Hello Guys, long time member, first time poster here.
After sitting for 10 years in my garage, i just finished restoring my B310, and I have some issues with my freshly rebuilt carb.
The carb keeps carbon fouling the spark plugs, to the point where the car is impossible to drive. A new set of plugs lasts around 120 miles, and then i have to take them out and clean them. They are not oily, engine is not using oil, just sooty.
I checked everywhere for vacuum leaks ,and sorted all of them.
Checked the carb specification article on here for the B310,and all the jets were the correct ones, besides the PRIMARY SLOW AIR BLEED, which was 60 instead of 170. Could that be the reason why the car is running super rich.
My car has the A14 with 5 speed, recently converted from auto.
Are these the correct jets for a European B310?
Primary venturi 22
Secondary venturi 27
Primary main jet 104
Secondary main jet 150
P main air bleed 65
S main air bleed 60
Primary slow jet 46
Secondary slow jet 50
P slow air bleed 170 (x60)
S slow air bleed 100
Power jet 60

And another thing that i'm not sure of, is the accelerator pump. Should it be relaxed when the gas pedal is untouched ,or slightly pushed down. I have two different accelerator pump levers, and i cannot remember which is the original one. One leaves the pump completely relaxed, the other keeps it pushed in about a quarter.

Hope someone is still around here,and is able to give some advice.

Thanks,
Thomas

Welcome Thomas after being shy for 17+ years :)
Means Datsuns are reliable no need for help usually!

Do you have the 170 jet available?
A small air jet usually means more fuel and a low speeds carbon build up is worse than
at acceleration where usually carb just pump fuel and air with poor precision.

Is that a manual or auto choke?

a friend had similar problem but spark was the issue in that he changed his old oil coil
for a modern unit and also used incorrect spark plug gaps.

Hello,thanks for the reply.
Yes,they are reliable, especially if they sit as garage decorations for 10 years:)
I do have a 170 jet,i installed it because i had no other lead on the issue.For now,the plugs are much cleaner, but i only took it for a short drive.
Car has manual choke.
I also changed the old coil for a new blue Bosch unit, but from my knowledge,the new one is also oil filled.
Plugs are gapped correctly,and they are new,new coil,new high tension silicone power leads,new contact points,set correcly with a dwellmeter.
If the plugs finally stop becoming black,my only issue will be the shaky idle, which i suspect is because the air/fuel mixture is not set exaclty right,but that's another can of worms.Carbs are not my strength.

Pretty sure the air bleed is going to be the problem;

Carbs are simple; to richen the mixture you either aid more fuel (larger jet) or less air ( smaller bleed jet)

To lean the jet add less fuel (smaller jet) or more air (larger bleed jet)

As your car was running extremely rich; putting in the larger bleed/air jet should lean it out and solve the problem.

Depending on how rich it was running you may want to change the oil and some amount of fuel has gotten in it.

The Bosch replacement was the issue with my friends datsun 1000
he went back to the original coil and plug fouling cleared up
even after spark plug change it didnt take long for them to foul

Hello,and thanks for the input.
So it looks like the small air bleed was the issue.I made around 50-60 miles in the car, examined the plugs,and they have 0 soot on them.
Not sure why that 60 air bleed was installed(a carb specialist installed and adjusted the carb last time),and weirdly the car ran well 10 years ago with that air bleed.
Anyways,everythink seems ok for now.

Regards,
Thomas