Nikki running insanely rich
11-09-16, 05:03 PM
#27
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Glowing exhaust manifold!!!
Today i pulled the brake booster hose to make sure it was in good shape. I checked all the other hoses/vacuum lines/connections to make sure everything else was in good shape and there was nothing obvious I was missing. Then I tried starting it again. It felt more or less the same as the last couple days, it would only start with the no choke and the pedal on the floor -WOT.
The fact that it starts better with no choke even though it's 4 deg C/39 deg F seems odd to me.
I started it a couple times and it died seconds later each time, then all of a sudden it ran! I kept it running for a good 20-30 seconds. As soon as i realized it was going to keep running i tried working it through the range a bit, half to full throttle, to see how it felt. It was a very slow climb past 4500, and it basically wouldn't go past 5000. I let off the throttle a bit to see if it would idle, but it sputtered and died. I then noticed some smoke coming from under the hood. THE EXHAUST MANIFOLD WAS GLOWING BRIGHT ORANGE!!!
I think these exhaust temps indicate I'm either running very lean, or the timing is too retarded. I think I will pickup a timing gun to see if it's correct.
Based on my forum searches, the other possibilities are having the coils mixed up so they are firing the wrong side, or not having any spark on the leading plugs. I have checked these 2 things, but will double check to be sure.
I was really excited to have the car running for more than 10 seconds. -It's been a long time, or at least a lot of cranking, recharging, and repeating... I don't know if it's progress, but at least it's different
What do you guys think is the most probable cause with this new symptom?
The fact that it starts better with no choke even though it's 4 deg C/39 deg F seems odd to me.
I started it a couple times and it died seconds later each time, then all of a sudden it ran! I kept it running for a good 20-30 seconds. As soon as i realized it was going to keep running i tried working it through the range a bit, half to full throttle, to see how it felt. It was a very slow climb past 4500, and it basically wouldn't go past 5000. I let off the throttle a bit to see if it would idle, but it sputtered and died. I then noticed some smoke coming from under the hood. THE EXHAUST MANIFOLD WAS GLOWING BRIGHT ORANGE!!!
I think these exhaust temps indicate I'm either running very lean, or the timing is too retarded. I think I will pickup a timing gun to see if it's correct.
Based on my forum searches, the other possibilities are having the coils mixed up so they are firing the wrong side, or not having any spark on the leading plugs. I have checked these 2 things, but will double check to be sure.
I was really excited to have the car running for more than 10 seconds. -It's been a long time, or at least a lot of cranking, recharging, and repeating... I don't know if it's progress, but at least it's different
What do you guys think is the most probable cause with this new symptom?
11-10-16, 08:46 AM
#31
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I could send you the other carb I bought, you can have at it, then I'll compare the two to try and gain some insight. My wife just wants it to be fixed. I want to learn what the problem is and how to fix it. Do you think it's just the carb causing these issues?
11-10-16, 10:15 AM
#33
carb whisperer
engines dont just jump timing randomly, and it sounds to me like it's starving for fuel.
11-10-16, 11:11 AM
#34
Yes, but wankel=awesome you personally were not the one tinkering. I'd check timing. Lean does mean hot, but radioactive hot more likely means timing. If the exhaust was glowing like my headers pictured above; i'd buy timing as being a culprit.
11-10-16, 11:15 AM
#35
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I pulled the distributor out to test the igniters. I tried to be careful but I think it might have jumped a tooth when I reassembled it.
11-11-16, 05:55 PM
#36
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I reset the timing and it started up. It still will only start with the throttle open and choke off. I think it needs to be leaner, it runs much better without the choke on. It did run better than it has in a long time. I had to turn in the idle speed screw to get it to idle, lowest it will maintain is about 1100. This was the first time it has left my street in 3 months! I was soooo excited. It is totally drivable, but not totally enjoyable. I drove it to work and ran a couple errands today, over 1 hour of run time. So far so good.
I want it to run a lot smoother, it is really rough and jerky when coasting or maintaining a speed at low rpm.
I also want to fix it so the choke actually helps with cold starts, right now it makes it run worse in any scenario.
I want it to run a lot smoother, it is really rough and jerky when coasting or maintaining a speed at low rpm.
I also want to fix it so the choke actually helps with cold starts, right now it makes it run worse in any scenario.
11-27-16, 01:24 PM
#38
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The car runs great when under load. As long as the throttle is more than 1/8 open.
