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NCC Forum Home Page -> NCC - General Discussion -> Appears my Carb Leaks, any Suggestion as where it Leaks and How to fix?
Post Info TOPIC: Appears my Carb Leaks, any Suggestion as where it Leaks and How to fix?
jim larson


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Appears my Carb Leaks, any Suggestion as where it Leaks and How to fix?
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Take a look at the photos. One shows oil.  Other shows where I wiped up similar pools of oil.

I think it is oil from the MO I add to the gas or from the blue stabelizer that I added for winter storage.

I think it is leaking and the gas evaporates and the oil remains.  Looks like I m should try a new manifold gasket and maybe a gasket on the accelorator pump and maybe a thin gasket between the Stainless Steel baffel and the base of the trottle plate.

What about adding a thin layer of the high temp RTV to help seal things up?

Thanks for you opinions in advance.



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Jim L

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Your floats were not sealing 100% and slowly leaking over time. If you run it, check the next day or so by pulling off the carb and seeing if there is gas on the manifold / carb gasket. My eddy was doing this.

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John E - Rogers, MN

Instructions? All I need is the exploded view.
70 El Camino soon to be ls1/t56
64 Malibu SS
jim larson


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So the though is that if the floats don't seat close the gas off completey, then the gas overflows down the throttle body and works it way outside?

I am a little inexperienced in the operation of the carb.  So gas can make its way though the throttle body when the car is not running and the fuel pump is not operating?  Thanks.



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Jim L

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On mine, the floats would slowly leak over time from the fuel pressure in system when I shut off and dribble fuel down the inside if the carb and it would wick around to the base gasket. Mine base gasket was saturated with gas when I took the carb off.

You can always take the carb off and see if there was a trail that developed.

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John E - Rogers, MN

Instructions? All I need is the exploded view.
70 El Camino soon to be ls1/t56
64 Malibu SS
jim larson


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Thanks, I think I understand now.  The floats would take on a little gas because they leak, so the pressure in the fule pump/line would force a little gas into the carb since the floats could not close the needle valves completely, so gas would overfow until the presure no longer exists.

I will pull the carb and check, if there is evidence of gas in the floats that would mean they need to be replaced  and if the floats are dry that would mean I would have to replace the needle vlaves, right?

What about driving the car for a while, then shut it off, and remove a sight plug, Should gas drain out of this plug instead of flowing into the main body?



-- Edited by jim larson on Saturday 28th of April 2012 09:08:13 AM

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Jim L

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jim larson


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Started and drove the car a little.  Fuel level in the bowls the same 1hr after the drive as just before the start.  Didn't drive much, so no new accumulation of oil.

 

Since I have a heat riser valve, could he exhaust that is being forced up under the carb and out the drivers side exhaust pipes be transfering oil residue to the gasket and that leaking down around the outside of the intake?

Carb doesn't appear to leak anywhere when it car just sits.  The oil residue appears after driving it for 30-60 min.  I wonder if a fue bowl or accelorator pump gasket could leak a little when car is running and there is pressure in the fuel line?



-- Edited by jim larson on Saturday 28th of April 2012 06:31:33 PM

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Jim L

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jim larson


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Well I went out to look at the carb/ intake and there again was the oil/gas in three 4 spots on the intake.  Gasket between the throttle plate and baffle looked wet, so I took the carb off.  Gasket all wet along with the SS baffle being wet.

So I guess that would mean fuel running into the main body and working its way on the the SS baffle and  to the outside.  Think I have the wrong gasket between the throttle plate and SS baffle, so not sure if that would allow gas to collect on the baffle and work its way to the outer edges of the gasket and then leak to the outside.  I had a gasket for I think its called something like squarte port., as it has a large square cut out of the center.  Think the gasket is suppose to have 4 holes to match the bottom of the  throttle plate.  Maybe this is the problem?

Well I have the floats submerged in gas to see if they take on any gas.  

Here I go thinking again, if the floats are goo and are  shutting off the needle valve  and the needle valve was bad, would that allow gas to seep into the main body and down on to the SS baffle?

Thanks, this is a pain

Here is a photo of the gaskets.  Also after an hour of being submurged in gas the float have not taken on any gas.



-- Edited by jim larson on Sunday 29th of April 2012 01:46:54 PM

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