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-   -   Carburetor change? (https://www.rx7club.com/1st-gen-general-discussion-207/carburetor-change-1133451/)

Carter Dial 02-04-19 06:00 PM

Carburetor change?
 

https://cimg2.ibsrv.net/gimg/www.rx7...d4142fbc1.jpeg
So I have decided to scrap the original Nikki four barrel and was going to get a adapter plate milled and polished to go from the stock carb to a Holley 350 two barrel. Thoughts?

GSLSEforme 02-04-19 07:09 PM

Whatever problem the Nikki has,fix it and keep it. Cobbling a 2V Holley carb and adapter plate together is essentially going backwards both from a driveability and a performance standpoint. What is your purpose in going this route?
What's the story on the Dart in the background?

Carter Dial 02-04-19 08:23 PM


Originally Posted by GSLSEforme (Post 12328362)
Whatever problem the Nikki has,fix it and keep it. Cobbling a 2V Holley carb and adapter plate together is essentially going backwards both from a driveability and a performance standpoint. What is your purpose in going this route?
What's the story on the Dart in the background?

The dart is one of my co-workers. The Nikki is terrible to work on and a new one is very expensive to my budget. Which I am still debating just buying a new intake manifold that is made for a Holley carburetor instead. I just need something to get it running right now .

Qingdao 02-04-19 08:37 PM

I'm just trying to figure out how he's going to get a 2V carb to work on a 4 port manifold...…. :scratch:


But yeah, 100% backwards direction. And how do you figure its difficult to work on a nikki compared to a holley? And who is selling new Nikki four barrel carbs?


No no no this doesn't add up at all. I'm calling trolling; you had me going. :lol:

Qingdao 02-04-19 08:40 PM

But I would like to say if you do go with a 2 barrel carb keep us posted. That'll put my redneckery in check.

Carter Dial 02-04-19 08:54 PM


Originally Posted by Qingdao (Post 12328395)
But I would like to say if you do go with a 2 barrel carb keep us posted. That'll put my redneckery in check.

I went to a machine shop and he said he could milk me a aluminum adapter and port and polish it and there would be no flow reduction. He is cutting it on a water jet. Once I get it cut I will upload a picture

Carter Dial 02-04-19 08:57 PM


Originally Posted by Qingdao (Post 12328393)
I'm just trying to figure out how he's going to get a 2V carb to work on a 4 port manifold...…. :scratch:


But yeah, 100% backwards direction. And how do you figure its difficult to work on a nikki compared to a holley? And who is selling new Nikki four barrel carbs?


No no no this doesn't add up at all. I'm calling trolling; you had me going. :lol:

Also O’Reillys can specially order the stock Nikki carb but you have to cal to order it which leads me to believe its much more expensive than testing the two barrel out first.

GSLSEforme 02-04-19 09:49 PM

The O'Reillys carb will not be new,it will be a reman. I was not aware they sold or could even get reman Nikki carbs. I have no idea of the quality of them,or how long it would take to order one in. Since you find your Nikki hard to work on,either find someone to rebuild it for you or use yours as a core for the O'Reillys reman.The Nikki was designed for the rotary engine while the Holley,any Holley is not. Trying to make any 2V carb work on a rotary will be a futile effort.

Carter Dial 02-04-19 09:56 PM


https://cimg5.ibsrv.net/gimg/www.rx7...481bcc061.jpeg
https://cimg9.ibsrv.net/gimg/www.rx7...8448c5e9b.jpeg

Originally Posted by GSLSEforme (Post 12328415)
The O'Reillys carb will not be new,it will be a reman. I was not aware they sold or could even get reman Nikki carbs. I have no idea of the quality of them,or how long it would take to order one in. Since you find your Nikki hard to work on,either find someone to rebuild it for you or use yours as a core for the O'Reillys reman.The Nikki was designed for the rotary engine while the Holley,any Holley is not. Trying to make any 2V carb work on a rotary will be a futile effort.

What about the twin Weber carbs with the matching intake? I know those are some what pricy but would that be a better option?

KansasCityREPU 02-04-19 10:06 PM

Now the Weber is a much better choice. You'll want to add a header for the exhaust to make it come alive.

Carter Dial 02-04-19 10:09 PM

[QUOTE=KansasCityREPU;12328421]Now the Weber is a much better choice. You'll want to add a header for the exhaust to make it come alive.[/QUOTE

i have already added a pace setter header , and removed all the rats nest , thinking about putting a electric fan in too. Good idea ?

Qingdao 02-04-19 10:12 PM

Lots of guys go with webbers or IDA or other single throat carbs. That's pricy IMPO.

What's wrong with the nikki?

Before you toss it in the trash try unscrewing the 9 bolts that hold the top on (I'm just recalling that number from memory), and peek down inside. Take a can of carb cleaner with you and try not to mess with the floats (cause they are the devil to reset). Spray the carb cleaner down each of the little holes (they are the air bleeds). Then take the straw from the can of carb cleaner and stick it down in the fuel jets they are at the bottom of the v in the middle of the bowels on either side of the carb.

