Carburetor
09-28-19, 02:30 PM
#2
first off, welcome to the forum.
there are no "replacement" carbs for rotaries. either clean/rebuild the stock unit or go with aftermarket such as weber, delorto, or holley. but this will also mean changing out the intake. you can check racingbeat.com or mazdatrix.com. once you get the 10 post min requirement, you can check out the classifieds section. there's always someone selling these setups.
there are no "replacement" carbs for rotaries. either clean/rebuild the stock unit or go with aftermarket such as weber, delorto, or holley. but this will also mean changing out the intake. you can check racingbeat.com or mazdatrix.com. once you get the 10 post min requirement, you can check out the classifieds section. there's always someone selling these setups.
10-23-19, 06:04 AM
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Hi!
I just checked both. It is O'Reilleys and it costs $ 650 plus a core charge of $ 25.
We just had a bad experience with an Ebay rebuilder but sorted it out in the end. They rebuilt the carb and we got it back but it flooded so we sent it back, got it back and it flooded again.
In the end we took the top off this Sunday and it turned out they had adjusted one float to the correct 16mm, the other one to 8mm and that flooded the engine. Once we corrected this the car fired right up and the carb seems to run fine.
The rebuilt cost was $ 350 and can be found on Ebay but mostly for later models. We asked the seller if they'd do our 79 one as well and they agreed. So if you are aware things like misaligned floats can happen you might want to try that route. I assume in general they probably do correct rebuilds and we were just unlucky.
I just checked both. It is O'Reilleys and it costs $ 650 plus a core charge of $ 25.
We just had a bad experience with an Ebay rebuilder but sorted it out in the end. They rebuilt the carb and we got it back but it flooded so we sent it back, got it back and it flooded again.
In the end we took the top off this Sunday and it turned out they had adjusted one float to the correct 16mm, the other one to 8mm and that flooded the engine. Once we corrected this the car fired right up and the carb seems to run fine.
The rebuilt cost was $ 350 and can be found on Ebay but mostly for later models. We asked the seller if they'd do our 79 one as well and they agreed. So if you are aware things like misaligned floats can happen you might want to try that route. I assume in general they probably do correct rebuilds and we were just unlucky.
01-12-20, 08:33 PM
#7
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Vacuum lines
Is there any certain vacuum lines you HAVE to hook up to your carburetor on an 81 niki to get it to idle? I’ve rebuilt it and set all the floats correctly but it after it cranks for a few seconds it stalls out. I have also rebuilt the accelerator pump on it.
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01-13-20, 08:56 AM
#8
01-13-20, 05:08 PM
#9
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are these clear enough to see? It’s not bolted down I haven’t had the chance ever since I rebuilt it yesterday
01-13-20, 05:40 PM
#10
Waffles - hmmm good
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So you want to keep the rats nest and all the attendant stuff that comes on a stock carb right?
If thats the case you need to have the FSM and there are digital copies here with vacuum diagrams for each year. Hope this helps.
If thats the case you need to have the FSM and there are digital copies here with vacuum diagrams for each year. Hope this helps.
01-13-20, 05:51 PM
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So you want to keep the rats nest and all the attendant stuff that comes on a stock carb right?
If thats the case you need to have the FSM and there are digital copies here with vacuum diagrams for each year. Hope this helps.
If thats the case you need to have the FSM and there are digital copies here with vacuum diagrams for each year. Hope this helps.
01-14-20, 10:54 AM
#12
3D Printed
These carbs can be pretty far stripped down, but it depends on what you're looking to do. With your current vacuum line situation you are going to have a good number of leaks. Safest bet is to cap any vacuum nipple on the carb/phenolic spacer that does not have a line connected. Really you're best bet for figuring out what goes where is by looking at the appropriate year fsm diagram as tg_farrel said.
Currently your biggest leak with be the middle two vacuum lines in your first photo. The left middle provides the vacuum signal for the idle compensator and I believe also the pcv, not certain about that though. It sees vacuum at idle and will make tuning properly impossible. The right middle I believe runs to the pcv as well and should see vacuum at part throttle if I remember correctly.