It will only start with the choke all the way in(no choke -wide open). To start it, I have to pump the pedal before starting(3 pumps for +15 deg C, 5 pumps 7-14 deg C, 8 pumps 0-6 deg C). Then I keep the pedal slightly depressed to keep it revving around 2500rpm and gradually decrease it as it warms up(2-5mins depending on outside temp) until it idles steady 1100-1300rpm. At this point it is driveable but will not cruise smoothly under 3000rpm at a steady speed under 80km/h. It has a strong bucking or surging feeling trying to keep a steady speed.
I think I have been pretty thorough in looking for a vacuum leak. Here is what I did:
I inspected all the hoses for visual signs of cracks or wear. I got the car warmed up to a point where it would idle at about 1200rpm, without me keeping the pedal depressed to keep the rpm up so it wouldn't die. I used a propane bottle with a hose to trace all around the carb, intake, and vacuum lines, but didn't find anything that affected how the engine was running. Then I pulled the choke out halfway so that it was coughing/popping(pulling it any further out, it will just die) and clamped it there to perform the same propane test looking for a vacuum leak.
The fact that I have to pump the accelerator, makes me think it's lean when starting, but the fact that it won't start with choke on, sounds like it's rich.
As far as I can tell, increasing the choke makes it run worse or die in any scenario.
If I installed a wideband O2 sensor and AFR gauge I could see what the fuel ratio is in different conditions, but it probably wouldn't help with starting unless it's directly related to another issue.
Should I crack open the carb again to look at the primary fuel circuits? Or keep looking for vacuum leaks? Or any other suggestions -open to any ideas here...
It will only start with the choke all the way in(no choke -wide open). To start it, I have to pump the pedal before starting(3 pumps for +15 deg C, 5 pumps 7-14 deg C, 8 pumps 0-6 deg C). Then I keep the pedal slightly depressed to keep it revving around 2500rpm and gradually decrease it as it warms up(2-5mins depending on outside temp) until it idles steady 1100-1300rpm. At this point it is driveable but will not cruise smoothly under 3000rpm at a steady speed under 80km/h. It has a strong bucking or surging feeling trying to keep a steady speed.
I think I have been pretty thorough in looking for a vacuum leak. Here is what I did:
I inspected all the hoses for visual signs of cracks or wear. I got the car warmed up to a point where it would idle at about 1200rpm, without me keeping the pedal depressed to keep the rpm up so it wouldn't die. I used a propane bottle with a hose to trace all around the carb, intake, and vacuum lines, but didn't find anything that affected how the engine was running. Then I pulled the choke out halfway so that it was coughing/popping(pulling it any further out, it will just die) and clamped it there to perform the same propane test looking for a vacuum leak.
The fact that I have to pump the accelerator, makes me think it's lean when starting, but the fact that it won't start with choke on, sounds like it's rich.
As far as I can tell, increasing the choke makes it run worse or die in any scenario.
If I installed a wideband O2 sensor and AFR gauge I could see what the fuel ratio is in different conditions, but it probably wouldn't help with starting unless it's directly related to another issue.
Should I crack open the carb again to look at the primary fuel circuits? Or keep looking for vacuum leaks? Or any other suggestions -open to any ideas here...
11-27-16, 02:31 PM
#39
Sounds like you need to get to the bottom of your issues. I personally would never run a stock Nikki due to their factory-induced problems. They have issues caused by idle air bleeds that are so big they let in so much air they will only work well on a fully warmed up engine when the choke flap is fully open. The idle air bleeds can be replaced with smaller ones which can allow the engine to run a ton better over-all and especially when cold, but if you use the choke flap there is a tendency to go pig-rich and brap on you. But you are already kind of experiencing this. A wideband is an extremely good idea. You will wonder how you ever played with carbs before you had one.
I've been all over the Nikki to figure out what they needed to make them run better in all conditions and even handle boost while also being hogged out bigger than a sane person would normally go. The only way these carbs will even run like this is by paying careful attention to the air bleeds. They're the key; air control. The fuel jets are almost an afterthought. It's all about dealing with the unwanted air through the circuits by going as small as you can until it starts to brap (or run unsmoothly), then going one step bigger.
Hey, that's kinda how to tune the fuel jets in carbs too. Find the perfect tune, then go one step bigger for safety.
I've been all over the Nikki to figure out what they needed to make them run better in all conditions and even handle boost while also being hogged out bigger than a sane person would normally go. The only way these carbs will even run like this is by paying careful attention to the air bleeds. They're the key; air control. The fuel jets are almost an afterthought. It's all about dealing with the unwanted air through the circuits by going as small as you can until it starts to brap (or run unsmoothly), then going one step bigger.
