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Carb leaking

 
Old 04-14-2019, 03:29 PM
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70GHH
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Default Carb leaking

One of the gaskets is leaking on the lower front right side of my carb (circled in the picture). Before I start taking apart something that I am under qualified to do I thought I'd check with the forum. Can I take the end of the carb off and then tighten up this connection? I don't see how to tighten this up any other way.
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Old 04-14-2019, 03:42 PM
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2009stanger
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I believe that part is called a diaphragm. Mine leaked at another part of the carb. I bought a rebuild kit from either Summit or Jegs. It will come with that part and all new gaskets. I found a video on YouTube and just followed along. I would suggest pulling the carb and doing the same. A speed shop could also rebuild it, but of course thatíll be more expensive.
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Old 04-14-2019, 03:45 PM
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If I understand your picture, your leak is at the power valve (or what some call the accelerator pump).

Also, if I understand your plan, you plan to remove the float bowl to get access to it, but without removing the carb. Oof.

I think, given your admitted lack of experience with this, I would advise against it. Lots of opportunities for expensive problems to occur.

How bad is your leak?

I'll add this to it - that appears to be a 3-digit date code on the air horn, so is it the date-matching carb on a highly original car?

If so, and it hasn't been gone through in awhile, I would consider sending to one of the pros that rebuild these classic carbs. The other gaskets may not be far behind. Also, once you pull a float bowl, it may never seal again unless you go through all the gaskets, which is a great time to have the entire carb gone through.

Last edited by Easy Rhino; 04-14-2019 at 03:49 PM.
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Old 04-14-2019, 03:49 PM
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Probably the accelerator pump diaphragm is leaking. You can take the carb off for a look or you can simply remove the four bowl screws and pull the assembly off.

The four bowl screws should only be snugged when you re-install the bowl and metering block. There are different gaskets for the metering block/air horn. Make sure you get the right one for your carb. Get the black ones that don't shrink. I think there are blue ones as well. If you get lucky and your old gaskets don't shrink or dry out or leak, you can re-use them.

The accelerator diaphragm should be replaced. It only costs a few bucks.

Ham fisting the screws on a Holley is not the correct way to seal them up but it is the best way to destroy them.

Last edited by MikeM; 04-14-2019 at 03:51 PM.
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Old 04-14-2019, 03:50 PM
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It's odd. It wasn't leaking last wekend, now it's weeping quite a bit. I don't mind pulling the carb. I twas rebuilt about six years ago. Could that gasket dry out that quickly?
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Old 04-14-2019, 03:53 PM
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Yes it could.
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Old 04-14-2019, 03:55 PM
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Originally Posted by 70GHH View Post
It's odd. It wasn't leaking last wekend, now it's weeping quite a bit. I don't mind pulling the carb. I twas rebuilt about six years ago. Could that gasket dry out that quickly?
The diaphragm gasket doesn't dry out. The rubber diaphragm gets a hole i it and the gas runs out through the pump lever.
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Old 04-14-2019, 03:55 PM
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If you do not drive them they will leak,but if it dried up just watch it and if you smell gas from inside the car rebuild the whole carburetor.
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Old 04-14-2019, 04:17 PM
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Take off the carb and tighten the four screws that hold this accelerator pump assembly. Then put the carb back on. MAYBE install a new and more pliable carb gasket between the carb and intake manifold while you are at it. They harden with time.

My carb also leaks in this area and has for some time, since I don't drive it very much. When car heats up the leak stops, and then after sitting for a week, the leak opens up and drains some gas. I have just lived with it...........but I plan to pull and completely overhaul the carb later this summer. It has gone over 24 years without a rebuild.

It is an easy fix..........even if you have to replace the diaphragm like Mike states. But then you have to buy parts.

Larry
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Old 04-14-2019, 04:26 PM
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Just note the screws holding the accelerator pump on should be clutch head. So if you don’t have any clutch head bits get some or your project will stall very quick.
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Old 04-14-2019, 05:37 PM
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Originally Posted by Nowhere Man View Post
Just note the screws holding the accelerator pump on should be clutch head. So if you don’t have any clutch head bits get some or your project will stall very quick.
Good point.

It is possible to shove a #2 Phillips bit in the clutch head and get the screws tight enough.

My money is still on a ruptured diaphragm.

Last edited by MikeM; 04-14-2019 at 05:37 PM.
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Old 04-14-2019, 05:58 PM
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It is a possibility that the screws securing the accelerator pump are just loose or the bowl gasket has shrunk (especially if cork) and you can tighten the screws and be good to go. I would try torquing the screws first (must remove the carb to torque the accelerator pump screws unless you have a special screw driver). Minor adjustments and gasket replacements are not difficult.

Here is all of the information you need from the Holley web site - https://www.holley.com/support/carburetor/ - It won't make you a tuning expert, but will save you a lot of aggravation and a little money.
I highly recommend following the torque sheet for the fasteners to reassemble it.

I won't get into the type head on the screws, only recommend you use the correct bit in the torque wrench / screw driver. You won't believe how many Holleys have been trashed by the tighten it by feel or just a little more. Do it right, and you won't cry!!!

Ron
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Old 04-15-2019, 01:14 AM
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Originally Posted by R66 View Post
It is a possibility that the screws securing the accelerator pump are just loose or the bowl gasket has shrunk (especially if cork) and you can tighten the screws and be good to go. I would try torquing the screws first (must remove the carb to torque the accelerator pump screws unless you have a special screw driver). Minor adjustments and gasket replacements are not difficult.

Here is all of the information you need from the Holley web site - https://www.holley.com/support/carburetor/ - It won't make you a tuning expert, but will save you a lot of aggravation and a little money.
I highly recommend following the torque sheet for the fasteners to reassemble it.

I won't get into the type head on the screws, only recommend you use the correct bit in the torque wrench / screw driver. You won't believe how many Holleys have been trashed by the tighten it by feel or just a little more. Do it right, and you won't cry!!!

Ron
No. the accelerator pump diaphragm and the gasket are one piece. MikeM has the most logical answer, the diaphragm ruptured and is leaking out the pump arm. The gasket surface in this case is the same as the diaphragm, nitrile, etc.

This is an easy fix. 10 min. if you have the tools and the parts on hand. Any auto parts store should have the part, 5-6$.
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Old 04-15-2019, 11:02 AM
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dcamick
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Can easily be confused with a simple float bowl screw nylon washer replacement..........I had the simple problem .........easy fix....or maybe not!!!

Bought the diaphragms and never used them...................

https://www.ebay.com/itm/Holley-Floa...53.m2749.l2649

Last edited by dcamick; 04-15-2019 at 01:50 PM.
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