Racingbeat Holley or rotaryshack Weber or unknown 48 Ida
05-31-16, 12:07 AM
#27
Full Member
Thread Starter
Racingbeat Holley or rotaryshack Weber or unknown 48 Ida
As for the jets on ebay you send me I will try to get them in the Netherlands as the shipping cost are just to much
This one seems right to me
http://www.rockauto.com/en/moreinfo....nid=318&jpid=1
I've found an normal drillset
http://www.hobby-en-modelbouw.nl/con...dschappen.html
This one seems right to me
http://www.rockauto.com/en/moreinfo....nid=318&jpid=1
I've found an normal drillset
http://www.hobby-en-modelbouw.nl/con...dschappen.html
Last edited by klabatzie; 05-31-16 at 12:23 AM.
05-31-16, 12:39 PM
#29
Full Member
Thread Starter
Oké I thought that from this set the air horn gasket was better. I didn't see that the crush washers were different
Did some filing today and one booster venturi is done (I think😆)
Did some filing today and one booster venturi is done (I think😆)
05-31-16, 02:45 PM
#30
Full Member
Thread Starter
All of the boosters are done.
Drillset ordered
Found a gasket set in the garage has aluminum crush rings but not the acceleration pump diagram and the ( from my view the wrong airhorngasket, the one with the two holes between the 1st and 2nd stage) forgot I ordered it a long time ago
So I'll just order the other one.
Should I be smoothing out the air horn ridge or doesn't it matter?
And one question about the main venturi diameter: You wrote that the diameter should be between 23 and 24 mm do you think it's better to stay at 23 for more air velocity? I would recon that it will mix the air fuel better?
Drillset ordered
Found a gasket set in the garage has aluminum crush rings but not the acceleration pump diagram and the ( from my view the wrong airhorngasket, the one with the two holes between the 1st and 2nd stage) forgot I ordered it a long time ago
So I'll just order the other one.
Should I be smoothing out the air horn ridge or doesn't it matter?
And one question about the main venturi diameter: You wrote that the diameter should be between 23 and 24 mm do you think it's better to stay at 23 for more air velocity? I would recon that it will mix the air fuel better?
05-31-16, 03:27 PM
#31
Perfect job on the boosters. Now be sure to wax a "finishing nail punch" tool to lightly expand the bottom of the booster (wax prevents the tool from getting stuck inside the booster).
No need to smooth anything on the air horn. I stopped doing it a long time ago. But if you really want to, I suppose you could. I just won't do it these days.
23mm does allow for more vacuum, but has less low end torque and power than 24mm. However 24mm invites drivability problems because the transition circuit was only designed officially for stock 20mm. I've found on my 74 ported 13B with a big REPU intake manifold, the biggest size I could get away with and still have drivability that is "good enough" on the bigger engine, is 25.35mm. I've done four carbs in this size ranging from 25.25mm, 25.30mm, 25.35mm and 25.45mm. The 25.25mm drives well but the 25.35mm has more power. The 25.45mm has a more noticeable flat spot at around 1700RPM that all hogged Nikkis suffer (due to the transition circuit not being big enough, but can't be changed). A good, well adjusted accel pump covers for this so you rarely notice it while driving. But just sitting there idling it up, you can manually sometimes find the 1700 dead zone. Wankel=awesome has found this as well on his 24.5mm carb, which doesn't bother him while driving due to his accel pump covering for it.
Thus to answer your question, you could try for 24.0mm if you want to, and it will make more power than 23.0mm, and is what I would recommend as you appear to be able to work on these carbs well, but the 23.0mm might drive a little bit better for you on your 12A. I don't know the details of your engine or your setup IE ignition, exhaust, porting, intake manifold etc.
There is a local guy for whom I did a set of 24.15mm venturis, which is running strongly on his stockport 12A, under my supervision. It is working great for him!
Just do a tune exactly like I recommend, and it will allow you to use 24mm.
pri short slow (idle air bleeds): 118 to 124
pri long slow (transition circuit which must remain stock): 46
pri air main: 70
pri fuel: 116 to 118 (maybe 120 but I doubt it)
sec fuel: 145
sec air main: 80
sec long slow: solder filled
sec short slow: stock nickel plated 60
The only part on your carb that will require any fine tuning will be your primary fuel jets. Start with a set of 116 and 118 from jetsRus.com and see how they affect your AFR. All the rest is already figured out.
No need to smooth anything on the air horn. I stopped doing it a long time ago. But if you really want to, I suppose you could. I just won't do it these days.