Hey, that's kinda how to tune the fuel jets in carbs too. Find the perfect tune, then go one step bigger for safety.
Last edited by Jeff20B; 11-27-16 at 03:31 PM.
11-27-16, 04:54 PM
#40
I've never heard of using a propane torch to look for a leak. Seems reasonable, but I've never done it.
I use carb cleaner. Or brake cleaner. I like it because you can pool it up around a possible bad gasket. The pool will suck in under vacuum and you get a solid conformation of a leak. Others will argue that brake cleaner/carb cleaner is too harsh or explosive. To the nei sayers I say if the gasket can't hold up to carb/brake cleaner I don't want that gasket on my car anyway.
My car is bitchy when its cold too. My other 7 was bitchy when cold as well it had a big American 4 barrel carb. I think its just a rotary trait.
I use carb cleaner. Or brake cleaner. I like it because you can pool it up around a possible bad gasket. The pool will suck in under vacuum and you get a solid conformation of a leak. Others will argue that brake cleaner/carb cleaner is too harsh or explosive. To the nei sayers I say if the gasket can't hold up to carb/brake cleaner I don't want that gasket on my car anyway.
My car is bitchy when its cold too. My other 7 was bitchy when cold as well it had a big American 4 barrel carb. I think its just a rotary trait.
11-27-16, 08:25 PM
#41
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Sorry Jeff20B, I'm a bit confused. It sounds like you're suggesting going to smaller air bleeds, -that should richen the mixture by restricting air-is that not what essentially what the choke does.The choke normally richens the mixture to compensate for denser cold air, are you recommending removing the choke? You also indicate that the "pig-rich brap" indicates the air bleeds are at the small limit, and they should be one size larger. Why do I need to pump the pedal to get the car started, then using the choke seems to indicate it's already too rich. I think I'm learning, just trying not to get confused.
I understand that trouble shooting carbs is complicated, diagnosing them is not as simple as 1+2=3. Feel free to keep feeding me with info.
I understand that trouble shooting carbs is complicated, diagnosing them is not as simple as 1+2=3. Feel free to keep feeding me with info.
Sounds like you need to get to the bottom of your issues. I personally would never run a stock Nikki due to their factory-induced problems. They have issues caused by idle air bleeds that are so big they let in so much air they will only work well on a fully warmed up engine when the choke flap is fully open. The idle air bleeds can be replaced with smaller ones which can allow the engine to run a ton better over-all and especially when cold, but if you use the choke flap there is a tendency to go pig-rich and brap on you. But you are already kind of experiencing this. A wideband is an extremely good idea. You will wonder how you ever played with carbs before you had one.
I've been all over the Nikki to figure out what they needed to make them run better in all conditions and even handle boost while also being hogged out bigger than a sane person would normally go. The only way these carbs will even run like this is by paying careful attention to the air bleeds. They're the key; air control. The fuel jets are almost an afterthought. It's all about dealing with the unwanted air through the circuits by going as small as you can until it starts to brap (or run unsmoothly), then going one step bigger.
Hey, that's kinda how to tune the fuel jets in carbs too. Find the perfect tune, then go one step bigger for safety.
I've been all over the Nikki to figure out what they needed to make them run better in all conditions and even handle boost while also being hogged out bigger than a sane person would normally go. The only way these carbs will even run like this is by paying careful attention to the air bleeds. They're the key; air control. The fuel jets are almost an afterthought. It's all about dealing with the unwanted air through the circuits by going as small as you can until it starts to brap (or run unsmoothly), then going one step bigger.
Hey, that's kinda how to tune the fuel jets in carbs too. Find the perfect tune, then go one step bigger for safety.
11-27-16, 08:51 PM
#42
The choke flap enforces a limited air supply, and it creates a stronger vacuum to pull more aif/fuel mixture out of the carb at lower RPM. As such, the air bleeds have to be pretty big to work properly with that. IT was designed ot work with stock 20MM venturis and on a stock ported 12A with a stock restrictive exhaust.
As soon as you start trying extract more power out of a Nikki, either by porting the engine or adding a free flowing exhaust, or even hogging out the Nikki's venturis, you need to throw the factory air bleed tune out the window and start over. This is when it is better to defer to others experiences, but not all the time. Other people who made a name for themselves regarding Nikki mods such as Yaw and Sterling, never quite got their heads wrapped around the air bleed issues these carbs have, which must be addressed if you want a carb that will run right all the time vs a finicky nightmare that must be tuned for a specific elevation,temperature and humidity. Yes!
