Leaking Holley 1920

[HTMLmopars]

A while back I rebuilt the 1920 carb on my brother's 65 Dart. I had just done a refresh on my 67 Valiant's 1920 that had been sitting for decades so I was at least cautiously confident that I could improve a pretty poor starting and stumbling 1bbl. It seems like all the detail work went well, the car starts and runs great, but it just DUMPS fuel out of the bowl.
We found a junkyard unit and put that bowl in the car to see if that would fix it. It improved but wasn't perfect. We replaced gaskets with both homemade and parts store units and nothing solved it, cleaned all the mating surfaces, etc with no luck at all.
The last thing I can think of is double stacking gaskets to try and fill any deformities in the carb body. After that the plan is basically to just find a 2bbl manifold and move on.
Any advice on what route to go?

 

[Rug_Trucker]

Brass,or phenolic float?

 

[HTMLmopars]

Brass,or phenolic float?

Phenolic

 

[Rug_Trucker]

Is it soaking up gas? Also check for trash on the needle halve

 

[slantsixdan]

Most likely, the carburetor body and/or bowl is warped, and/or there is a burr or foreign material on the sealing flange area(s). Doubling or tripling up on gaskets might stop the bleeding.

More detail might wring out a more helpful answer to this one. Exactly where is the fuel leaking? Bottom, sides, particular corner, top…?

All Holley 1920s had—and continue to have—nitrophyl floats. It is a closed-cell foam material, neither brass nor phenolic.

Designing a carburetor with a bowl gasket below liquid fuel level is engineering malpractice.

 

[Rug_Trucker]

Most likely, the carburetor body and/or bowl is warped, and/or there is a burr or foreign material on the sealing flange area(s).

All Holley 1920s had—and continue to have—nitrophyl floats. It is a closed-cell foam material, neither brass nor phenolic.

Thank you Dan. Nitrophyl was the term I was looking for.

Maybe some Permatex blackberry syrup type gasket sealer would help?

I was just looking at 1920 images. Some have brass floats. They may be available for the Mopar 1920's.

 

[slantsixdan]

Maybe some Permatex blackberry syrup type gasket sealer would help?

No. There is no gasket sealer you can use that is adequately gasoline-proof. All of it will dissolve, and that portion of it on the inside will go on to clog up stuff in and downstream of the carburetor that shouldn't ought to be clogged up.

I was just looking at 1920 images. Some have brass floats.

No, sir. There are other Holley carburetors that look similar to the 1920 that have brass floats, but all 1920 floats are Nitrophyl, and there is no other-model brass float that will fit a 1920.

They may be available for the Mopar 1920's.

Nope!

 

[HTMLmopars]

Most likely, the carburetor body and/or bowl is warped, and/or there is a burr or foreign material on the sealing flange area(s). Doubling or tripling up on gaskets might stop the bleeding.

More detail might wring out a more helpful answer to this one. Exactly where is the fuel leaking? Bottom, sides, particular corner, top…?

All Holley 1920s had—and continue to have—nitrophyl floats. It is a closed-cell foam material, neither brass nor phenolic.

Designing a carburetor with a bowl gasket below liquid fuel level is engineering malpractice.

It's been a while since I actually looked at the car but if I remember right, it was leaking near the bottom, maybe more biased toward the left side of the carb.
I'll see if we can get extra gaskets on there to really take up the space.

 

[Rug_Trucker]

I thought that Permatex could handle gasoline.......... "

• Reliable, fast-drying, all-purpose sealant dries to a highly tacky, non-brittle film; remains tacky indefinitely
• Tacky paste for holding cut gaskets in place during assembly; helps seal cut gaskets
• Resists gasoline, oil, antifreeze, axle lube, kerosene, propane and butane; sensor-safe
• Temperature Range: -65°F to 500°F (-54°C to 260°C)
• Suggested Applications: Valve covers, fuel pumps, carburetors, manifold gaskets; seals any rubber, cork, paper or composite gasket

 

[HTMLmopars]

I thought that Permatex could handle gasoline.......... "

• Reliable, fast-drying, all-purpose sealant dries to a highly tacky, non-brittle film; remains tacky indefinitely
• Tacky paste for holding cut gaskets in place during assembly; helps seal cut gaskets
• Resists gasoline, oil, antifreeze, axle lube, kerosene, propane and butane; sensor-safe
• Temperature Range: -65°F to 500°F (-54°C to 260°C)
• Suggested Applications: Valve covers, fuel pumps, carburetors, manifold gaskets; seals any rubber, cork, paper or composite gasket

View attachment 1716257223

I've used the aviation permatex to assist a fuel filler neck gasket before. It's held up for a while.
We had some left over so we lightly tacked a gasket with it but it still wanted to leak.
Gasoline is a pretty good solvent, so it wouldn't surprise me too much if Dan is right.

 

[slantsixdan]

Yes, Aviation Permatex can handle exposure to gasoline vapour and the occasional splash of liquid. Constant submersion in liquid gasoline is a totally different matter.

Keep in mind we are talking about a pot of highly flammable liquid, perched right near a part of the engine (exhaust manifold) which can get hot enough to make an Earth-shattering kaboom. Not the place for eh, it might seal up more or less well enough.

 

[HTMLmopars]

Yes, Aviation Permatex can handle exposure to gasoline vapour and the occasional splash of liquid. Constant submersion in liquid gasoline is a totally different matter.

Keep in mind we are talking about a pot of highly flammable liquid, perched right near a part of the engine (exhaust manifold) which can get hot enough to make an Earth-shattering kaboom. Not the place for eh, it might seal up more or less well enough.

Ahh so it's gasoline *resistant*
There's a reason the car hasn't been driven more than to repark it since this debacle started. With it's new mini starter and a rebuilt carb, it starts great though!

 

[HTMLmopars]

Update: double stacked gasket was a no go. Still leaked.
I'm ready to just drop in a 2bbl that I have laying around. Just need to modify the intake and throttle stuff to work with it