Gershwizzle

iTrader: (1)

Car is an '83 with a 12a, rats nest removed, and the only thing I haven't stripped from the carb is the float bowl vent solenoid and the choke.

I just rebuilt the nikki carb, the car starts up and idles fine, but I'm running into three problems.

Problem 1: Float bowl levels are messed up. Before I rebuilt it, both float bowls were filling up perfectly to half way. After the rebuild, the firewall facing bowl looks to not be filling at all (maybe it's overfilling past the sight glass so it looks empty?) and the front facing bowl is filling up to the very top of the sight glass.

I was hoping this was just I forgot to burnish the new float needles and they are sticking, but Ive probably driven five miles and this hasn't changed. What do???

Problem 2: This is why I think the firewall float bowl isn't filling at all, but regardless of adjustment, my accelerator pump isn't pumping any fuel. I can slowly climb my rpms to get the car rolling, but if I put my foot down much at all, the car stalls out.

Problem 3: I have vacuum secondaries hooked up. Before the rebuild, they worked fine. Now, the secondaries don't feel like they are opening at all. At around 5k rpm, the engine feels powerless. I'm guessing the diaphragm got messed up during the rebuild, but I'm not sure how to check this. With my hand, I can open the secondaries just fine. I want to keep the mileage of vacuum secondaries, but if the diaphragm is broken, I may just convert to mechanical secondaries... How do I check the functionality of the secondary diaphragm?


Thanks in advance for any help guys, looking forward to getting this car running perfectly so I can move to my suspension problems!

Also, if pictures will help, just let me know what I should snap and I'll put them up here.

Cookboy

iTrader: (10)

I'd take out the needles and use a scotch brite pad or something to smooth them out. If you were careful not to mess with float levels it oughtn't be the floats.

The acc pump check ball and weight must be in below the nozzle. I think there's another check ball near the diaphragm. They are vital.

I use mechanical secondaries and they only open when I want them to.

Taking the carb apart again after a rebuild is not uncommon. Not for me anyway. You'll have it right in short order I'm sure.

t_g_farrell

iTrader: (1)

Definitely don't mess with the floats if they were good before. Double check everything you did
against the exploded diagram and make sure all the right spec parts got put back into the right
holes. Sounds like you may have check ball issues as Cookboy pointed out as well.

Gershwizzle

iTrader: (1)

So I figured out one of my problems. Turns out I put the gasket in between the throttle body and main body on backwards. After flipping that, my secondaries are working again.


Second, when I took the airhorn off, one of the floats was way off spec, so I adjusted it to spec as per the carb rebuild manual, which ended up making the floats symmetrical. Put the carb back together and now the floats are equally high, with them filling up just to the top of the sight glasses. How do I bring these levels down?

And my third and biggest problem, the accelerator pump isn't working at all, essentially making the car impossible to drive (engine will stall if I give it any gas quickly from a stop, and when I touch the gas while moving, the car wants to lurch back and forth repeatedly before settling into the throttle). I cleared all of the passages with carb cleaner and air when I took it apart and made sure to get the checkballs and weights in the correct spots as well. Any ideas on why it's not working? Is my only option to take the carb off the car again to open the accelerator pump diaghram up to see if something is wrong?

Jeff20B

iTrader: (13)

One of the little metal ***** might be stuck. There are two.

DivinDriver

iTrader: (15)

On the float levels, the relationship between the fixed height of the float pivots, and the point at which the needles have to contact the seats can vary in a few ways.

If you changed out needles and seats, you may have changed this relationship slightly.

Make sure:
1) Needle seats have proper-thickness crush washers (usually aluminum, some kits give fiber ones instead) between them and the carb lid. If those got thinner (or got left out), the seal point on the seat will have risen & the floats have to rise higher to shut off the gas.
2) Springs are installed inside the needles for the feeler pins to ride on; people have been known to miss those tiny springs when assembling the needles, and that makes the needles effectively shorter.

Cookboy

iTrader: (10)

Accelerator pump diaphragm in backwards?

Gershwizzle

iTrader: (1)

DivinDriver, I used the same washers that were already in the carb for the needle seats, and the springs are installed inside the needles along with the little plunger that fit inside it as well. Also, neither checkballs are stuck.

Cookboy, that is my guess as well, and I am going to check the diaphragm the next time I see my car.

I figure there are 3 components to the AP: fuel getting to the circuit, the circuit itself (blockages), and the diaphragm. I made sure to clean out the circuit before I rebuilt the carb, even though my float levels are high, the AP should still function (I don't see why not), so my only guess is the diaphragm is put in wrong, although I don't know how I would goof that one up..
I'm about to be real frustrated if I have to take off the carb again only to find it is on there correctly!

Gershwizzle

iTrader: (1)

So an update if anyone ever runs into the problem I had with my accel pump:

I took it apart and it turns out I put the spring on the wrong side of the diaphragm. Reassembled it correctly and the problem is fixed! Mostly at least, the car wants to stall out for the first minute or so I turn it on if I touch the gas, but after it warms up at all, the problem goes away. The car still wants to bog a little if I stomp on the gas from little to no throttle, but I think that's just a matter of messing with the adjustment nut.

After putting around 100 miles on the car since I last messed with the carb, my floats are still too high (they fill up to the very top of the sight glass) . Is there a reason my floats would change in height so much after a rebuild? Should I just take off the airhorn and bend the tabs until the float level sits right?

kutukutu1

iTrader: (5)

Don't get frustrated with the carb. I took mine out 28 times. I think is a right of passage for 1st gens. I also had high fuel bowl levels. I would adjust them to midway on the sight glass. Mine with levels like yours would not run right or idle properly. Also, just in case I always tell members that have a rats nest removed and rebuilding carbs to insure not to plug the fuel bowl vent tube the to the left of your fuel inlet. Plug that and everything will look good until the secondary's open and dump a lot of fuel which will stall the car and flood it. Left me stranded 5 times, till I figured it out. Good luck