Leaky Holley
Thread Starter
Burning Brakes
Joined: May 2003
Posts: 794
Likes: 178
From: Hilton New York
Leaky Holley
You guys have done great on my last two questions. I bet you can get three in a row 
My Holley 4160 on my '66 327/350 is leaking. Looks like just when I turn the car off ( I know I should just keep driving
) It seems to seep from under the front left side of the carb. It could be leaking from the accellerator pump.
Anybody had a similar problem ?
DFA
My Holley 4160 on my '66 327/350 is leaking. Looks like just when I turn the car off ( I know I should just keep driving
) It seems to seep from under the front left side of the carb. It could be leaking from the accellerator pump.Anybody had a similar problem ?
DFA
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Joined: Mar 2001
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From: Mustang OK
2026 Corvette of the Year Finalist - Modified
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It is VERY possible that it is the acc pump. If so, then most likely the pump diaphragm has a split in it. The only fix is to remove the carb, remove the 4 screws and install a new diaphragm. Toooooooooooo easy!
Racer
Joined: Jun 2003
Posts: 290
Likes: 1
From: Torrington Ct
It might be leaking out of the throttle shaft but if it is leaking out there the source of the leak is likely not at the throttle shaft. When the car is sitting still there is no gas anywhere near the throttle shaft / linkage unless the gas is over flowing from the bowls. When you see gas coming out from the area around the shaft you need to think about things like the float, needle & seat and possibly the gaskets in between the metering plate and the carb body. Also the shaft hole in the carb base may be worn oversize with the years of use. This makes it easier for the gas to run past the shat but the source of the leak is still elsewhere than the throttle linkage.
Also todays gas has a tendency to turn to vapor at lower temps than the gas of days gone by. The result is that the gas can perculate (vaporize) at a lower ambient temp and then it flows out of the carb bowl running down into the carb venturies when the car sits after running. The gas will hit the closed throttle plates and then run out the side of the throttle shaft producing what appears to be a leak at the throttle linkage. This vapor point problem can be a real PIA but some careful tuning of settings in the carb (assuming the carb is in tip top shape) can fix the overflow.
Also todays gas has a tendency to turn to vapor at lower temps than the gas of days gone by. The result is that the gas can perculate (vaporize) at a lower ambient temp and then it flows out of the carb bowl running down into the carb venturies when the car sits after running. The gas will hit the closed throttle plates and then run out the side of the throttle shaft producing what appears to be a leak at the throttle linkage. This vapor point problem can be a real PIA but some careful tuning of settings in the carb (assuming the carb is in tip top shape) can fix the overflow.
Last edited by hpexpatriot; May 25, 2007 at 10:23 PM.
Racer
Joined: Jun 2003
Posts: 290
Likes: 1
From: Torrington Ct
It might be leaking out of the throttle shaft but if it is the source of the leak is not at the throttle shaft. When the car is sitting still there is no gas anywhere near the throttle shaft / linkage unless the gas is over flowing the bowls. When you see gas coming out from the area around the shaft you need to think about things like the float, needle & seat and possibly the gasjets in between the metering plate and the carb body.
Also todays gas has a tendency to turn to vapor at lower temps than the gas of days gone by. The result is that he gas can perculate (vaporize) at a lower ambient temp and then it flows out of the carb by running into the carb venturies. the gas will hit the closed throttle plates and then runs out the side of the throttle shaft and producing what appears to be a leak at the throttle linkage. Check the accel pump first that is a prime candidate but other things can be at fault.
Also todays gas has a tendency to turn to vapor at lower temps than the gas of days gone by. The result is that he gas can perculate (vaporize) at a lower ambient temp and then it flows out of the carb by running into the carb venturies. the gas will hit the closed throttle plates and then runs out the side of the throttle shaft and producing what appears to be a leak at the throttle linkage. Check the accel pump first that is a prime candidate but other things can be at fault.
Racer
Joined: Aug 2003
Posts: 404
Likes: 0
From: Sitka Alaska
I would think a split accelerator pump diaphram would cause hesitation problems when trying to take off from a stop? Why not just try snugging up all the bowl screws first, then the pump screws, and check the fuel line and fittings at the carb.
