maf

Got it done, and put it together.It starts great, idles sweet,hardly even needs choke- fires right up.Will idle nice at 500 to 600 RPM.
However,seems a little weak at top end, and on emission test,scored 28.2205 on CO GPM ,(45,0000 allowed)
434.1623 on CO2 GPM , NOX GPM 1.4400, (5,0000 allowed).
But failed HC GPM 4.3208 , 3.5000 allowed - "High HC readings are a result of unburned or partially burned fuel."
I have done cap, rotor, wires,plugs,and just for grins - replaced the fuel filter again. dealer air filter.EVERYTHING is dead on stock, and functioning, as near as I can tell.
I pulled it on a level, and looked in the float bowl windows, and the fuel level is right at the top of the window.Is this a problem?
BTW 1982 12A stick,80,000 miles.

innertwist

iTrader: (3)

Ouch. Do you still have your cat? Is the air pump hooked up? Have you heard about wood alcohol...

As for the high end, at the back of the carb there's a spring rod that has to be perched on the linkage in order for the secondaries to open. Everybody always forgets this the first time they do a rebuild. I wish I had a picture for you but I can't find one right now - somebody will hopefully chime in with one.

EDIT: The fuel level should be halfway up the window

innertwist

iTrader: (3)

here we go, this page has a picture of what I'm talking about: https://www.rx7club.com/showthread.p...7&pp=15&page=2

maf

innertwist- the secondary rod, is on the perch. I was wondering if the bowls would spill over, (if the floats were too high), and dump fuel, causing raw fuel to get past the jets?Thanks for your imput.
I know about alcohol, but it is not running right,and that is more important,(to me), than the emission problem.Pump is there,and belted, and the exhaust, is all original, and good.We get less annual precipitation than the Sahara desert, and our average humidity is around 15 to 25 percent, so there is no rust to the exhaust system, and it is all tight.
Is it possible to foul the thermactor?It was grossly flooded, (probably for years), before I bought it.

trochoid

iTrader: (6)

Did you adjust the floats? That's generally a nono as they rarely, if ever, need changed. Fuel level should be dead center in both windows. There's even a notch in the side of each one to show where the level should be. You can take just the top of the carb off, (air horn), and check both floats for rise and drop. Be gentle with the adjustment, it doesn't take much.

Also set your idle at 750 rpm.

innertwist

iTrader: (3)

Reset the floats to where they should be - having them too high would make it run too rich, which could also explain the high end sluggishness. Also, like Trochoid said set, set the idle higher - it runs more efficient at higher rpms (assuming it's just an idle test). You can reset it to where you're more comfortable after emissions.

When you say thermactor, do you mean thermal reactor? They stopped using those after the 80' model. You should have a regular exhaust manifold/cat.

Kentetsu

That's what I was wondering too. When you rebuilt the carb, did you adjust the floats? Usually, if the carb was not having an issue with fuel levels before the rebuild, we would advise you to leave them alone. Far too easy to mess things up, and can be tough to get them right again.

A really good place to learn about the Nikki carb is Sterling's website www.sterlingmetalworks.com There are a lot of great articles and information there, along with a small carb specific forum. I learned a lot about carbs when I read those articles a few days ago, and I've been into my RX7 for nearly a decade. A pretty good resource, and if you post a question then you will get personal attention from Sterling himself...

But as for your specific issue here (high fuel levels), I just want to make sure of something. You stated that everything is stock, correct? Does that include the fuel pump? Sometimes people upgrade their fuel pump, but fail to install a pressure regulator, which results in the fuel pressure overpowering the carb.

If you did not adjust the floats when you rebuilt the carb, then it could be that they are hung up. Happens sometimes. If you did not adjust the floats, then you might try banging on the top of the carb with a plastic hammer or similar item to see if you can knock them loose. Best way is probably to go ahead and pull the top of the carb off again. Look closely at how the floats hang, and where they can get hung up. Also, a lot of guys recommend taking the finish off of the head on the float needles. New needles sometimes will stick, so they scrub them up lightly with a little bit of emery cloth or something. Just be sure you don't cause any damage to them, you just want to remove the finish on them.

Good luck....



.

DivinDriver

iTrader: (15)

If you do have a thermal reactor for some strange reason, no, it's not possible to foul it. If it's not cracked or ruptured internally, it's fine.

I'm still having flooding issues myself with my meticulously-rebuilt carb, which passed Cali smog, but later developed a tendency to near-flood (gouts of darkish fuel-smelling smoke) on restart, after shutoff & partial cooldown.

Still not sure what's causing it, but I think the odds are that the new needles are sticking a bit through thermal expansion after the cooling system shuts down and the carb heat-soaks. I'm hoping wear-in by the needles will eventually clear it up. Comes and goes.

Kentetsu

After you shut her down, pull off the air cleaner and see if you have fuel running into the carb. Perfect Circle went through something similar, it turned out that the restrictor in the return line was backwards.

Also, make sure the float bowl vent solenoid is hooked up and working correctly.

DivinDriver

iTrader: (15)

Good advice, thanks. Might actually have a chance to do so this weekend.

I'm sure my restrictor is in the right direction (it's labelled "carb" with an arrow...) but perhaps it's sticking.

Checked the vent solenoid when I rebuilt, but perhaps it (or it's signal) has given up since then.

I'll let you know how it turns out.

trochoid

iTrader: (6)

The 5 county Denver metro area does a running dyno for emissions, which maf, the op, lives in. Been there, done that in the FC when I first bought it. Won't pass now days though since I removed the air pump and installed the headers and an HKS pre-silencer.

When you tap the top of the carb, tap lightly on the banjo bolts that hold the fuel lines to the top of the air horn.