Little bit of weber help
09-30-13, 07:41 PM
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Little bit of weber help
Engine, street port 13b, weber 48 idf, racing beat duels out the back.
Situation, basically started from scratch with the jetting. Got f8 emulsion tubes, got a few sets of jets from 195 to 225, air correctors I have are 125 and 145 and I think a 165 set. Idle jets I have 65s in there, the chokes are 40. I had it running but it was really rich, and then I recently took out my 175 needle/seat for a 250 (no luck finding 300 at the time) and while I did that I was planning on changing out the bowl exhaust valve as well, but the one that was in it had no number or reference.i had it running, but rich with 225 mains and 145 air, but then I took out the needle and seat, swapped it, and I closed the exhaust valve with job weld. Now, I'm getting no fuel. Does the fuel that comes out that exhaust valve feed the accelerator pump? I get almost nothing out of squirters. Also can't see any fuel entering. Did close of all fuel to my acc. Pump?
Situation, basically started from scratch with the jetting. Got f8 emulsion tubes, got a few sets of jets from 195 to 225, air correctors I have are 125 and 145 and I think a 165 set. Idle jets I have 65s in there, the chokes are 40. I had it running but it was really rich, and then I recently took out my 175 needle/seat for a 250 (no luck finding 300 at the time) and while I did that I was planning on changing out the bowl exhaust valve as well, but the one that was in it had no number or reference.i had it running, but rich with 225 mains and 145 air, but then I took out the needle and seat, swapped it, and I closed the exhaust valve with job weld. Now, I'm getting no fuel. Does the fuel that comes out that exhaust valve feed the accelerator pump? I get almost nothing out of squirters. Also can't see any fuel entering. Did close of all fuel to my acc. Pump?
09-30-13, 08:14 PM
#2
Your problem is the F8 tube, put a F11 tube and re-tune, Also the needle/seat is used to allow fuel into the bowl, meaning a larger N&S will fill the bowl quicker, it has nothing to do with running rich. One more thing, get rid of the IDF unless you just want cruise around town.
09-30-13, 09:22 PM
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Yeah, not getting rid of the idf, it's perfectly capable of producing the performance and enough drive ability for what I'm looking for. Obviously a 250 needle and seat is going to fill the bowl faster, I meant with a close bowl exhaust valve. I don't have a rich problem, I have a not running because I'm getting no fuel. I'm pretty sure, f7, f8 or f11 should be manageable. That was a really half-assed effort, just upping your post count?
09-30-13, 09:41 PM
#4
Yeah, not getting rid of the idf, it's perfectly capable of producing the performance and enough drive ability for what I'm looking for. Obviously a 250 needle and seat is going to fill the bowl faster, I meant with a close bowl exhaust valve. I don't have a rich problem, I have a not running because I'm getting no fuel. I'm pretty sure, f7, f8 or f11 should be manageable. That was a really half-assed effort, just upping your post count?
10-01-13, 07:10 AM
#5
Rotary Freak
Yeah, not getting rid of the idf, it's perfectly capable of producing the performance and enough drive ability for what I'm looking for. Obviously a 250 needle and seat is going to fill the bowl faster, I meant with a close bowl exhaust valve. I don't have a rich problem, I have a not running because I'm getting no fuel. I'm pretty sure, f7, f8 or f11 should be manageable. That was a really half-assed effort, just upping your post count?
Eric
(and no, I am not trying to up my post count)
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10-01-13, 01:50 PM
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I haven't tried to adjust it. But, the exhaust valve at the bottom of the bowl is 100% shut! with jb weld. I will see if I can adjust it, see what happens. Thank you
10-02-13, 07:35 PM
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My 1968 Alfa Romeo had twin 40DCOEs.
My 1983 RX-7 had a single 45DCOE.
Have not worked on Webers since 1993, but!
A single even large Weber on a rotary does not have enough fuel surrounding the emulsion tubes to provide adequate acceleration fuel. You need the longest working acceleration pump setup.
You need the thinnest emulsion tubes so that the wells hold more fuel for acceleration.
Most likely need larger idle jets that can help mid range acceleration.
You may need to experiment with modifying the hole arrangement of the holes on the side of the emulsion tube to get the best transition from acceleration at midrange to when the wells go dry and the only fuel is through the fuel jets.
It took me a while to get my ported 12A to run perfectly on my 45DOCE with using the largest throats available for it.
Think of this comparison:
1290 cc Alfa engine with twin 40DCOE with 28 mm venturis on a stock engine and 32 on a short course car.
A 12A of 2.3 real ccs using a single 45DCOE with 40 mm venturis.
