Fuel Leak all over intake manifold

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1970Dart198

1970Dart198

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Hello, I have a holley 1920 model carburetor on my 198 ci slant six.

I had a previous 1920 with which I used the float bowl cover, and a new gasket to hopefully stop a slow leak onto my intake manifold.

It turns out, it does the exact opposite and there's MORE fuel leaking out of the carburetor.

If I put my hand underneath the bowl cover, there is gas all over my fingers. I know there's a check valve in the accelerator pump and it starts leaking out if the accelerator pump is compromised, but i looked down into the carb and operated the throttle and there is a strong, healthy shot of fuel.

I put on a reasonably straight, and not all that warped float bowl cover, in place of the old one that was warped, with a new gasket and it leaks even worse.

Any ideas on a good gasket type to seal the float bowl? I used up my float bowl gasket, is it reusable? Its less than a week old so I would think so.

Thanks!
 
If you are sure the new float bowl cover is straight/true and not warped, you may have bent mounting points. I have heard about them getting bent from those screws getting over tightened trying to stop a fuel leak.
 
You can have a leak in the accelerator pump diaphragm and still have a good strong accelerator pump shot. The diaphragm's back side is exposed to the rod hole in the back of the pump area, and a small pin-hole leak in the diaphragm will leak out of there, but the diaphragm will still be substantially intact and be able to push a full shot into the carb throat. So you have not eliminated a pump diaphragm leak yet. This was exactly the type of a leak like I had in my 1920 carb. You have to pull off the bowl and then remove the jet assembly to check the diaphragm.

And, yes the bowls get warped/distorted so that is another potential source of leaks. If you did not use any sealer on the gasket it ought to come off intact; if it is cork, it might shrink when it dries. I have been threatening to try Permatex Permashield 85420 the next time I need to put on a 1920 bowl gasket, but have not used it yet, so I am just pointing you in a direction that might work; it is gas and oil resistant (not silicone). There is no real pressure on the bowl gasket so that helps. (Follow the instructions to let it dry for the solvent to evaporate before assembly.)

I alos have had issues of the bowls screws loosening up a bit; have not tackled a thread lock for that, but will probably try blue Locktite, or a small amount of #1 Form-a-Gasket on the threads if that does not work.
 
I cut out my own gasket with a thicker material a friend gave me. I'm not too fond of the holley design, but it gets the job done! I put a bead of 30 weight oil around the mating surface on the carburetor, as recommended by Aggressive Ted in a previous forum. The main sign of a leak for me was the smell of gas when it would leak out onto the hot manifold and quickly evaporate.

The float bowl gasket material that comes in the rebuild kits from GP Sorensen or Standard Hygrade arent all that great. Getting any of that gasket sealant into the carb metering block would gum-up all the little check balls and passageways.

I'll see how this new gasket material holds up.
 
Let us all know how it works and the material if it does work better; that would be a useful fix.

Yes, anything could plug up the jets; you just have to not slob it all over!
 
Best of luck. That's why I switched from a 1920 to a 1945. Just not too fond of the idea of fuel dripping onto a hot manifold because of a gasket being below fuel level.

There's a glass float bowl cover in existence that came on some of the older 1904 models, which doesn't warp like the metal version. But, there again, it's glass. One rock thrown by the fan into the carb....poof.
 
Well, after driving it and leaving the car for a few hours, I opened the hood while crossing my fingers to find GAS ALL UNDER THE BOWL AGAIN!! Heck, I even saw a drip of fuel from under the bowl. I've had it with this 1920, the car will run and drive, but it bogs under acceleration, my mileage is out for lunch, and the garage reeks of fuel after I shut it off.

My plan of action, take off the carb and leave the manifold cleaned up for the 4 1/2 months I am away studying abroad in Vienna, Austria. When I get back I'm going to order a Carter BBS. I like the design of the BBS, less prone to leaks, and the availability of FLOATS!

The 1920's been a good companion for my little 198 ci, but the ever constant drip of fuel, and buying rebuild kits is starting aggravate me.

Thoughts? Opinions? I believe a number of people have made this turn?
 
"Thoughts? Opinions?"
Did it leak inside the engine also?
Fire extinguisher a must.
 
Thats the first thing I put in my box of chemicals and liquids in the trunk when I first got the Dart! Damn my car barely even farted when I first got it. Look at it now! This forum has worked wonders on the overall drive-ability of the car.
 
Well, the 1920 that was on my '73 Valiant was the original with 49K on it. It was covered in grunge and appeared to have never been apart. It ran ok most of the time but sometimes would barely run after a restart, or it would experience a huge stumble occasionally even when hot.

Finally I started smelling a whiff of gas and it was the accelerator pump "hole". That great idea about ruptured pump diaphragms dumping fuel on a hot engine isn't just a 1920 thing either, most Holley carbs are like that. That and the float bowl gaskets are why I won't use a Holley of those types.

I found a Holley 1945 off an '84 Van. I modified it to use an actually base idle screw instead of the Idle Stop Solenoid, rebuilt it and it works fine. There are no gaskets below fuel level, it uses a common cup-style accelerator pump, and also a center-hung brass float.

The BBS should be great but try to find an unrebuilt original instead of a parts-store carb.
 
the BBS listed is a good carb. but DO watch the two long screws if you over tighten them the castings will warp.
 
I have never worked on a BBS but have read (from someone who tends to know) that the bushings around the throttle shaft tend to commonly be worn out and need to be re-bushed.
 
You may want to check or replace your float. If it's old and saturated it won't float and will not close off the fuel supply. It will cause the symptoms you listed above.
 
take the 1920 bowl of and run it across some 150 grit sandpaper on a piece of glass (flat). Keep rubbing until you see fresh metal all around the bowl. The bolt tangs always bend on these bowls and possibly bend so much that they bottom out on the threaded ears, never compressing the gasket. I looked t a rebuilt one from Autozone and the bowl tabs were bent already, touching the body ears. I rebuilt mine and it worked fine after the accelerator pump was shooting gas out the weep hole,,how safe was that?
 
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