Jerry
Jerry
Le Mans Master
Joined: Feb 2006
Posts: 6,048
Likes: 5
From: "cutesy" TN
It might be leaking out of the throttle shaft but if it is leaking out there the source of the leak is likely not at the throttle shaft. When the car is sitting still there is no gas anywhere near the throttle shaft / linkage unless the gas is over flowing from the bowls. When you see gas coming out from the area around the shaft you need to think about things like the float, needle & seat and possibly the gaskets in between the metering plate and the carb body. Also the shaft hole in the carb base may be worn oversize with the years of use. This makes it easier for the gas to run past the shat but the source of the leak is still elsewhere than the throttle linkage.
Also todays gas has a tendency to turn to vapor at lower temps than the gas of days gone by. The result is that the gas can perculate (vaporize) at a lower ambient temp and then it flows out of the carb bowl running down into the carb venturies when the car sits after running. The gas will hit the closed throttle plates and then run out the side of the throttle shaft producing what appears to be a leak at the throttle linkage. This vapor point problem can be a real PIA but some careful tuning of settings in the carb (assuming the carb is in tip top shape) can fix the overflow.
Also todays gas has a tendency to turn to vapor at lower temps than the gas of days gone by. The result is that the gas can perculate (vaporize) at a lower ambient temp and then it flows out of the carb bowl running down into the carb venturies when the car sits after running. The gas will hit the closed throttle plates and then run out the side of the throttle shaft producing what appears to be a leak at the throttle linkage. This vapor point problem can be a real PIA but some careful tuning of settings in the carb (assuming the carb is in tip top shape) can fix the overflow.
It might be leaking out of the throttle shaft but if it is the source of the leak is not at the throttle shaft. When the car is sitting still there is no gas anywhere near the throttle shaft / linkage unless the gas is over flowing the bowls. When you see gas coming out from the area around the shaft you need to think about things like the float, needle & seat and possibly the gasjets in between the metering plate and the carb body.
Also todays gas has a tendency to turn to vapor at lower temps than the gas of days gone by. The result is that he gas can perculate (vaporize) at a lower ambient temp and then it flows out of the carb by running into the carb venturies. the gas will hit the closed throttle plates and then runs out the side of the throttle shaft and producing what appears to be a leak at the throttle linkage. Check the accel pump first that is a prime candidate but other things can be at fault.
Also todays gas has a tendency to turn to vapor at lower temps than the gas of days gone by. The result is that he gas can perculate (vaporize) at a lower ambient temp and then it flows out of the carb by running into the carb venturies. the gas will hit the closed throttle plates and then runs out the side of the throttle shaft and producing what appears to be a leak at the throttle linkage. Check the accel pump first that is a prime candidate but other things can be at fault.
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Drifting
Joined: Jul 2005
Posts: 1,615
Likes: 37
holley 4160 327 fuel smell
It might be leaking out of the throttle shaft but if it is leaking out there the source of the leak is likely not at the throttle shaft. When the car is sitting still there is no gas anywhere near the throttle shaft / linkage unless the gas is over flowing from the bowls. When you see gas coming out from the area around the shaft you need to think about things like the float, needle & seat and possibly the gaskets in between the metering plate and the carb body. Also the shaft hole in the carb base may be worn oversize with the years of use. This makes it easier for the gas to run past the shat but the source of the leak is still elsewhere than the throttle linkage.
Also todays gas has a tendency to turn to vapor at lower temps than the gas of days gone by. The result is that the gas can perculate (vaporize) at a lower ambient temp and then it flows out of the carb bowl running down into the carb venturies when the car sits after running. The gas will hit the closed throttle plates and then run out the side of the throttle shaft producing what appears to be a leak at the throttle linkage. This vapor point problem can be a real PIA but some careful tuning of settings in the carb (assuming the carb is in tip top shape) can fix the overflow.
Also todays gas has a tendency to turn to vapor at lower temps than the gas of days gone by. The result is that the gas can perculate (vaporize) at a lower ambient temp and then it flows out of the carb bowl running down into the carb venturies when the car sits after running. The gas will hit the closed throttle plates and then run out the side of the throttle shaft producing what appears to be a leak at the throttle linkage. This vapor point problem can be a real PIA but some careful tuning of settings in the carb (assuming the carb is in tip top shape) can fix the overflow.