If you're going to delete the nest the biggest thing you have to decide is what to do about a pcv. Your filler neck needs to be vented (preferably to a limited manifold vacuum source) to prevent moisture build up.
After that you also need to decide about your vacuum advance. I would suggest keeping it as it generally helps with low rpm power/better cruising mileage). You can easily run a vacuum line straight off the 2nd from front (or left side if looking from the drivers fender) nipple on the phenolic spacer and then teeing that to each vacuum pot on the dizzy.
If you don't know the current vacuum rack situation and just want to get running (albeit perhaps not optimally) your safest bet is to plug/cap all vacuum nipples on the phenolic spacer and carb that do not currently run somewhere. Beware of cheap vacuum caps though. The ones you often find at parts stores are poor quality and will quickly disintegrate leaving you with vacuum leaks once again. Many people here use the OEM ones off the rats nest because they are sturdy and last practically forever.
I would still suggest looking into things as opposed to just capping everything, but that option is there for you. It is almost guaranteed that the carb will not operate correctly if nipples are left open. There are some exceptions for certain carbs, but it's not consistent across all of them.
Hope that helps some.
Currently your biggest leak with be the middle two vacuum lines in your first photo. The left middle provides the vacuum signal for the idle compensator and I believe also the pcv, not certain about that though. It sees vacuum at idle and will make tuning properly impossible. The right middle I believe runs to the pcv as well and should see vacuum at part throttle if I remember correctly.
If you're going to delete the nest the biggest thing you have to decide is what to do about a pcv. Your filler neck needs to be vented (preferably to a limited manifold vacuum source) to prevent moisture build up.
After that you also need to decide about your vacuum advance. I would suggest keeping it as it generally helps with low rpm power/better cruising mileage). You can easily run a vacuum line straight off the 2nd from front (or left side if looking from the drivers fender) nipple on the phenolic spacer and then teeing that to each vacuum pot on the dizzy.
If you don't know the current vacuum rack situation and just want to get running (albeit perhaps not optimally) your safest bet is to plug/cap all vacuum nipples on the phenolic spacer and carb that do not currently run somewhere. Beware of cheap vacuum caps though. The ones you often find at parts stores are poor quality and will quickly disintegrate leaving you with vacuum leaks once again. Many people here use the OEM ones off the rats nest because they are sturdy and last practically forever.
I would still suggest looking into things as opposed to just capping everything, but that option is there for you. It is almost guaranteed that the carb will not operate correctly if nipples are left open. There are some exceptions for certain carbs, but it's not consistent across all of them.
Hope that helps some.
Last edited by Benjamin4456; 01-14-20 at 11:00 AM.
01-14-20, 12:46 PM
#13
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These carbs can be pretty far stripped down, but it depends on what you're looking to do. With your current vacuum line situation you are going to have a good number of leaks. Safest bet is to cap any vacuum nipple on the carb/phenolic spacer that does not have a line connected. Really you're best bet for figuring out what goes where is by looking at the appropriate year fsm diagram as tg_farrel said.
Currently your biggest leak with be the middle two vacuum lines in your first photo. The left middle provides the vacuum signal for the idle compensator and I believe also the pcv, not certain about that though. It sees vacuum at idle and will make tuning properly impossible. The right middle I believe runs to the pcv as well and should see vacuum at part throttle if I remember correctly.
If you're going to delete the nest the biggest thing you have to decide is what to do about a pcv. Your filler neck needs to be vented (preferably to a limited manifold vacuum source) to prevent moisture build up.
After that you also need to decide about your vacuum advance. I would suggest keeping it as it generally helps with low rpm power/better cruising mileage). You can easily run a vacuum line straight off the 2nd from front (or left side if looking from the drivers fender) nipple on the phenolic spacer and then teeing that to each vacuum pot on the dizzy.
If you don't know the current vacuum rack situation and just want to get running (albeit perhaps not optimally) your safest bet is to plug/cap all vacuum nipples on the phenolic spacer and carb that do not currently run somewhere. Beware of cheap vacuum caps though. The ones you often find at parts stores are poor quality and will quickly disintegrate leaving you with vacuum leaks once again. Many people here use the OEM ones off the rats nest because they are sturdy and last practically forever.
