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74superTN
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Joined: April 01, 2007
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Location: Port Saint Lucie, FL
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 Posted: Fri Oct 12, 2018 9:29 am Post subject: Dual Weber 40's leak at Wide Open Throttle |
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So my newly installed Weber 40's leak at wide open throttle. I'm running a 3.5psi fuel pump from CB Performance and that's also where the carbs came from. I checked the floats and their at 14mm which was what their paperwork recommends. Any ideas? It's a type IV motor
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73 Thing
80 Vanagon Westy |
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busman78
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Joined: August 17, 2004
Posts: 4524
Location: Oklahoma City, OK
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| Posted: Fri Oct 12, 2018 10:36 am Post subject: Re: Dual Weber 40's leak at Wide Open Throttle |
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| Leak from where? |
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Wildthings
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Joined: March 13, 2005
Posts: 50351
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| Posted: Fri Oct 12, 2018 10:36 am Post subject: Re: Dual Weber 40's leak at Wide Open Throttle |
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| How can you tell a carb is leaking at wide open throttle if the engine isn't on a test stand hooked to a dyno? |
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74superTN
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Joined: April 01, 2007
Posts: 675
Location: Port Saint Lucie, FL
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| Posted: Fri Oct 12, 2018 10:49 am Post subject: Re: Dual Weber 40's leak at Wide Open Throttle |
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Leaking from the throttle shaft
Let me rephrase, I operate the throttle of the carbs while running with the engine lid off. I can slowly see fuel start to build up on the throttle shafts but only when the throttles are fully open.
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SGKent 
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Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Fri Oct 12, 2018 10:51 am Post subject: Re: Dual Weber 40's leak at Wide Open Throttle |
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yes - leak where and is this motor running, or is it static? Is a fuel pump running?
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74superTN
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Joined: April 01, 2007
Posts: 675
Location: Port Saint Lucie, FL
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| Posted: Fri Oct 12, 2018 11:05 am Post subject: Re: Dual Weber 40's leak at Wide Open Throttle |
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Fuel pump running, 3.5 rotary from CB Performance
Engine is running and installed in the vehicle
I have the deck lid off from up top and i'm moving the throttles by hand
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SGKent
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Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Fri Oct 12, 2018 11:13 am Post subject: Re: Dual Weber 40's leak at Wide Open Throttle |
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| 74superTN wrote: |
Fuel pump running, 3.5 rotary from CB Performance
Engine is running and installed in the vehicle
I have the deck lid off from up top and i'm moving the throttles by hand |
still didn't tell us where it is leaking
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74superTN
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Joined: April 01, 2007
Posts: 675
Location: Port Saint Lucie, FL
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| Posted: Fri Oct 12, 2018 11:18 am Post subject: Re: Dual Weber 40's leak at Wide Open Throttle |
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from the throttle shaft, bottom center of the carb
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Wildthings
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Joined: March 13, 2005
Posts: 50351
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| Posted: Fri Oct 12, 2018 11:32 am Post subject: Re: Dual Weber 40's leak at Wide Open Throttle |
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I am guessing this only happens on a cold engine? When hot the fuel will evaporate off the throttle plates and not have a chance to run through the throttle shaft bushing. It is pretty normal to see this on a cold non running engine.
Last edited by Wildthings on Fri Oct 12, 2018 1:18 pm; edited 1 time in total |
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busman78
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Joined: August 17, 2004
Posts: 4524
Location: Oklahoma City, OK
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| Posted: Fri Oct 12, 2018 1:07 pm Post subject: Re: Dual Weber 40's leak at Wide Open Throttle |
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Bottom center and the shaft is getting wet my guess would be you are leaking from the accelerator pump cover and it is running onto the shaft.
Use a small mirror and flashlight to see where the fuel is leaking from.
Also should be able to remove the carb and with the bowl fuel cause it to leak by operating the throttle. |
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74superTN
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Joined: April 01, 2007
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Location: Port Saint Lucie, FL
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| Posted: Fri Oct 12, 2018 3:45 pm Post subject: Re: Dual Weber 40's leak at Wide Open Throttle |
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I don't know what the issue was but my mechanic told me I had my fuel pump located too close to the carbs so I moved it back by my fuel tank (Vanagon) and just drove about 30 minutes with no leaks..idk
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74superTN
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Location: Port Saint Lucie, FL
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| Posted: Sun Oct 14, 2018 4:33 am Post subject: Re: Dual Weber 40's leak at Wide Open Throttle |
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After further inspection, it looks like it only leaks a few minutes after I shut my engine down after a long drive.