23mm does allow for more vacuum, but has less low end torque and power than 24mm. However 24mm invites drivability problems because the transition circuit was only designed officially for stock 20mm. I've found on my 74 ported 13B with a big REPU intake manifold, the biggest size I could get away with and still have drivability that is "good enough" on the bigger engine, is 25.35mm. I've done four carbs in this size ranging from 25.25mm, 25.30mm, 25.35mm and 25.45mm. The 25.25mm drives well but the 25.35mm has more power. The 25.45mm has a more noticeable flat spot at around 1700RPM that all hogged Nikkis suffer (due to the transition circuit not being big enough, but can't be changed). A good, well adjusted accel pump covers for this so you rarely notice it while driving. But just sitting there idling it up, you can manually sometimes find the 1700 dead zone. Wankel=awesome has found this as well on his 24.5mm carb, which doesn't bother him while driving due to his accel pump covering for it.
Thus to answer your question, you could try for 24.0mm if you want to, and it will make more power than 23.0mm, and is what I would recommend as you appear to be able to work on these carbs well, but the 23.0mm might drive a little bit better for you on your 12A. I don't know the details of your engine or your setup IE ignition, exhaust, porting, intake manifold etc.
There is a local guy for whom I did a set of 24.15mm venturis, which is running strongly on his stockport 12A, under my supervision. It is working great for him!
Just do a tune exactly like I recommend, and it will allow you to use 24mm.
pri short slow (idle air bleeds): 118 to 124
pri long slow (transition circuit which must remain stock): 46
pri air main: 70
pri fuel: 116 to 118 (maybe 120 but I doubt it)
sec fuel: 145
sec air main: 80
sec long slow: solder filled
sec short slow: stock nickel plated 60
The only part on your carb that will require any fine tuning will be your primary fuel jets. Start with a set of 116 and 118 from jetsRus.com and see how they affect your AFR. All the rest is already figured out.
05-31-16, 03:58 PM
#32
Full Member
Thread Starter
Racingbeat Holley or rotaryshack Weber or unknown 48 Ida
Thanks for the compliment! I'm pretty pleased with how they've turned out.
I have a racingbeat long primary exhaust on an completely stock engine.
I would like to get more torque of course
so I'll guess I'll go for the 24. I'm going to make a call to an carburation specialist if he can help me get the jets. I wil order the ones you recommended and maybe a few different sized main fuel jets
Do you also make changes on the intake manifold? I think it's maybe better to close the passages for airpump and emissions so there would be a smoother flow
I have a racingbeat long primary exhaust on an completely stock engine.
I would like to get more torque of course
so I'll guess I'll go for the 24. I'm going to make a call to an carburation specialist if he can help me get the jets. I wil order the ones you recommended and maybe a few different sized main fuel jetsDo you also make changes on the intake manifold? I think it's maybe better to close the passages for airpump and emissions so there would be a smoother flow
Last edited by klabatzie; 05-31-16 at 04:01 PM.
05-31-16, 05:44 PM
#33
Perfect exhaust system! Perfect for 24mm!
The manifold passages can be blocked, yes. Determine which nipple(s) to keep in the carb spacer for a PCV system to pull moisture from the oil fill tube. I think you keep the middle nipple on an FB spacer because it communicates with both primary runners. I have yet to try it though. I had to block all of mine off for boost, to prevent boost leaks and I drilled a hole in my oil fill cap. Works well enough (only gets moisture in the winter now, under the cap, which eventually evaporates).
The manifold passages can be blocked, yes. Determine which nipple(s) to keep in the carb spacer for a PCV system to pull moisture from the oil fill tube. I think you keep the middle nipple on an FB spacer because it communicates with both primary runners. I have yet to try it though. I had to block all of mine off for boost, to prevent boost leaks and I drilled a hole in my oil fill cap.
Works well enough (only gets moisture in the winter now, under the cap, which eventually evaporates).
05-31-16, 07:36 PM
#34
carb whisperer
I read this with excitement everyday because we managed to persuade someone into building their Nikki instead of going aftermarket.
I tried all the aftermarket first, then came back to Nikki. Would have saved a load of cash had I done that to start with.
I tried all the aftermarket first, then came back to Nikki. Would have saved a load of cash had I done that to start with.
06-01-16, 08:54 AM
#35
Waffles - hmmm good
iTrader: (1)
Its nice to see someone take our advice on the Nikki. Its a great carb to use for a rotary.
Dont forget to get rid of the butterfly in the manifold and add the channel into it as well. I also bored out the rear secondary a bit to match the front one as much as possible. Just used a cutoff wheel and a dremel to get it all out. Easy to do too.
Before:
After:
Dont forget to get rid of the butterfly in the manifold and add the channel into it as well. I also bored out the rear secondary a bit to match the front one as much as possible. Just used a cutoff wheel and a dremel to get it all out. Easy to do too.