Melting Slicks
Joined: Aug 2004
Posts: 2,058
Likes: 554
From: Sun Prairie WI
Steve
Although it is more common on 300HP/Holley configurations with a cast iron intake manifold, you may indeed be experiencing expansion of the gas in the accelerator pump wells from residual engine heat. It will 'pump' the fuel out through the discharge nozzles after shutdown.
Since the heat source is radiant (rather than conduction or convection), you could consider a reflective aluminum heat shield between the manifold and the carb as the 'meat' in a gasket sandwich.
Holley makes such a shield, but it will not fit without modification; bends, joggles, and trimming.
http://www.holley.com/108-70.asp
Summit or Jegs retails them. If you don't want to fool with the modifications for fit-up, perhaps could have Lars make one for you.
Here's pics of my '66 with such a heat shield that cured a similar problem. I did not use the thick gaskets that come with the shield since it raised the height of the carb too high to get a reliable fit for the choke rod from bimetal coil to carb.
Although it is more common on 300HP/Holley configurations with a cast iron intake manifold, you may indeed be experiencing expansion of the gas in the accelerator pump wells from residual engine heat. It will 'pump' the fuel out through the discharge nozzles after shutdown.
Since the heat source is radiant (rather than conduction or convection), you could consider a reflective aluminum heat shield between the manifold and the carb as the 'meat' in a gasket sandwich.
Holley makes such a shield, but it will not fit without modification; bends, joggles, and trimming.
http://www.holley.com/108-70.asp
Summit or Jegs retails them. If you don't want to fool with the modifications for fit-up, perhaps could have Lars make one for you.
Here's pics of my '66 with such a heat shield that cured a similar problem. I did not use the thick gaskets that come with the shield since it raised the height of the carb too high to get a reliable fit for the choke rod from bimetal coil to carb.
Melting Slicks
Joined: Jun 2006
Posts: 2,660
Likes: 7
From: DFW
You guys have done great on my last two questions. I bet you can get three in a row
My Holley 4160 on my '66 327/350 is leaking. Looks like just when I turn the car off ( I know I should just keep driving ) It seems to seep from under the front left side of the carb. It could be leaking from the accellerator pump.
Anybody had a similar problem ?
DFA
My Holley 4160 on my '66 327/350 is leaking. Looks like just when I turn the car off ( I know I should just keep driving
) It seems to seep from under the front left side of the carb. It could be leaking from the accellerator pump.Anybody had a similar problem ?
DFA
Also, have you changed the fuel filter lately? That fitting can be a bear to get a good seal on without stripping the threads. I finally pulled the internal filter and put a big Holley cannister filter in the line to the carb
Racer
Joined: Jun 2003
Posts: 290
Likes: 1
From: Torrington Ct
Sorry about double post. I will immediately advise the moderators that the overflow fence is not working. I did a correction to the first post and ..............awwwww why bother explaining........................
Last edited by hpexpatriot; May 26, 2007 at 10:26 AM.
Racer
Joined: Jun 2003
Posts: 290
Likes: 1
From: Torrington Ct
You may need to play with resetting the float levels and / or installing a new needle and seat. Do some searches ....the retunning for todays gas is in here somewhere. You might need to go to the archives.
Racer
Joined: Jun 2003
Posts: 290
Likes: 1
From: Torrington Ct
Could be they are loose but be very careful: overtightning can warp the carb body and then nothing short of resurfacing the carb body will stop the leaks.
Team Owner
Joined: Oct 2000
Posts: 38,897
Likes: 1,926
From: Washington Michigan
When you remove the pump cover, check to make sure it's absolutely dead flat (many warp over time). Sand it on a piece of glass until the witness marks are even (indicating it's flat) before you re-install it, and be careful when you install the cover screws so you don't snag the edge of the rubber diaphragm and tear it.
Le Mans Master
Joined: Feb 2006
Posts: 6,048
Likes: 5
From: "cutesy" TN
First post 9:14, edited 9:23.
Second (double?) post 9:27.