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udidwht
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Joined: March 06, 2005
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Location: Seattle, WA./ HB, Ca./ Shizuoka, Japan
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| Posted: Sun Oct 14, 2018 12:21 pm Post subject: Re: Dual Weber 40's leak at Wide Open Throttle |
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What height were the floats set at?
We're you certain not to have depressed the ball when adjusting them?
Was the carb top gasket in place when this was done?
Fuel pressure?
You certain the air bleed ports aren't blocked? (carb top)
With the engine NOT running and your pumping the gas you will see fuel come from the carbs. The fuel must go somewhere and the most likely spot is the top of the butterfly then across the shaft.
Unless you plan on starting the engine stop pumping the pedal.
All carbs when bought new or used must be tore down and checked thoroughly. Always.
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1972 Westy Hardtop/Type-4 2056cc
96mm Biral AA P/C's~7.8:1CR
Headflow Masters New AMC 42x36mm heads w/Porsche swivel adjusters
71mm Stroke
73 Web Cam w/Web solids
Dual 40mm IDF Webers - LM-2 - 47.5 idles/125 mains/190 air corr./F11 tubes/28mm Vents - Float height 10.45mm/Drop 32mm
Bosch SVDA w/Pertronix module (7.5 initial 28 total @ 3400rpm)
Bosch W8CC plugs
Pertronix Flamethrower 40K coil
S&S 4-1 w/Walker QP 17862
3 rib 002 Trans
185R14 Hankook tires |
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74superTN
Samba Member
Joined: April 01, 2007
Posts: 675
Location: Port Saint Lucie, FL
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| Posted: Sun Oct 14, 2018 4:04 pm Post subject: Re: Dual Weber 40's leak at Wide Open Throttle |
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| udidwht wrote: |
What height were the floats set at?
We're you certain not to have depressed the ball when adjusting them?
Was the carb top gasket in place when this was done?
Fuel pressure?
You certain the air bleed ports aren't blocked? (carb top)
With the engine NOT running and your pumping the gas you will see fuel come from the carbs. The fuel must go somewhere and the most likely spot is the top of the butterfly then across the shaft.
Unless you plan on starting the engine stop pumping the pedal.
All carbs when bought new or used must be tore down and checked thoroughly. Always. |
So i'm dumb, explain where the air bleed ports are?
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udidwht
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Joined: March 06, 2005
Posts: 3779
Location: Seattle, WA./ HB, Ca./ Shizuoka, Japan
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| Posted: Sun Oct 14, 2018 4:40 pm Post subject: Re: Dual Weber 40's leak at Wide Open Throttle |
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| 74superTN wrote: |
| udidwht wrote: |
What height were the floats set at?
We're you certain not to have depressed the ball when adjusting them?
Was the carb top gasket in place when this was done?
Fuel pressure?
You certain the air bleed ports aren't blocked? (carb top)
With the engine NOT running and your pumping the gas you will see fuel come from the carbs. The fuel must go somewhere and the most likely spot is the top of the butterfly then across the shaft.
Unless you plan on starting the engine stop pumping the pedal.
All carbs when bought new or used must be tore down and checked thoroughly. Always. |
So i'm dumb, explain where the air bleed ports are? |
The air bleed ports are the tiny openings in the carb top (main body) that allow air to be brought into the idle jet circuit to mix with the fuel.
In the 12th pic down in the 'Setting up your IDF's'. You can just see them on the left & right side of the fuel bowl above where the main stacks are screwed into.
You want to be certain that the gasket does not block/cover those ports.