Before:
After:
Last edited by t_g_farrell; 06-01-16 at 08:56 AM.
06-01-16, 12:27 PM
#36
Full Member
Thread Starter
Its nice to see someone take our advice on the Nikki. Its a great carb to use for a rotary.
Dont forget to get rid of the butterfly in the manifold and add the channel into it as well. I also bored out the rear secondary a bit to match the front one as much as possible. Just used a cutoff wheel and a dremel to get it all out. Easy to do too.
Before:
After:
Dont forget to get rid of the butterfly in the manifold and add the channel into it as well. I also bored out the rear secondary a bit to match the front one as much as possible. Just used a cutoff wheel and a dremel to get it all out. Easy to do too.
Before:
After:
06-01-16, 02:11 PM
#38
Full Member
Thread Starter
I'm finding out what I have to work with jet wise.
Primary main jet is 93
Main airbleed 90
Slow long airbleed 40
2nd slow air 150
Secondary main fuel is 160
Main airbleed 140
Slow long airbleed ?
2nd nickel plated 60
Also got an richer airbleed that is 40
I've contacted 2 carburation specialist today and they can not help me with the jets you recommended. I wil try to contact a parts manager that has frequent parts from the USA and see if he can help me to get the parts at one reseller and keeping the shipping cost down
Primary main jet is 93
Main airbleed 90
Slow long airbleed 40
2nd slow air 150
Secondary main fuel is 160
Main airbleed 140
Slow long airbleed ?
2nd nickel plated 60
Also got an richer airbleed that is 40
I've contacted 2 carburation specialist today and they can not help me with the jets you recommended. I wil try to contact a parts manager that has frequent parts from the USA and see if he can help me to get the parts at one reseller and keeping the shipping cost down
06-01-16, 02:28 PM
#39
The primary long slow is actually 46. The stamping is tiny and not centered.
Using your list, let me add my tune in bold
Primary main jet is 93 116 to 118
Main airbleed 90 70
Slow long airbleed 40 stock 46
2nd slow air 150 118 to 125
Secondary main fuel is 160 145
Main airbleed 140 80
Slow long airbleed ? solder filled
2nd nickel plated 60 stock
Richer air bleed? Please explain. Is it down inside the float bowl? If so, it is a jet, I think. I leave it alone. It becomes irrelevant when you mod a carb for performance.
The jets that fit a Nikki are a specific size, length and thread pitch. I don't recall what it is but I can look. Ok, it is 5mm x .8mm thread pitch and length is whatever it is. The jets from JetsRus work.
As for those pics, um you should have pulled the OMP nipples out. I always do. Makes life easier to drive the venturis out. I use an old chuck from a drill (three fingers to grip the brass) but you might have a better solution.
Using your list, let me add my tune in bold
Primary main jet is 93 116 to 118
Main airbleed 90 70
Slow long airbleed 40 stock 46
2nd slow air 150 118 to 125
Secondary main fuel is 160 145
Main airbleed 140 80
Slow long airbleed ? solder filled
2nd nickel plated 60 stock
Richer air bleed? Please explain. Is it down inside the float bowl? If so, it is a jet, I think. I leave it alone. It becomes irrelevant when you mod a carb for performance.
The jets that fit a Nikki are a specific size, length and thread pitch. I don't recall what it is but I can look. Ok, it is 5mm x .8mm thread pitch and length is whatever it is. The jets from JetsRus work.
As for those pics, um you should have pulled the OMP nipples out. I always do. Makes life easier to drive the venturis out. I use an old chuck from a drill (three fingers to grip the brass) but you might have a better solution.
06-01-16, 02:31 PM
#40
By the way, any plans on hogging your secondaries? If so, I can tell you that at stock 28mm, the jetting will be 140 to 145. If you go larger, I've gone up to 32.7mm and I DO NOT recommend anyone go this big, ever. You cut into the little cavity on the outside of the venturi which must be filled in with putty. DO NOT do this!!! I mention it for academics only. The jets I used are the factory 160s that gave me an AFR of around 11.3 in boost.
06-01-16, 02:42 PM
#41
Full Member
Thread Starter
By the way, any plans on hogging your secondaries? If so, I can tell you that at stock 28mm, the jetting will be 140 to 145. If you go larger, I've gone up to 32.7mm and I DO NOT recommend anyone go this big, ever. You cut into the little cavity on the outside of the venturi which must be filled in with putty. DO NOT do this!!! I mention it for academics only. The jets I used are the factory 160s that gave me an AFR of around 11.3 in boost.
The primary long slow is actually 46. The stamping is tiny and not centered.
