Needle Seat Gasket Surface

[von]

  I have trouble on some carbs getting the needle seat to main body gasket to seal to the main body. The gasket surface of the main body on some gets eroded and or chewed up over the years. After getting the needle and seat by themselves to hold a vacuum, I rig up a fuel line stub and vacuum pump but won't hold a vacuum then on some carbs even with the paper seat to body gasket (worse with the metal gasket) . Is there a better gasket available or a spot face bit available to surface the gasket surface of the main body at the needle seat?

[omaha]

that is a good question. maybe there are some alternatives like plastic (or similar.)
I guess a tool could be made. (small lathe..?)

[Cliff Ruggles]

Most of the problems we see in that area are tiny peices of the coating from an old gasket left in place. 

I hit the surface area with the bead blaster if I see any irregularities with it.  In almost all cases that is all that is needed.

It's also pretty easy to leave an old gasket it place and not notice it.  Sometimes they stick pretty hard.  Use care when removing them so you don't damage the sealing surface.....Cliff

[von]

Thanks. I always make sure the old gasket is all gone with a magnifying glass and penlight. I sometimes see scratches and gouges in the metal though from I assume previous gasket removals.

[Cliff Ruggles]

Yep, I always pressure test them if I see any sort of irregularity with the gasket surface. 

The repair options are many.  We can "spot face" them here.  I also have had good success using a slightly thicker fiber washer under the seat, but this is a last resort as it raises the needle up some.

Some really old units will be pretty "rotten" in the threads and around the seat.  I've applied a light coating of Marine Tex to some really bad ones and got them to seal up just fine. 

For the very worst ones, a new seat and threads has to be pressed in.  This involve considerable machine work and we avoid this repair due to the expense......Cliff