jet a weber dcoe
#1
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jet a weber dcoe
what jetting would be best for a weber 45mm to a 1983 12A stock engine. my future mods are going to be exhaust and headers.
i need 2 sizes for CHOKES, MAIN JETS, AIR CORRECTOR JETS, IDLE JETS, PUMP JETS.
i need 2 sizes for CHOKES, MAIN JETS, AIR CORRECTOR JETS, IDLE JETS, PUMP JETS.
#2
Rotary Enthusiast
depends on actual tuning.
Start with 34mm chokes. 190 air, 145 fuel, emulsion tubes I forgot but I think they were F3s. idle jets are extremely important but unfortunately I don't have my table here, but I once played with them and just screwed up my whole setup. Pump I forget also.
that should get you going. With that combo should be plenty. Whatever you do avoid going to big on the chokes. Also hit the timing to a couple of degrees advanced.
my humble .02 cents... I ran a DCOE for about 4 years great carb!
Start with 34mm chokes. 190 air, 145 fuel, emulsion tubes I forgot but I think they were F3s. idle jets are extremely important but unfortunately I don't have my table here, but I once played with them and just screwed up my whole setup. Pump I forget also.
that should get you going. With that combo should be plenty. Whatever you do avoid going to big on the chokes. Also hit the timing to a couple of degrees advanced.
my humble .02 cents... I ran a DCOE for about 4 years great carb!
#6
The Shadetree Project
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you're both wrong... f8's are most likely going to be too lean for washington driving.
Personally I'd try
idle: 60f9
aux choke: 3.5mm
main choke: 40mm
Accel jet: 45
main: 180
a/c: 150
e-tube: f-11
You should come to some of the Izzys meet's if you're in WA. there are quite a few weber nerds here. I'm turbo weber'd..
Personally I'd try
idle: 60f9
aux choke: 3.5mm
main choke: 40mm
Accel jet: 45
main: 180
a/c: 150
e-tube: f-11
You should come to some of the Izzys meet's if you're in WA. there are quite a few weber nerds here. I'm turbo weber'd..
Last edited by Hyper4mance2k; 01-11-07 at 01:36 AM.
#7
Stu-Tron Get Yo Groove On
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Originally Posted by Hyper4mance2k
you're both wrong... f8's are most likely going to be too lean for washington driving.
Personally I'd try
idle: 60f9
aux choke: 3.5mm
main choke: 40mm
Accel jet: 45
main: 180
a/c: 150
e-tube: f-11
You should come to some of the Izzys meet's if you're in WA. there are quite a few weber nerds here. I'm turbo weber'd..
Personally I'd try
idle: 60f9
aux choke: 3.5mm
main choke: 40mm
Accel jet: 45
main: 180
a/c: 150
e-tube: f-11
You should come to some of the Izzys meet's if you're in WA. there are quite a few weber nerds here. I'm turbo weber'd..
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#8
Yeah, shutup kid.
A/C is the air corrector jet, locaten on top of the emulsion tube under the screw cap. 220 is way too big for a stockport, the bigger the air bleed the less fuel at high rpm, a 160 is what I used on my stockport with a weber 48.
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40mm chokes sound too big for a street driven stock ported 12A motor - the carb will have very poor low rpm performance with those big chokes because there will not be enough air velocity thru them to decently and smoothly suck fuel up out of the float bowl and thru the main jet fuel delivery system at low rpm street driving conditions below 2000 rpm.
#11
RX for fun
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Originally Posted by coldy13
A/C is the air corrector jet, locaten on top of the emulsion tube under the screw cap. 220 is way too big for a stockport, the bigger the air bleed the less fuel at high rpm, a 160 is what I used on my stockport with a weber 48.
On the other hand, larger air jets will make it "rich" on low end but "lean" on top end.
But again, DCOE's and IDA's have different driving habits.
#12
The Shadetree Project
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Originally Posted by speedturn
40mm chokes sound too big for a street driven stock ported 12A motor - the carb will have very poor low rpm performance with those big chokes because there will not be enough air velocity thru them to decently and smoothly suck fuel up out of the float bowl and thru the main jet fuel delivery system at low rpm street driving conditions below 2000 rpm.
#15
Banned. I got OWNED!!!
Originally Posted by Hyper4mance2k
you're both wrong... f8's are most likely going to be too lean for washington driving.
Personally I'd try
idle: 60f9
aux choke: 3.5mm
main choke: 40mm
Accel jet: 45
main: 180
a/c: 150
e-tube: f-11
You should come to some of the Izzys meet's if you're in WA. there are quite a few weber nerds here. I'm turbo weber'd..
