Alright so I took apart the NIKKI and did some cleaning via the blast cabinet. I also replaced whatever gaskets I could using rubber-fiber material from Fel-Pro.

Now the problem I have is that after this mild rebuild, the carb will end up flooding. I've been running an electric fuel pump even prior to taking things apart and it seemed to work just fine. It was hooked up to the coil and provided constant fuel pressure without flooding the carb.

Now, it seems as if the fuel pressure is so much higher that it overcomes the float needle valve and floods the carb, fuel practically shoots out of the two brass pipes at the top of the carb.

Any ideas why this might be? I'm thinking something more regarding the carb since nothing happened with the fuel pump.

In addition, outside of the throttle speed screw, and the idle screw on the driver's side of the carb, are there any adjustments on the NIKKI? Also, what's the difference between these two adjustments?

Wow, old school. I'm game to try it; I'm old enough to remember how to mess with carburetors. I never heard of a Nikki.

I've heard of a Nyakki.



And Prince knew a chick named Nikki.



But neither of them will deliver fuel so I assume this is our culprit?



Shot in the dark, did you forget to install the fuel filter? That might be the restriction that made the difference.

All your vacuum hoses hooked up and pressure tight?

I've never messed with one of these, is the fuel originally pumped mechanically? What are you using for a fuel pressure control?

Fuel filter is still in place. Literally nothing changed outside of rebuilding the carb. Everything is hooked up as it was before.

At the moment there isnt anything controlling fuel pressure simply because prior to this issue, I never had a need for a regulator.

You did overhaul it. The carb may just be performing well now and that has messed with the setup that worked before. The filter is new? A dirty old filter could have served as a passive pressure regulator. I have pinched return lines with hose clamps on EFI systems as an effective McGuyver adjustable regulator.

it was a mechanical fuel pump before, right?

It could be that... Although it's just hard for me to understand why all of a sudden the fuel pressure coming in overcomes the float valve as much as it does. The resistance should be the same shouldn't it?

The truck's been running with an electrical pump since I've owned it. I do have a mechanical pump that I plan to install down the line.

Specs on the electric fuel pump? Are you sure it's designed for carb use? As TMS said, it's possible that the rebuild has caused the carburettor to start working as it's supposed to and now you're not having issues. The only other thing I can think of is that during the rebuild the float was damaged and isn't closing like it's supposed to. I had a Ford Escort that had that issue. The float was plastic and would break down over time and stop closing the valve.

No clue on the fuel pump, there's no labeling on it whatsoever from what I can see while it's mounted. I plan on checking it out later when I get home from work (night shift).

No clue on the float/valve malfunctioning as well. Visually it LOOKS like it's functioning properly, until the entire bowl is filled with gas then next thing you know it shoots out from the top of the carb.

Deerio,

until the entire bowl is filled with gas then next thing you know it shoots out from the top of the carb.

Knowing this I would definitely give the fuel pump a look and see what brand/manufacturer it is. It also sound like the back pressure from when the needle valve closes because the float bowl is full is not enough to turn down/off the fuel pump from pumping. So this could also mean you have a bad fuel pump as is does not know when you float bowl is fuel or it is simply over power the needle valve because of too much pressure. Definitely need a regulator.

Is your 320 still running the OE generator or a later alternator? Modern electrical fuel pumps are really only made for negative ground autos with alternators and not positive ground generators. And could be a reason it may be bad. Yes, positive ground fuel pumps are available from Moss Motors and Victoria British and maybe even your local parts store but you have to ask them for the positive ground fuel pump.

Can you post a picture of your fuel pump? I have an electrical on two of my 320s with no regulator and they run fine. So you might have too powerful a fuel pump.

Andy

So I took out the fuel pump and I could make out the model being SP8012U, and on further research it's a Spectre fuel pump that puts out 5-9 PSI. I have a fuel pressure regulator that's supposed to be delivered tomorrow so i'll throw it inline when I get the chance.

It's really just got me thrown for a loop as to why the carb never got flooded before.

Andy, I'm still using the OEM generator.

Alright so some not so great update:

I got a fuel pressure regulator and hooked it up inline between the fuel pump and the carb. The default setting on it is 2.7 PSI and it flooded the carb... I adjusted it as far out as possible (theoretically the regulator's lowest setting is 1 PSI) and it STILL flooded the carb.

This got me wondering if something was wrong with the float bowl. So I proceeded to take off the glass and removed the float. I then held pressure on the needle valve as if it was being pushed in by a bowl full of gas. Needless to say gas squirted out and around the needle valve anyways.

I removed the brass fitting that the needle valve and spring go into and took a picture:
]

So while looking at this picture, when the fuel pump is on, gas will come out from the space between the brass fitting and the metal insert (that the needle and spring go into).

My question is, is this the normal function? If so, then how does the needle and spring seal it?

Well that was quick... I took the fitting apart and used a ton of carb cleaner and blasted it with 125psi of air for about a minute and that fitting came out! Cleaned it up some more and now it works great!!! Matter of fact, I don't believe I need to regulator again like before!

Any reason to use the regulator if it's not flooding the carb without it?

Okay, now that I'm logged back in.

Glad to here you have resolved your flooding problem. As for the regulator - Yes, I would recommend keeping it in place. As you have noted, the Nikki 2C-3D is good for 2 - 2.3 psi while your electrical fuel pump is rated at 5 psi minimum if not more.

Andy

Hell yes! You took a methodical step by step approach and licked that problem. Good on ya. Keep the regulator on and go rip up the road.

Glad you got it sorted out!