Carb questions

[Steve Nau]

I am trying to figure out why one of my Solex 32 PBI carbs smokes after the engine has run for a bit. The engine has about 300 miles on it since rebuild and the problem has been consistent since, The engine starts easily when cold but after running it seems to get flooded which I believe ties in with the smoke.
My guess is gas is dripping after the engine is turned off. First guess was the float was causing it. Adjusting the float didn't help. The other carb doesn't have the problem so I moved the float from that side but the problem is still on the same carb so I don't think it is a float problem.

I removed the carb today and noticed someone has scratched "KSHORT" on the side of the offending carburetor. Any idea what that might mean? Pic attached.
Any other suggestions?

[Alan Hall]

Not sure what you mean by "carb smokes", is it smoking while the engine is running or after shut down and is the "smoke" coming out the top of the carb or where?

[Steve Nau]

I guess a better description would be fuel vapor?
If you look down the throat of the carb with the filter off after you shut off the engine the vapor is down the throat.
The "smoke" is not there when the engine is running.

[Alan Hall]

Thanks for the clarification, it does sound like some fuel is leaking down onto the hot valves and being vaporized. Since the engine is shut off at that point it would seem that it must be leakage from the float chamber but you indicated that the float level is OK there must be a leak path from the float chamber to the throat of the carb. I will look at a diagram and see if any possibilities jump out or perhaps others may have some insight.

[Alan Hall]

One thing that might be a problem is the emulsion tube well, item 63 in the exploded parts diagram. It is a pot metal part that is often broken at the top by someone trying to over tighten the air correction jet (item 65), When it breaks it requires the well to be replaced, The well is a press fit into the carb body and at this point the only replacements are either used or reproduction parts. If the press fit were too loose perhaps they would leak gas where it fits into the carb body. It might be appropriate to discuss this with one of the carb rebuilders or perhaps they might comment here. Hmm....sorry the diagram is upside down don't seem to be able to rotate it!

[Steve Nau]

The emulsion tube well (63) appears to be brass not pot metal and it appears to be snug in the carb body.
I notice that when the jet (65) is screwed in there is a gap between it and the top of the well. Should there be a fiber washer under the jet to seal the gap?
I don't see one in the diagram or the rebuild kit.

[Steve Nau]

Here is another pic

IMG_3067.jpg (1.56 MiB) Viewed 1272 times

[Steve Nau]

The well in the other carb is pot metal and the jet fits snug at the top so maybe this is the problem?

[Steve Nau]

According to 356 Carb Rescue brass emulsion wells were used on the 40 PBI carbs.
Given that there is a hole in the top of jet (65) would it matter if it screws down fluss against the well?
If I remove the emulsion tube (64) it will screw all the way in but not sure if that matters.

[Alan Hall]

The brass emulsion tube well in your 32pbi is an aftermarket part. The 40pbic wells were brass but were a totally different design and not interchangeable with the 32 well. It does not matter if the air correction jet is not fully down on the well, it seats against the emulsion tube itself and usually sits slightly above the top of the well. That said, it does appear to be abnormally high on the brass well in your photo, which perhaps reflects differences between the aftermarket brass piece and an original. I have no experience with the aftermarket parts so don't know if this is the likely source of the issue. Maybe a call to Carb Rescue might give some insight on the quality of these aftermarket parts, and how well they fit the carb body which, as I said, is supposed to be a press fit to assure no leakage at the interface. I suppose if the fit was too tight, pressing the brass piece in might have cracked the pot metal carb body at that point which could be a source of a leak.

[James Davies]

From your photos, that's not a 32 PBI. Probably a 32 PBIC? Different carbs. Yours has a 1-piece body with a separate lid. The 32 PBI had a 2-piece body with a separate lid.

Knowing your carb will help you get the right diagram and parts needed.

[Tony Proasi]

Check the needle and seat.