Well to that I said no thanks. There was no way a Yaw or Sterling air bleed tune could come anywhere near close for boost let alone NA. But if you read the volumes they've written on the subject of tuning these carbs you'd beg to differ. Well, I'll just say that my carbs run fine NA and boosted. Theirs barely ran ok for NA and simply can not do boost at all. The secret, which isn't really a secret, are the air bleeds.
About a year ago I had the chance to work on a genuine Yaw carb and it was pretty terrible. It was only slightly better than the worst carb I have ever worked on, which was built by that stupid SVT guy who ripped off a lot of people here with carbs that didn't even run. Everything SVT touched needed to be fixed. By contrast, only most of what Yaw touched had to be fixed. I still have not had the chance to fix a Sterling carb but I bet it would be interesting. I'd succeed where Sterling failed in producing a boost prepped Sterling carb lol. Even if the owner doesn't need it to handle boost it doesn't matter because my carbs are universal and handle boost and NA equally just fine. There are some outliers that the carbs I've built don't run that well for them, but they did pass the test on my personal engine so I have to assume something ain't quite right on their car. I mean you gotta cover your *** sometimes, right? As such I don't build carbs for others anymore.
I don't want to confuse you further. Anyway, rotaries like a rich mixture when cold. Pretty simple.
As soon as you start trying extract more power out of a Nikki, either by porting the engine or adding a free flowing exhaust, or even hogging out the Nikki's venturis, you need to throw the factory air bleed tune out the window and start over. This is when it is better to defer to others experiences, but not all the time. Other people who made a name for themselves regarding Nikki mods such as Yaw and Sterling, never quite got their heads wrapped around the air bleed issues these carbs have, which must be addressed if you want a carb that will run right all the time vs a finicky nightmare that must be tuned for a specific elevation,temperature and humidity. Yes!
Well to that I said no thanks. There was no way a Yaw or Sterling air bleed tune could come anywhere near close for boost let alone NA. But if you read the volumes they've written on the subject of tuning these carbs you'd beg to differ. Well, I'll just say that my carbs run fine NA and boosted. Theirs barely ran ok for NA and simply can not do boost at all. The secret, which isn't really a secret, are the air bleeds.
About a year ago I had the chance to work on a genuine Yaw carb and it was pretty terrible. It was only slightly better than the worst carb I have ever worked on, which was built by that stupid SVT guy who ripped off a lot of people here with carbs that didn't even run. Everything SVT touched needed to be fixed. By contrast, only most of what Yaw touched had to be fixed. I still have not had the chance to fix a Sterling carb but I bet it would be interesting. I'd succeed where Sterling failed in producing a boost prepped Sterling carb lol. Even if the owner doesn't need it to handle boost it doesn't matter because my carbs are universal and handle boost and NA equally just fine. There are some outliers that the carbs I've built don't run that well for them, but they did pass the test on my personal engine so I have to assume something ain't quite right on their car. I mean you gotta cover your *** sometimes, right? As such I don't build carbs for others anymore.
I don't want to confuse you further. Anyway, rotaries like a rich mixture when cold. Pretty simple.
11-27-16, 09:41 PM
#44
There is a better way to tune 
Follow my advice.
idle air bleeds: 118 to 124
transition bleeds: 46 (stock)
primary main air bleeds: 70 (stock)
secondary main air bleeds: 80
secondary transition bleeds: solder filled upper tube only. Leave lower holes open.
nickel plated anti-siphon bleeds: 60 (stock)
That is my boost and NA air bleed tune which is universal.
Fuel jets depend on the size of your venturis and what your wideband tells you.
Idle: 12.2
part throttle primary cruise from 10 to 13
full throttle boosted 11.5
full throttle NA 12.5
However both NA and boosted can have the same full throttle tune at 11.5 with no ill effects. Just never go leaner than 11.5 when boosting.
Follow my advice.
idle air bleeds: 118 to 124
transition bleeds: 46 (stock)
primary main air bleeds: 70 (stock)
secondary main air bleeds: 80
secondary transition bleeds: solder filled upper tube only. Leave lower holes open.
nickel plated anti-siphon bleeds: 60 (stock)
That is my boost and NA air bleed tune which is universal.