A single Weber on a rotary is really too small for the street but can be done.
I had about 5 sets of emulsion tubes, and a full range of fuel and air bleed jets.
Read up on Weber tuning. Start with proper idle tuning, then acceleration, and lastly with full power from midrange.
My 1983 RX-7 had a single 45DCOE.
Have not worked on Webers since 1993, but!
A single even large Weber on a rotary does not have enough fuel surrounding the emulsion tubes to provide adequate acceleration fuel. You need the longest working acceleration pump setup.
You need the thinnest emulsion tubes so that the wells hold more fuel for acceleration.
Most likely need larger idle jets that can help mid range acceleration.
You may need to experiment with modifying the hole arrangement of the holes on the side of the emulsion tube to get the best transition from acceleration at midrange to when the wells go dry and the only fuel is through the fuel jets.
It took me a while to get my ported 12A to run perfectly on my 45DOCE with using the largest throats available for it.
Think of this comparison:
1290 cc Alfa engine with twin 40DCOE with 28 mm venturis on a stock engine and 32 on a short course car.
A 12A of 2.3 real ccs using a single 45DCOE with 40 mm venturis.
A single Weber on a rotary is really too small for the street but can be done.
I had about 5 sets of emulsion tubes, and a full range of fuel and air bleed jets.
Read up on Weber tuning. Start with proper idle tuning, then acceleration, and lastly with full power from midrange.
10-05-13, 03:16 PM
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Confirmed that my jb welded bowl exhaust valve is causing a no fuel situation from my accel.pump squirters. What's the difference between a size zero exhaust valve and my jb weld special exhaust valve?
I do apologize for being short, and thank you for pointing me towards the f11 e tube, as. Have been looking around a bit more, it seems to be a better fit for my set, thank you.
I do apologize for being short, and thank you for pointing me towards the f11 e tube, as. Have been looking around a bit more, it seems to be a better fit for my set, thank you.
10-06-13, 03:54 PM
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"Pump By-pass Valve:
The pump by-pass valve is designed to allow fuel into the pump circuit and when depressed, by-pass a percentage (hole on the side of the valve) of the fuel delivered to the accelerator pump nozzle/jets. We have included the zero by-pass valve in our jet kit. This will deliver all of the available fuel to the engine and not by-pass fuel back to the fuel bowl. The accelerator pump by-pass valve is located in the bottom of the fuel bowl, one is required per carburetor."
This is from redline weber and seems to me that fuel is being bled into the fuel bowl from the pump circuit, which makes sense as to how it could function (as many members here are doing) with a closed valve there, but does not answer why I'm getting no fuel with my jb welded version of a "0" exhaust valve. Is it possible debris is clogging my pump from fuel and it's simply "back-filling" when I remove the plugged exhaust valve?
The pump by-pass valve is designed to allow fuel into the pump circuit and when depressed, by-pass a percentage (hole on the side of the valve) of the fuel delivered to the accelerator pump nozzle/jets. We have included the zero by-pass valve in our jet kit. This will deliver all of the available fuel to the engine and not by-pass fuel back to the fuel bowl. The accelerator pump by-pass valve is located in the bottom of the fuel bowl, one is required per carburetor."
This is from redline weber and seems to me that fuel is being bled into the fuel bowl from the pump circuit, which makes sense as to how it could function (as many members here are doing) with a closed valve there, but does not answer why I'm getting no fuel with my jb welded version of a "0" exhaust valve. Is it possible debris is clogging my pump from fuel and it's simply "back-filling" when I remove the plugged exhaust valve?
10-29-13, 01:23 PM
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*rotorholic, I wanted to apologize for the shortness and attitude about your comments. The f11 tube is nice, much less aggressive than the f8, starts better too.
As for the setup and the car, I got a zero exhaust valve, which does in fact allow fuel down into accel. Pump diaphragm and is closed the other way. Just wanted to post the results since I was never able to find the answer to this question. Car fires up great, revs great all the way to 8k rpm no problem.
As for the setup and the car, I got a zero exhaust valve, which does in fact allow fuel down into accel. Pump diaphragm and is closed the other way. Just wanted to post the results since I was never able to find the answer to this question. Car fires up great, revs great all the way to 8k rpm no problem.
10-30-13, 01:33 PM
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Your problem is the F8 tube, put a F11 tube and re-tune, Also the needle/seat is used to allow fuel into the bowl, meaning a larger N&S will fill the bowl quicker, it has nothing to do with running rich. One more thing, get rid of the IDF unless you just want cruise around town.
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