorted out that by putting my b210 throttle part and then car is idling low rpm and run fine and meanwhile we did these basic things

Pasted Valve seat and refaced the head and install a new gasket kit
Changed all 4 Spark plugs and wires
Changed the Ignition coil
changed engine oil and filter and changed gearbox and differential oil.
Replaced the Brake washers including master pump and new set of brake pads.
changed the accelerator cable with a new one
car is running perfect no miss no noise except alternator noise and pulls better.
but i took it to the emission test that i failed it twice
First Result was

Speed(rpm)=1100
HC(ppm v/v)=857 idle,445(2500rpm) (standard required 1200)
CO(%(v/v)=8.73 idle,7.6(2500 rpm)(standard was 4.5)
Lambda = 0.87
O2=3.94
CO2=2.72

They wanted to reduce fuel mixture so changed the carburetor jet from 75 to 65 size
and then again took it

Speed(rpm)=1100
HC(ppm v/v)=1974 idle,1290(2500rpm) (standard required 1200)
CO(%(v/v)=0.26 idle,0.25(2500 rpm)(standard was 4.5)
Lambda = 1.46
O2=10.3
CO2=7.97

this time we gained CO(%(v/v) but lost HC(ppm v/v) and failed any body can suggest what more to be done where is it wrong usually mechanic is a renown person for these cars but still he is unable to guess it what causes this situation.
I had my b210 done few times earlier without changing a spark plug even but i have never failed so any suggestion guys ? i am little pissed out with this situation now

thanks
regards
sumith