Using your list, let me add my tune in bold
Primary main jet is 93 116 to 118
Main airbleed 90 70
Slow long airbleed 40 stock 46
2nd slow air 150 118 to 125
Secondary main fuel is 160 145
Main airbleed 140 80
Slow long airbleed ? solder filled
2nd nickel plated 60 stock
Richer air bleed? Please explain. Is it down inside the float bowl? If so, it is a jet, I think. I leave it alone. It becomes irrelevant when you mod a carb for performance.
The jets that fit a Nikki are a specific size, length and thread pitch. I don't recall what it is but I can look. Ok, it is 5mm x .8mm thread pitch and length is whatever it is. The jets from JetsRus work.
As for those pics, um you should have pulled the OMP nipples out. I always do. Makes life easier to drive the venturis out. I use an old chuck from a drill (three fingers to grip the brass) but you might have a better solution.
Using your list, let me add my tune in bold
Primary main jet is 93 116 to 118
Main airbleed 90 70
Slow long airbleed 40 stock 46
2nd slow air 150 118 to 125
Secondary main fuel is 160 145
Main airbleed 140 80
Slow long airbleed ? solder filled
2nd nickel plated 60 stock
Richer air bleed? Please explain. Is it down inside the float bowl? If so, it is a jet, I think. I leave it alone. It becomes irrelevant when you mod a carb for performance.
The jets that fit a Nikki are a specific size, length and thread pitch. I don't recall what it is but I can look. Ok, it is 5mm x .8mm thread pitch and length is whatever it is. The jets from JetsRus work.
As for those pics, um you should have pulled the OMP nipples out. I always do. Makes life easier to drive the venturis out. I use an old chuck from a drill (three fingers to grip the brass) but you might have a better solution.
The richer air bleeds sits above the secondary ports in the picture there ate two holes. One is an airbleed the other is plugged
06-01-16, 02:45 PM
#42
Full Member
Thread Starter
By the way, any plans on hogging your secondaries? If so, I can tell you that at stock 28mm, the jetting will be 140 to 145. If you go larger, I've gone up to 32.7mm and I DO NOT recommend anyone go this big, ever. You cut into the little cavity on the outside of the venturi which must be filled in with putty. DO NOT do this!!! I mention it for academics only. The jets I used are the factory 160s that gave me an AFR of around 11.3 in boost.
06-01-16, 09:46 PM
#44
Originally Posted by klabatzie
I taped the venturi out with a socket that I modified to clear the omp nozzle
The richer air bleeds sits above the secondary ports in the picture there ate two holes. One is an airbleed the other is plugged
06-01-16, 09:50 PM
#45
Agreed. 24mm and 28mm are a good size.
Fill them all the way. You want to see solder inside the two sets of holes near the bottom, and fill it up to the top. Don't worry about filling the holes at the very bottom as I have not tried that. I couldn't tell you want it would do, and seems difficult with a potentially higher failure rate. You don't want solder falling out and plugging something.
Fill them all the way. You want to see solder inside the two sets of holes near the bottom, and fill it up to the top. Don't worry about filling the holes at the very bottom as I have not tried that. I couldn't tell you want it would do, and seems difficult with a potentially higher failure rate. You don't want solder falling out and plugging something.
06-02-16, 06:44 AM
#47
carb whisperer
Dont you just drip it down the bleed? I didnt know when he said "solder filled" he meant filling the emulsions bleeds from the side of the tube.
I thought he achieved that by filling the whole tube with solder, I did a similar thing with JB weld. I only filled the very top though.
I thought he achieved that by filling the whole tube with solder, I did a similar thing with JB weld. I only filled the very top though.
06-02-16, 08:11 AM
#48
Full Member
Thread Starter
Dont you just drip it down the bleed? I didnt know when he said "solder filled" he meant filling the emulsions bleeds from the side of the tube.
I thought he achieved that by filling the whole tube with solder, I did a similar thing with JB weld. I only filled the very top though.
I thought he achieved that by filling the whole tube with solder, I did a similar thing with JB weld. I only filled the very top though.
06-02-16, 12:41 PM
#49
I heat the complete tube and let solder fill it. The solder fills the tube and cools it, thus freezing the solder in the process. It took a little bit of finesse but I figured out a good technique that works.
Oh and I hold the tube in the middle with a needlenose vicegrip. The vice grip is held in a bench vice. the excess solder just drips on the smooth garage floor and is easily cleaned up later.
It looks like your way is keeping the bottom of the tube cold and could deform its shape. No wonder you are having problems.
Oh and I hold the tube in the middle with a needlenose vicegrip. The vice grip is held in a bench vice. the excess solder just drips on the smooth garage floor and is easily cleaned up later.
It looks like your way is keeping the bottom of the tube cold and could deform its shape. No wonder you are having problems.