Personally I'd try
idle: 60f9
aux choke: 3.5mm
main choke: 40mm
Accel jet: 45
main: 180
a/c: 150
e-tube: f-11
You should come to some of the Izzys meet's if you're in WA. there are quite a few weber nerds here. I'm turbo weber'd..
#16
Banned. I got OWNED!!!
Originally Posted by coldy13
A/C is the air corrector jet, locaten on top of the emulsion tube under the screw cap. 220 is way too big for a stockport, the bigger the air bleed the less fuel at high rpm, a 160 is what I used on my stockport with a weber 48.
#17
Banned. I got OWNED!!!
Originally Posted by brandon davis
What are the driving characteristics between a DCOE and an IDA?
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Thanks for the response, but in my search for an intake manifold, i went to mazdatrix and bought a 48 ida manifold. does the same jetting apply?
can i put a 45dcoe on a 48 ida manifold? i doubt it, but i thought i would ask anyways.
Hyper4mance2k- at the moment my rx7 doesn't run below 1500rpm, so i would have to show up in my Impreza.
can i put a 45dcoe on a 48 ida manifold? i doubt it, but i thought i would ask anyways.
Hyper4mance2k- at the moment my rx7 doesn't run below 1500rpm, so i would have to show up in my Impreza.
#21
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Nice job guys There is very little info out here in the public domain on rotaries and IDA/DCOE jetting. The racers guard their secrets closely, and the only one I know who I consider and "expert" in weber jetting (that will actually openly share) is Robert of Rotary Shack fame. Most of the big names won't even mess with tweeking your carb or any induction issues unless they build an engine for you.
Note to moderator - you need to archive this thread and a few others that come to mind from the past few years that relate to Weber jetting.
Robert if u check back in here...what do you think of Speedturns comment. I agree those chockes seem a little big for a stock port 12a. I'm assuming the users running that must compensate with smaller mains.
Note to moderator - you need to archive this thread and a few others that come to mind from the past few years that relate to Weber jetting.
Robert if u check back in here...what do you think of Speedturns comment. I agree those chockes seem a little big for a stock port 12a. I'm assuming the users running that must compensate with smaller mains.
#22
Banned. I got OWNED!!!
Originally Posted by speedturn
40mm chokes sound too big for a street driven stock ported 12A motor - the carb will have very poor low rpm performance with those big chokes because there will not be enough air velocity thru them to decently and smoothly suck fuel up out of the float bowl and thru the main jet fuel delivery system at low rpm street driving conditions below 2000 rpm.
true, but i dont know many bone stock mazda drivers that putt thier rotarys around town a 2,000 rpm's let alone a rotorhead sporting a weber under the hood...
i have run as big as 42mm venturies on a stock port 12a (with dual exhaust and full MSD ignition) and seen power gains in the upper rpm's.. bottom end did suffer as expected but the results were what we were looking for.. on the other end of the spectrum,for someone that wants great low end, good midrange and dosnt mind the loss in top end power then 37mm venturies is what you want..
on a side note,anything bigger than 45-46mm venturies on a 48 mm carb you loose all bottom end and midrange due to the lack of velocity through the carb, but on a big j-bridge or a peaky p-port in a drag car thats ok, for a street car, thats a no-no = no driveability
#23
Banned. I got OWNED!!!
Originally Posted by cpa7man
Nice job guys There is very little info out here in the public domain on rotaries and IDA/DCOE jetting. The racers guard their secrets closely, and the only one I know who I consider and "expert" in weber jetting (that will actually openly share) is Robert of Rotary Shack fame. Most of the big names won't even mess with tweeking your carb or any induction issues unless they build an engine for you.
Note to moderator - you need to archive this thread and a few others that come to mind from the past few years that relate to Weber jetting.
Robert if u check back in here...what do you think of Speedturns comment. I agree those chockes seem a little big for a stock port 12a. I'm assuming the users running that must compensate with smaller mains.
Note to moderator - you need to archive this thread and a few others that come to mind from the past few years that relate to Weber jetting.
Robert if u check back in here...what do you think of Speedturns comment. I agree those chockes seem a little big for a stock port 12a. I'm assuming the users running that must compensate with smaller mains.
oh and a general rule of thumb is the bigger the venturi you run, the smaller the air jet you use, to compensate for the loss of low pressure area through the carb(thats what pulls the fuel up the jet, through the emulsion tube, aux venturi and eventually down the carb throat)
#24
OBEY YOUR MAZDA
Originally Posted by nismoracer99
can i put a 45dcoe on a 48 ida manifold?
You might get some fuel issues though (sidedraft/downdraft)