Fuel jets depend on the size of your venturis and what your wideband tells you.
Idle: 12.2
part throttle primary cruise from 10 to 13
full throttle boosted 11.5
full throttle NA 12.5
However both NA and boosted can have the same full throttle tune at 11.5 with no ill effects. Just never go leaner than 11.5 when boosting.
11-27-16, 10:56 PM
#45
I just noticed you have an 84 car. Does your Nikki have a richer solenoid? If so, unplug it. It is the solenoid on the secondary side of the carb between the barrels. It could be influencing things if it is getting power while you are testing/diagnosing.
11-28-16, 07:46 AM
#46
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It does have the Richer solenoid. I will try unplugging it.
If that doesn't yield significant improvements, i will be looking at getting a wide-band O2 gauge and going with the jets and airbleeds you suggested.
I had an Innovate LC-2 wideband in my last car. I wish I pullled it out of the car. Maybe the new owner will sell it back to me, I doubt he knows what it is. LOL
If that doesn't yield significant improvements, i will be looking at getting a wide-band O2 gauge and going with the jets and airbleeds you suggested.
I had an Innovate LC-2 wideband in my last car. I wish I pullled it out of the car. Maybe the new owner will sell it back to me, I doubt he knows what it is. LOL
11-28-16, 11:24 AM
#47
You're stepping into a world of not always easy but very rewarding carb work. The Nikki is not a particularly easy carb to work on, but as it reveals its secrets to you, the experience can be quite profound and rewarding.
There is hidden performance in these carbs which only a few of us have learned how to unlock properly. But, following my advice which I've freely posted on the forum, others have unlocked their carbs and were quite impressed that they perform better than RB's Holleys which were the bog-standard in 4bbl carbs for rotaries. And I do emphasize the word bog.
Wankel=awesome's experience springs to mind. He has a lot of experience with Holleys and carbs in general, but built a Nikki with info I posted, and it's the best carb he has ever used on any rotary. His carb's specs are 24.5mm primary venturis and 28mm secondaries, both with 7/11 degree angle cuts in the venturis. His engine is a stockported 12A with RB's long primary exhaust and their spun aluminum air cleaner assembly. He is still working out his ignition but he'll eventually get it right. I recommend direct fire of course. If you start out with these basic necessities, your FB will perform so well you will wonder why it never came from the factory like this. You'll also realize it's better than a lot of newer and brand new EFI cars. Instead of a group of bean counters and engineers compromising on what they'd consider acceptable performance for the masses on all these newer bland as can be cars, you can tune your carb for your area and engine, driving style etc. It's pretty amazing.
We know how to make these cars and carbs perform. There aren't any secrets anymore. But you do need to learn as much info as you can. I recommend reading a lot. And then a lot more. And then keep on reading. A lot.
There is hidden performance in these carbs which only a few of us have learned how to unlock properly. But, following my advice which I've freely posted on the forum, others have unlocked their carbs and were quite impressed that they perform better than RB's Holleys which were the bog-standard in 4bbl carbs for rotaries. And I do emphasize the word bog.
Wankel=awesome's experience springs to mind. He has a lot of experience with Holleys and carbs in general, but built a Nikki with info I posted, and it's the best carb he has ever used on any rotary. His carb's specs are 24.5mm primary venturis and 28mm secondaries, both with 7/11 degree angle cuts in the venturis. His engine is a stockported 12A with RB's long primary exhaust and their spun aluminum air cleaner assembly. He is still working out his ignition but he'll eventually get it right. I recommend direct fire of course.
If you start out with these basic necessities, your FB will perform so well you will wonder why it never came from the factory like this. You'll also realize it's better than a lot of newer and brand new EFI cars. Instead of a group of bean counters and engineers compromising on what they'd consider acceptable performance for the masses on all these newer bland as can be cars, you can tune your carb for your area and engine, driving style etc. It's pretty amazing.We know how to make these cars and carbs perform. There aren't any secrets anymore. But you do need to learn as much info as you can. I recommend reading a lot. And then a lot more. And then keep on reading. A lot.
12-06-16, 01:15 PM
#49
carb whisperer
What Jeff said^^ The Nikki is literally unbeatable unless you go EFI, and it's really up for debate that an injected 12a is "better" than a carbed one.
follow the specs Jeff just gave you for my carb, and it will be perfect with no fiddling besides setting your idle.
follow the specs Jeff just gave you for my carb, and it will be perfect with no fiddling besides setting your idle.