This process will dislodge most anything in the carb that will cause it to not deliver fuel at anything other than idle. Try this before you toss your hands up and let a simple carb kick your butt. ;)

The ONLY part of the Nikki that is a pain to work on is the idle circuit. Just because it is cast into the base plate, but it doesn't often get that clogged.

Carter Dial 02-04-19 10:21 PM


Originally Posted by Qingdao (Post 12328424)
Lots of guys go with webbers or IDA or other single throat carbs. That's pricy IMPO.

What's wrong with the nikki?

Before you toss it in the trash try unscrewing the 9 bolts that hold the top on (I'm just recalling that number from memory), and peek down inside. Take a can of carb cleaner with you and try not to mess with the floats (cause they are the devil to reset). Spray the carb cleaner down each of the little holes (they are the air bleeds). Then take the straw from the can of carb cleaner and stick it down in the fuel jets they are at the bottom of the v in the middle of the bowels on either side of the carb.

This process will dislodge most anything in the carb that will cause it to not deliver fuel at anything other than idle. Try this before you toss your hands up and let a simple carb kick your butt. ;)

The ONLY part of the Nikki that is a pain to work on is the idle circuit. Just because it is cast into the base plate, but it doesn't often get that clogged.

The thing is that the carb has been rebuilt with all new jets and new floats . The carb keeps flooding is the problem.

Qingdao 02-04-19 10:54 PM

Boom, there is your problem.

Your solution is to either put the old seats/floats and needles back in, or take the seats and needles out and burnish them.

The new kits (much like new Webber carbs and Holley carbs) are made cheaply quickly, and they have lots of rough edges. Smoothing the roughness off the new needles will make them not stick in the seats.

Carter Dial 02-05-19 07:21 AM


Originally Posted by Qingdao (Post 12328432)
Boom, there is your problem.

Your solution is to either put the old seats/floats and needles back in, or take the seats and needles out and burnish them.

The new kits (much like new Webber carbs and Holley carbs) are made cheaply quickly, and they have lots of rough edges. Smoothing the roughness off the new needles will make them not stick in the seats.

Okay I will try this and keep you guys updated later today.

t_g_farrell 02-05-19 09:58 AM


Originally Posted by Qingdao (Post 12328432)
Boom, there is your problem.

Your solution is to either put the old seats/floats and needles back in, or take the seats and needles out and burnish them.

The new kits (much like new Webber carbs and Holley carbs) are made cheaply quickly, and they have lots of rough edges. Smoothing the roughness off the new needles will make them not stick in the seats.

Right on! This is exactly your issue. Did you rebuild it or get it done or it came that way? Doesn't matter, do what was suggested. Also is it an OEM fuel pump or after market? The nikki only likes to see 2.5 psi max fuel pressure. That will cause flooding also.

Carter Dial 02-05-19 10:58 AM


https://cimg2.ibsrv.net/gimg/www.rx7...89b2f128d1.png
The OEM pumps kept taking a shit of me.

Originally Posted by t_g_farrell (Post 12328491)
Right on! This is exactly your issue. Did you rebuild it or get it done or it came that way? Doesn't matter, do what was suggested. Also is it an OEM fuel pump or after market? The nikki only likes to see 2.5 psi max fuel pressure. That will cause flooding also.

It has a micro edelbrock fuel pump and a fuel regulator .

Maxwedge 02-05-19 02:59 PM

Mine would flood at 3psi or higher, and stop flooding at a hair under 3 (literally a hair, like 2.9) Also, you mentioned removing the rat's nest. If you also cleaned up your wiring you want to keep an ignition-hot 12v on the Air Vent Solenoid plug. Without it you'll get flooding issues. Hard to see but I used some of the left-over wiring I stripped out and made a little 3-plug pigtail to plug inline with the temp sensor connectors.

https://cimg9.ibsrv.net/gimg/www.rx7...fe2ccb4f24.jpg
https://cimg5.ibsrv.net/gimg/www.rx7...4f01d5c9e8.jpg

DivinDriver 02-05-19 06:24 PM

Nothing at all wrong with a Nikki. Just have to learn them.

They're not complicated, for a carb.

Carter Dial 02-05-19 07:36 PM


Originally Posted by Maxwedge (Post 12328550)
Mine would flood at 3psi or higher, and stop flooding at a hair under 3 (literally a hair, like 2.9) Also, you mentioned removing the rat's nest. If you also cleaned up your wiring you want to keep an ignition-hot 12v on the Air Vent Solenoid plug. Without it you'll get flooding issues. Hard to see but I used some of the left-over wiring I stripped out and made a little 3-plug pigtail to plug inline with the temp sensor connectors.

https://cimg9.ibsrv.net/gimg/www.rx7...fe2ccb4f24.jpg
https://cimg5.ibsrv.net/gimg/www.rx7...4f01d5c9e8.jpg

Thank you for the advice, makes sense! But my air vent solenoid wire is completely gone. Also what fuel regulator do you suggest