And be very CAREFUL if you try to remove the brass pin that holds he float on. Do not remove it unless you need to replace the needle/seat. You do not want to break the aluminum boss on either side that holds the pin in place 
https://www.rezrov.net/www.carburetorclinic.com/index.htm
_________________
1972 Westy Hardtop/Type-4 2056cc
96mm Biral AA P/C's~7.8:1CR
Headflow Masters New AMC 42x36mm heads w/Porsche swivel adjusters
71mm Stroke
73 Web Cam w/Web solids
Dual 40mm IDF Webers - LM-2 - 47.5 idles/125 mains/190 air corr./F11 tubes/28mm Vents - Float height 10.45mm/Drop 32mm
Bosch SVDA w/Pertronix module (7.5 initial 28 total @ 3400rpm)
Bosch W8CC plugs
Pertronix Flamethrower 40K coil
S&S 4-1 w/Walker QP 17862
3 rib 002 Trans
185R14 Hankook tires |
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74superTN
Samba Member
Joined: April 01, 2007
Posts: 675
Location: Port Saint Lucie, FL
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| Posted: Mon Oct 15, 2018 4:51 am Post subject: Re: Dual Weber 40's leak at Wide Open Throttle |
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ok thanks, I'll check those out!
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74superTN
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Joined: April 01, 2007
Posts: 675
Location: Port Saint Lucie, FL
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| Posted: Wed Jan 02, 2019 1:30 pm Post subject: Re: Dual Weber 40's leak at Wide Open Throttle |
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Update, issue fixed. I installed the Phenolic Insulators from Gansmann industries. Worked like a champ!
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udidwht
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Location: Seattle, WA./ HB, Ca./ Shizuoka, Japan
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| Posted: Wed Jan 02, 2019 3:06 pm Post subject: Re: Dual Weber 40's leak at Wide Open Throttle |
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Between the carb and manifold?
_________________
1972 Westy Hardtop/Type-4 2056cc
96mm Biral AA P/C's~7.8:1CR
Headflow Masters New AMC 42x36mm heads w/Porsche swivel adjusters
71mm Stroke
73 Web Cam w/Web solids
Dual 40mm IDF Webers - LM-2 - 47.5 idles/125 mains/190 air corr./F11 tubes/28mm Vents - Float height 10.45mm/Drop 32mm
Bosch SVDA w/Pertronix module (7.5 initial 28 total @ 3400rpm)
Bosch W8CC plugs
Pertronix Flamethrower 40K coil
S&S 4-1 w/Walker QP 17862
3 rib 002 Trans
185R14 Hankook tires |
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74superTN
Samba Member
Joined: April 01, 2007
Posts: 675
Location: Port Saint Lucie, FL
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| Posted: Thu Jan 03, 2019 4:34 am Post subject: Re: Dual Weber 40's leak at Wide Open Throttle |
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| udidwht wrote: |
| Between the carb and manifold? |
Yep, between the top of manifold and the carb
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udidwht
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Joined: March 06, 2005
Posts: 3779
Location: Seattle, WA./ HB, Ca./ Shizuoka, Japan
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| Posted: Thu Jan 03, 2019 9:40 am Post subject: Re: Dual Weber 40's leak at Wide Open Throttle |
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| 74superTN wrote: |
| udidwht wrote: |
| Between the carb and manifold? |
Yep, between the top of manifold and the carb |
Correct.
It's hit and miss if ones set up ends up needing a set on the manifolds. As for the fuel weep after shutdown (heat-soak related). This is more common than most realize. In fact, many don't don't but it's also not something to lose sleep over. With open air carb/s you will get fuel on the outside of them.
Be sure the lead plugs at the base of the carb are either tapped and threaded/plugged. Or JB Weld them. They will come loose overtime due to vibration.
_________________
1972 Westy Hardtop/Type-4 2056cc
96mm Biral AA P/C's~7.8:1CR
Headflow Masters New AMC 42x36mm heads w/Porsche swivel adjusters
71mm Stroke
73 Web Cam w/Web solids
Dual 40mm IDF Webers - LM-2 - 47.5 idles/125 mains/190 air corr./F11 tubes/28mm Vents - Float height 10.45mm/Drop 32mm
Bosch SVDA w/Pertronix module (7.5 initial 28 total @ 3400rpm)
Bosch W8CC plugs
Pertronix Flamethrower 40K coil
S&S 4-1 w/Walker QP 17862
3 rib 002 Trans
185R14 Hankook tires |
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