I would still suggest looking into things as opposed to just capping everything, but that option is there for you. It is almost guaranteed that the carb will not operate correctly if nipples are left open. There are some exceptions for certain carbs, but it's not consistent across all of them.
Hope that helps some.
Currently your biggest leak with be the middle two vacuum lines in your first photo. The left middle provides the vacuum signal for the idle compensator and I believe also the pcv, not certain about that though. It sees vacuum at idle and will make tuning properly impossible. The right middle I believe runs to the pcv as well and should see vacuum at part throttle if I remember correctly.
If you're going to delete the nest the biggest thing you have to decide is what to do about a pcv. Your filler neck needs to be vented (preferably to a limited manifold vacuum source) to prevent moisture build up.
After that you also need to decide about your vacuum advance. I would suggest keeping it as it generally helps with low rpm power/better cruising mileage). You can easily run a vacuum line straight off the 2nd from front (or left side if looking from the drivers fender) nipple on the phenolic spacer and then teeing that to each vacuum pot on the dizzy.
If you don't know the current vacuum rack situation and just want to get running (albeit perhaps not optimally) your safest bet is to plug/cap all vacuum nipples on the phenolic spacer and carb that do not currently run somewhere. Beware of cheap vacuum caps though. The ones you often find at parts stores are poor quality and will quickly disintegrate leaving you with vacuum leaks once again. Many people here use the OEM ones off the rats nest because they are sturdy and last practically forever.
I would still suggest looking into things as opposed to just capping everything, but that option is there for you. It is almost guaranteed that the carb will not operate correctly if nipples are left open. There are some exceptions for certain carbs, but it's not consistent across all of them.
Hope that helps some.
01-25-20, 02:30 PM
#14
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So I now have another carburetor noob question.... what are the possible issues if my car idles very well at 900-1000 but when I go to accelerate slowly my car stalls immediately but when I step on the gas and pulse it more forcefully it revs up fine?
01-25-20, 03:28 PM
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It shoots one steady pulse of fuel into the carburetor whenever I work the accelerator pump, is it supposed to be a constant stream or stop after the first initial pulse
01-25-20, 04:39 PM
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I got it to come out in both barrels but it doesn’t continuously shoot out as I hold the throttle, could that be the but not being in the right position where it’s linked to the main throttle?
01-25-20, 09:44 PM
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okay yeah I’ve got it to do that and it’s only stalling when I slowly press the throttle half of the time now, is the accelerator pump sensitive to that nut holding the spring in a sense that if I have it too far down condensing the spring too much or vise versa it will effect the accelerator pumps performance?
01-27-20, 12:55 PM
#22
84SE-EGI helpy-helperton
Think of the Accelerator Pump like a squirt gun. As long as you keep pulling the trigger, it's squirting water. In this example, as long as your foot is applying increasing pressure to the gas pedal, the Accelerator Pump is squirting a stream of extra fuel into the carb throat,... or it should be.
This extra squirt of fuel under acceleration helps to get the engine running rich enough to coincide with the advanced timing of your spark plugs firing to speed the engine up, and in turn speed the car up.
What you're describing about having to pump the gas pedal repeatedly to keep it running implies to me that you have insufficient fuel flow to the carb. Rationale being - the Accelerator Pump is fed by the incoming fuel flow but is stored in the Pump until you need it. The Float Bowls on the carb are fed - and drained - by the fuel supply flowing past the Needle Valves in their Seats. If the Needle Valves and Seats aren't sealed properly, you get flooding. If the Needle Valves and Seats are stuck, you get starvation. If your fuel flow is insufficient to fill the Float Bowls, you get starvation. My guess is your Accelerator Pump can keep the engine running with a mixture that will burn only when you're pumping it like a squirt gun - because doing anything beyond an idle is trying desperately to get more fuel into the air flow, but can't.
