Carburetor gasket replacement

[gregsails]

It's been 5 years since I had my late model, 4 screw carb apart for cleaning. I'm looking at it and for whatever reason last time I dressed the big gasket with Permatex Aviation gasket maker. Don't remember why. Is that necessary or should I use the gasket only?
Thanks
Greg C30 sail 694

[GregH]

Just the gasket should be enough if the two faces are flat/true. maybe you added some as a belt & suspenders thing? Or maybe you had a small air leak ( especially at the pointy end where the 5th bolt is now used)?

[GregH]

hey, its the Cdn Contingent this morning!

[Dave Neptune]

No permatex, bare gasket only. If the faces have a gap, lite honing using fine "wet-dry" on a flat surface like glass will help. The part that needs to be sealed inside is the "emulsion well" in the center of the bowl or the carb will be way off.

Dave Neptune

[gregsails]

Thanks Dave. Glad to see your still active

[Al Schober]

Agree that sealant should not be required.
Having said this, I usually put sealant on one side just to hold the gasket in place during the next disassembly. Transmission cover, I bond it to the cover. Valve cover, ditto. Makes reassembly much easier.

[gregsails]

Dave Neptune

So Dave, I fact I do have some worping between the faces that I will try to minimize. What is the emulsion well? And why is it so important?
Thanks Greg

[Dave Neptune]

The Emulsion well is where the fuel is first started mixing with air. The vacuum of the engine sucks air into the well to mix with the fuel from the main jet before the "mix" is directed to the venturi in the throat of the carb to be further mixed with the air going through the carb. This "mix" must be correct for proper burning in the cylinders.

The "E-well" is the protrusion in the center of the float bowl toped by the "air jet" that regulates the air going into the well to be mixed with the fuel (the brass tube with holes in it) from the main jet just below the well. The top of the well must be sealed via the Hole in the gasket to control proper fuel mixing. The air for the well that travels this path is drawn from the throat of the carb to balance the carb mixing across the RPM (load) band.

If it leaks the carb will not work properly causing loss of economy, smooth running and power.

it is why you should always use a fresh gasket for a good crush of the gasket creating a proper seal. Check the old gasket for a full circle indentation in the center meaning it was a good seal.

Dave Neptune

[JustinAlenScott]

Thank you, Dave, for talking me into buying a new gasket. Although I may reuse the flange mounting gasket. Stay tuned for my upcoming carburetor question.

[Dave Neptune]

Justin, a trick on carb gaskets that I use when tuning a carb IE disassembling and assembling in a short period of time or when I can't get a fresh one right away is as follows. Spray with WD-40 until wetted, place in a baggie and let it sit in the sun for an hour or so. The gasket will "swell" a bit and can be re-used a few times. However for rebuilding and assembling for continued use I always try for a new gasket.

Dave Neptune