Carter Dial 02-05-19 08:32 PM


Originally Posted by Maxwedge (Post 12328550)
Mine would flood at 3psi or higher, and stop flooding at a hair under 3 (literally a hair, like 2.9) Also, you mentioned removing the rat's nest. If you also cleaned up your wiring you want to keep an ignition-hot 12v on the Air Vent Solenoid plug. Without it you'll get flooding issues. Hard to see but I used some of the left-over wiring I stripped out and made a little 3-plug pigtail to plug inline with the temp sensor connectors.
Are these photos accurate

https://cimg8.ibsrv.net/gimg/www.rx7...1b6a9791e1.png
How accurate are these photos also?
https://cimg7.ibsrv.net/gimg/www.rx7...fa4257123f.png

https://cimg9.ibsrv.net/gimg/www.rx7...fe2ccb4f24.jpg
https://cimg5.ibsrv.net/gimg/www.rx7...4f01d5c9e8.jpg

how accurate are these photos

Maxwedge 02-05-19 09:02 PM

The photos are accurate, as in, that is my car. The notes on the Mazda pictures sound right. I used this guide for the stripping -
http://foxed.ca/rx-7/Carb%20Stripping%20Draft%201.pdf
The only parts to be careful with are -
*Removing the choke butterfly: Don't do it if you plan on ever starting the car below 55 Degrees F
*Goobering up the vacuum holes with JBWeld. Yuck! I made blockoff plates/gaskets for anything I opened up, so that I or the next owner can restore it to stock.
*Removing the Dashpot. Unlike an Edelbrock or Holley, the Nikki will stall you out if you stop short (mine did/does anyway). The stripping guide says to learn some finesse when stopping. Fuck that - you end up stalling in every intersection. Put the Dashpot back on and your fine again. That was my experience, YMMV.

If your Air Vent Solenoid wires are cut that is why you're flooding. ***Someone with more experience than me please chime in here.*** It's my understanding that if the car is running, that valve needs to be open for air/vapor/fuel flow to work right. It needs 12v to it to stay open. Cut the wires and it is stuck shut, which causes flooding. I think this part is still available and affordable.

Carter Dial 02-05-19 09:14 PM


Originally Posted by Maxwedge (Post 12328622)
The photos are accurate, as in, that is my car. The notes on the Mazda pictures sound right. I used this guide for the stripping -
http://foxed.ca/rx-7/Carb%20Stripping%20Draft%201.pdf
The only parts to be careful with are -
*Removing the choke butterfly: Don't do it if you plan on ever starting the car below 55 Degrees F
*Goobering up the vacuum holes with JBWeld. Yuck! I made blockoff plates/gaskets for anything I opened up, so that I or the next owner can restore it to stock.
*Removing the Dashpot. Unlike an Edelbrock or Holley, the Nikki will stall you out if you stop short (mine did/does anyway). The stripping guide says to learn some finesse when stopping. Fuck that - you end up stalling in every intersection. Put the Dashpot back on and your fine again. That was my experience, YMMV.

If your Air Vent Solenoid wires are cut that is why you're flooding. ***Someone with more experience than me please chime in here.*** It's my understanding that if the car is running, that valve needs to be open for air/vapor/fuel flow to work right. It needs 12v to it to stay open. Cut the wires and it is stuck shut, which causes flooding. I think this part is still available and affordable.

Thank you! Do you know where I could possibly find this air vent solenoid? Could I not just bypass that air vent by putting a short bolt in place leaving that passage way consistently open?

Maxwedge 02-05-19 10:13 PM

Try Atkins Rotary, Racing Beat, Google, Ebay, I don't know. One of the last sections in that stripping guide is about removing this, and it seems tricky. I took some better pictures of my OE/stripped/Sterling-modded intake and the pigtail I made for powering the vent solenoid. The last picture shows the water temp sensor plugs I connected to, to power the solenoid. These OE wires send the signal from the temp sensor to the choke knob, so your factory choke operates. It's hot with the ignition and right there, so I tapped into it. I never saw this done, so thought I'd post what I did. This last pic shows an Edelbrock carb (which I don't recommend) but shows where I get power for Eddy/Holley carb electric chokes. #1- factory plug in harness #2- Factory temp sensor plug #3 my wire to aftermarket electric chokes.

https://cimg0.ibsrv.net/gimg/www.rx7...65345c1bb9.jpg
https://cimg0.ibsrv.net/gimg/www.rx7...2bfcf2f4c3.jpg
https://cimg4.ibsrv.net/gimg/www.rx7...ea0e978074.jpg
For a Nikki you want 2.5 to 3psi (max). Not sure the best regulator to use, other than a stock pump and no regulator. I used / tried an NX low pressure regulator rated at 1.5 to 11 psi, but at 3psi the adjusting screw literally screwed out. I had to use Thread locker to hold it in one thread, so I don't recommend that brand.

Maxwedge 02-05-19 10:30 PM

Oh, I had to tap into the wiring because I removed a Lot of the OE wiring harness when I ditched the rat's nest. You may still have the correct plug in your car.

https://cimg5.ibsrv.net/gimg/www.rx7...ea998d5e9a.jpg
https://cimg7.ibsrv.net/gimg/www.rx7...972d59dae9.jpg
No wonder these cars are so heavy!


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