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Rebuilt my Nikki carb, it seems to be a 1979 carb, as far as I can tell. Got around to the accelerator pump circuit and there was only a weight and check ball in the outlet of the AP circuit. No check ball or weight above where the inlet is.
The only thing there was the screw below. Is it normal for any of the RX carbs to not have a weight and check ball above the inlet?
After rebuilding the carb and setting the idle, any sort of decent throttle input at idle makes the car fall on its face and spike lean on my wideband. Mashing the throttle above 2000ish RPMs and it does fine.
I don't recognize that "patina" looking brass screw thing you posted. And to answer your question, all Nikki carbs, from at least the twin dizzy
RX-2 1971-73 carbs up through the 1985 FB models had a check ball and brass weight. Sounds like your carb needs 'em.
Can you post more pics of your mystery setup please? Maybe the Nikki gurus here can help.
There's a thread with images that I started back when I got the car trying to identify what the carb was. The general consensus was that it was a 79 carb.
The issue at the time was that nowhere on the carb was there any sort of identification for it.
Hmm, that looks like a twin dizzy carb to me. I've got one and will check to see if mine has that weird brass screw thing or a check ball and weight type of screw.
Ok, I've looked at my carb and it seems to have a normal screw from the outside. I say this because I'm not wanting to unscrew the screw right now to look down below it for a weight ans checkball or lack there of.
Just for clarification, I'm talking about the screw located on the main body right above the accel pump housing. My screw is also not discolored greenish. It has a normal looking brass color.
What you have there is probably a really early carb, like a 1971 maybe. Is there any way to adjust the rod that pushes the accel pump lever? I see on your carb it has a cotter pin and a washer on the end.
It's a lovely museum piece, but if it offers poor drivability...
I'm sorry but I don't have quite enough experience on this vintage.
One possible thing to look at is the accel pump diaphragm itself. Is yours old and hard like a leather boot? Or soft and supple like nice driving gloves?
Fortunately it is a Nikki and might accept newer parts thrown at it... except for maybe the screw... But something tells me maybe a little bit of an adjustment for where it begins to squirt would help you here. Add a little bit of preload onto the diaphragm. I find this works well on finicky carb with the more common checkball and brass weight setups. you know, the 7mm nylock nut on the end of that rod that on yours has a cotter pin instead.
The cotter pin has three different holes that can be used. Before I disassembled the carb the pin was in the middle hole of the three holes, so that's where I put it back on reassembly.
The diaphragm that came out of the carb was almost indiscernible from the new one I put in from the Hygrade rebuild kit. Truly, the carb may not have even needed rebuilding with how clean and nice everything was on the inside.
As far as the screw goes it looks pretty similar to a 79-85 screw, minus the rod on the bottom, amd the rod doesn't have any holes in it as a jet would, so I'm not sure what purpose it serves exactly.
I decided to go back to this carb after fiddling with a DCOE for a while. Finally realizing that a Nikki carb should/would be my easiest/best option since I plan for this car to be my daily driver. I would really hate to buy another carb. Minus the lean stumble I mentioned, it seems pretty good.
ok I think I understand how the old setup is supposed to work. If it doesn't already have a checkball, add one.The rod is probably supposed to allow the checkball to lift up against it during fuel intake from the float bowl. That is my best guess.
Fantastic idea. I went back outside and pulled that screw again. It has a very slight, circular wear mark on the bottom of the rod that looks like what a check ball would do.
Well, I don't have a check ball, is there a general use hardware store type of replacement?
I looked around for the Hygrade kit with the check ***** in it and all I could find was the 1556 kit I already have. Checked O'Reilly's, AutoZone, Rock Auto, CarID, Walmart, even Mazdatrix and Atkins. All the same kit from the pictures, at least.
Can't find the hygrade kit with check ***** anywhere it seems. Is there a member on the forum that I could contact and purchase a check ball from, perhaps?
I checked around for GP Sorensen kits. They don't appear to have check ***** in the images at least. And for 50 dollars... Not quite ready to spend 50-60 dollars on something that may not even be what I need. I've done enough of that already. Hah.
Managed to source a check ball from another forum member. Installed it and the car starts with a couple of pumps of the pedal and no more lean spikes on quick throttle inputs. Perfect
05-26-20, 05:18 PM
Nikki Carb Accelerator Pump
