carburetor over flows need help

[turbino]

I have @ 1969 datsun pickup 521 just pick it up last week. I'm having issues with Carb it starts right up then 30 seconds later it over flows I think is the original Carb Nikki I removed the 3 screws then glass shield took the floater out nothing wrong with it ...please help

[ggzilla]

There are two common problems that cause this:

 

1. Fitting an electric fuel pump that develops more than 3 psi

2. A bad needle-and-seat valve, which is part of the $20 rebuild kit

[turbino]

It has the original fuel pump. Is it eazy to get to the needless without braking apart the carburetor? Thanks for the fast reply ggzilla

[ggzilla]

Not sure of the Nikki, but it looks like you undo the fuel line then unscrew the valve -- if so it will be easy.

[turbino]

Had the carb running good then took the truck out for a spin carb is not flooding so that's good but wen I hit the gas it ran like s*it. Losses power

[ggzilla]

No suprise that's its still not running correctly -- if you haven't changed anything.

[turbino]

Did the rebuilt kit work on it. Still not running good. I need help I don't need sarcasm thanks

[ggzilla]

No sarcasm intended. You didn't say that you had done any work to it, you only said "Had the carb running good then took the truck out for a spin".

 

If the symptoms changed after you fitted a rebuild kit, then it suggest (1) it fixed the overflow and (2) it caused a new problem.

 

Did you "rebuild" the carb, or just fit a new needle-and-set valve?

[turbino]

I got it rebuilt. I heard this nikkis carbs are no good. What would be a good carb to get? thinking of junking the one I have.

[ggzilla]

Nikki carburetor is good. Unless it's worn out. A weber is also no good when worn out. I'd recommend getting another Niiki.

 

But if the only problem was overflowing gas, then just changing the seat valve is all it needs. Rebuilding any carburetor is tricky, and if any part is put back in incorrectly it will probably run but not run correctly.

[turbino]

I took it to a friend he claims his a good at rebuilding this carbs, ill brake it apart my self would u know of any web sites that show u the brake down of this nikkis?

[420n620]

any web sites that show u the brake down of this nikkis?

 

you can find the carb under the 520 section

http://www.olddatsuns.com/

or

the carb is on page 39.

http://www.davidcmurphy.com/olddat/data/520Manual.pdf

[turbino]

Broke down the carb today dosent over flow and runs like a champ thank u guys...

[turbino]

Okay drove the truck to a friends house ran fine way back it starded to over flow again. This time I know why the float works fine as soon as it fills up wt gas the float comes out of the pin just enough to get it stuck their for it over Flows...does anything attaches on the pin? Like a safety rubber washer?

[datzenmike]

Yes it's called the float pin collar and is between the glass and the float and acts as a spacer. As soon as the front glass is removed it's the first thing to fall off and get lost. In fact it may have been missing all along.

 

It looks like a small brass tube about 1/8" long and just large enough to slip over the end of the float pin. The Nissan number is 16062-11200 about $0.50 if available. Make something up.

[ggzilla]

The breakdown sheet comes with a carburetor "kit". Here's the part in question (#9 in the photo):

 

[turbino]

Yeah that's the part #9 I made something like it hopefully it works. Not sure how the fundamentals of a float works. Wen it gets full of gas the float hits a pin then it shuts the gas right? Thanks for that picture zilla

[datzenmike]

The pin you see is just a hinge the float swings up and down on as the fuel level varies. When the level drops the float lowers down and and is no longer holding the needle valve up inside the inlet valve assembly and gas under pressure from the fuel pump forces it's way in to re-fill the float chamber. As the fuel rises so does the float and it applies enough pressure against the needle valve that it pinches off the fuel entering to prevent over flowing.

[turbino]

Okay wen the float hits the pin gas still comes out like it wants to flood. Is that normal

[oldschool90]

Maybe you need to adjust the float needle?

[datzenmike]

Well I suppose there may be dirt or foreign material caught in the needle valve preventing it closing. Or the float is set too high and there isn't enough upward pressure to close it.

[ggzilla]

Okay wen the float hits the pin gas still comes out like it wants to flood. Is that normal

 

Not normal. It shouldn't hit the pin. The pin is just a hinge for the float to swing on.

 

The float will float on top of the fuel, and as it rises, the tab will hit the Needle part of the needle-and-seat valve. As it rises a little farther, the needle stops the fuel flow.

[turbino]

Okay I got the truck running sounds good doesn't over flow. But I have the choke on full blast how do u adjust the Carb?

[datzenmike]

Warm up thoroughly, choke and fast idle must be off. Set the idle speed at about 650-750 or so. Turn the idle mixture screw in or out untill you get the fastest smooth idle. Lower the idle speed with the idle adjustment screw. Turn the idle mixture screw in until the idle quality worsens, then out until it worsens. Adjust to about half way between where it runs smoothest and fastest. Turn idle speed down and repeat until you cannot improve the idle quality and it is idling at around 700-750 or so.

 

Make sure that the valve lash has been checked and the timing has been set first. You may have to adjust the idle mixture just to keep it running so that you can set the timing. If so, then re check the idle and mixture afterwards as corrected timing and valve lash can upset it..

[yello620]

Hold On, Let me go get my spoon.