Being a young whipper snapper I havnt touched carbs really however the race car has the floats set a little high and I have no idea how to change it . So whats the easiest/best way to adjust the carb float levels? (Stock carbs except maybe having Grose jets)

 

Pretty much you need the carb manual for this. Its available at the sgt foxes website. Someone here can post a link. I just literally set mine yesterday. It is easy. there is a tiny metal flange at the end of the float, its called a tang. It needs to be bent VERY VERY gradually. Too much and it will break and you will cry. Bend it very little, then re install it. Measure the distance like the carb manual says. Configure it to match the manual

 

Seriously, the carb fsm is going to be the best instruction. Btw, if youre going top own a race car that is also an rx7 then you need to be really familiar with the nikki carb. Get to learning junior.

 

the float adjustments are also in the FSM. in order to adjust the float level, you need to remove the air horn (top of the carb) and measure each float adjustment before making any adjustments. in order to adjust the float properly you will need a new air horn gasket. there are two adjustments that must be made to each float to ensure it is at the proper height. if you would like i can post the specs on the float adjustment.

 

One of our foremost carb experts always exclaims "Leave yer darned floats alone!", and for very good reason. They don't just go out of adjustment, unless the carb has been dropped or something.

Why do you think that they need adjustment? Is the fuel level at the halfway mark in the float bowl windows?




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Much appreciated

On a street car I agree, never touch the floats however this isnt a street car. Due to what people previously thought was fuel boiling back before I got my car people would play with the floats/jets etc to try and get rid of it. Was later found out to be that in hard corners it was actully flooding the car and causing it to sputter which is solved by lowering the float level. As far as where its at now in the float bowls I dont even know where to look.

 

Before you do that, check this out. I run autocross, so I'm probably seeing greater G forces that you are on a track, and I have run accross exactly your issue. If you drop the float level, it may help a bit, but you will run the chance of running dry at higher sustained RPMs.

Here's how I addressed it, and several others have done the same with good results. Reduce your fuel pressure. That's it. And, as long as your jetting is correct and fuel filter/pump are good, you should still retain the top end performance.

What I do is find an empty parking lot, and start running counter clockwise until it bogs. Step the pressure down a tad, and repeat. Do this until I reach the point where it no longer bogs. Carb seems to perform perfectly in all other aspects at that fuel pressure.

Another option, which Sterling recommended to me before I found my solution, is to use an older style of float. He's been back on the forum recently, so shoot him a PM if interested.

Best of luck...

 

I dont want to hi jack, but its so related. I recently pulled a junkyard carb and rebuilt. The nikki floats were set way too low, so I set them to factory spec per the fsm. Should I have left them alone?

 

Floats can be tricky. If you have a vacuum pump and a new bowl gasket ready it is easy as pie to adjust. The pump is for sucking the fuel out of the bowls so the fuel pump can set your floats to their actual level after each adjustment. Just pour it in a gas can and back into your gas tank when your done so there is no wasted fuel. Good for jet changes too.

Just bend the littler stopper tab with a pair of needle nose plyers in tiny increments maybe 0.5mm? if i remember correctly in the upright position bending the tab down lowers your level and bending upward raises it. Replace, test, readjust if necessary. You may need a mirror and flash light to see the rear glass. It can look decieving without one.

Btw if your fuel pressure is too high it can overfill the bowls. And yes my sterling came with older floats. Maybe rx3 or something?

 

So another question. Related. And I dont want to start a new thread. If both bowls are over filling, and I adjusted floats to factory spec, how can I lower the float levels? Also, does the nikki need a pressure regulator? And what psi should it be set to?

 

The Nikki needs about 2 - 2.5 psi to run. If the pump you have is rated higher than that, then you need a regulator to reduce the pressure. This is very likely if the floats are properly adjusted and the bowls are overfilling (or the needles aren't seating).

 

Hmm... Going to burnish the needles. re check floats. Then whack a mole with a rubber mallet.

 

Sounds like a good plan.

 

the floats (on any carb) are tricky to adjust, because usually the factory measurement is not actually measuring the level of fuel in the bowl, and b it actually demands a lot of precision.

so it may be that half a millimeter in fuel level makes a big difference in the way the car runs, but we're not measuring the fuel level, we measure the distance between the float and the carb top (usually).

with the Nikki, the parts are really small (compared to a weber IDA) and the adjustment is usually right right out of the factory, its best to just leave it alone

 

I wish I could have...

 

its trial and error...

 

Go for early style floats if you can find them, I've heard from several people that these remove the cornering issues.

As for setting the float levels, I would be basing adjustments from the fuel level in the sight glass. The large centre tab is the important adjustment as it controls the position of the needle relative to the float (measured with the air horn upside down, the gap between the top of the float and the lip of the air horn). I've never really worried about the other tab (float drop) as long as they appear fairly close together (within a few mm).

If your floats are out after a rebuild, check that both seats have one washer where they screw into the air horn. It's easy to pull out the old seats and not realise there is a washer still stuck on there when installing new ones. Also the burnishing trick is a MUST to prevent flooding, but personally I use a razor edged knife to scrape the surface off the needle corners rather than Sterling's method.