Focus on testing your fuel flow,
This extra squirt of fuel under acceleration helps to get the engine running rich enough to coincide with the advanced timing of your spark plugs firing to speed the engine up, and in turn speed the car up.
What you're describing about having to pump the gas pedal repeatedly to keep it running implies to me that you have insufficient fuel flow to the carb. Rationale being - the Accelerator Pump is fed by the incoming fuel flow but is stored in the Pump until you need it. The Float Bowls on the carb are fed - and drained - by the fuel supply flowing past the Needle Valves in their Seats. If the Needle Valves and Seats aren't sealed properly, you get flooding. If the Needle Valves and Seats are stuck, you get starvation. If your fuel flow is insufficient to fill the Float Bowls, you get starvation. My guess is your Accelerator Pump can keep the engine running with a mixture that will burn only when you're pumping it like a squirt gun - because doing anything beyond an idle is trying desperately to get more fuel into the air flow, but can't.
Focus on testing your fuel flow,
03-03-20, 08:09 PM
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Engine
So this is off the carburetor topic but it may still be linked.
I got the urge to test my rotors to see if they both are still getting good compression giving that I pulled the car from being parked for 27 years...
With the engine running, when I pull the spark plug wires on the front rotor of the engine it continues running, there seems to be some loss of power.
when I pull the back two spark plug wires on the rear rotor the engine stalls Immediately after pulling the second plug. (This is with the front two plug wires reinstalled)
so I began to think that the front rotor may have blown apex seals so I removed the rear spark plugs and tried to crank the engine on just the front rotor. After some starter fluid the engine cranked and began to idle on just the front rotor after 4 or 5 turnovers...
Can anyone explain this to me? The fact that I got both rotors to run by themselves confuses me since I couldn’t get the front rotor to run by itself when I removed the rear plug wires while the engine was already running.
sorry if it’s confusing this was the best way I could get it across.
I got the urge to test my rotors to see if they both are still getting good compression giving that I pulled the car from being parked for 27 years...
With the engine running, when I pull the spark plug wires on the front rotor of the engine it continues running, there seems to be some loss of power.
when I pull the back two spark plug wires on the rear rotor the engine stalls Immediately after pulling the second plug. (This is with the front two plug wires reinstalled)
so I began to think that the front rotor may have blown apex seals so I removed the rear spark plugs and tried to crank the engine on just the front rotor. After some starter fluid the engine cranked and began to idle on just the front rotor after 4 or 5 turnovers...
Can anyone explain this to me? The fact that I got both rotors to run by themselves confuses me since I couldn’t get the front rotor to run by itself when I removed the rear plug wires while the engine was already running.
sorry if it’s confusing this was the best way I could get it across.
03-03-20, 10:29 PM
#24
Notice any misfires at idle? If not; don't think about it. If you do have a misfire; compression test it and stop worrying. Worrying will only shorten your enjoyment of the engine. Send it.
To answer the question a dozen and a half things can lead to this. Poor fuel delivery on that side of the carb, or weaker spark through that plug wire for whatever reason, or maybe your compression is just slightly off on one rotor. The housings might not (they probably aren't) the same temperature making compression different between the two.
To answer the question a dozen and a half things can lead to this. Poor fuel delivery on that side of the carb, or weaker spark through that plug wire for whatever reason, or maybe your compression is just slightly off on one rotor. The housings might not (they probably aren't) the same temperature making compression different between the two.
03-04-20, 08:59 AM
#25
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Notice any misfires at idle? If not; don't think about it. If you do have a misfire; compression test it and stop worrying. Worrying will only shorten your enjoyment of the engine. Send it.
To answer the question a dozen and a half things can lead to this. Poor fuel delivery on that side of the carb, or weaker spark through that plug wire for whatever reason, or maybe your compression is just slightly off on one rotor. The housings might not (they probably aren't) the same temperature making compression different between the two.
To answer the question a dozen and a half things can lead to this. Poor fuel delivery on that side of the carb, or weaker spark through that plug wire for whatever reason, or maybe your compression is just slightly off on one rotor. The housings might not (they probably aren't) the same temperature making compression different between the two.