Carburetor Main passage bleeder

[ArtJ]

I would like to see a method of bleeding the main passage on the carburetor
using a permanently installed fitting which would replace the main passage plug and permit
bleeding of the carburetor in a emergency with a hot engine without the
risk of gasoline fumes causing danger of fire or explosion.

The main passage plug would be refitted with a adapter which was normally
closed, but could be opened to a hose barb fitting which via a piece of hose
connects to a second fuel water separator, or similar device.

In this way, the carb could be bleed in a emergency without having to
deal with a hot engine and potential fire.

The separator could be emptied even days later at a safe and convenient
time.

Thanks

[hanleyclifford]

Art - I think this is what you have in mind. It would be necessary to rethread the carb body for 1/8" NPT. If you like it I'll get the McMaster number. Regards, Hanley

[ArtJ]

Hanley you are truly amazing. The things you can come up with astound.

The picture is not entirely clear. Which parts are necessary? The picture
does not appear to be a carburetor installation.

Thanks!

Art

[ArtJ]

On a second glance, it appears that only the "faucet" part is required,
along with a adapter of some sort? from its lower threaded part to a hose barb.

Is this correct? I would love the McMaster Carr part nos.

Thanks again

Art

[ArtJ]

Hanley Do you think there would be sufficient clearance to retap the passage without disturbing
the main jet or its seat?

Regards,

Art

[hanleyclifford]

Art - I am actually using the valve as a block coolant drain. The McMaster number is 5049K1. Go to their catalogue and you might see something even better for your proposed application. I see no problem tapping out that hole but I have never tried it. Do you have an old carb body to practice on? Regards, Hanley BTW Thanks for motivating me to take that picture - notice the small antifreeze leak!

[ArtJ]

Hanley,

I do have a old carb body, and I just looked at the passage, seems as though
there is sufficient clearance to tap it out. Where would I purchase a NPT
1/8 inch tap? I have ordinary taps, but not NPT.


I will peruse McMaster Carr

Regards,


Art

[hanleyclifford]

McMaster Carr has an amazing tool section.

[ndutton]

Art,
Since there's been no mention of a pump, the drain would by necessity be a gravity type. That means the reservoir would need to be lower than the carburetor and the reservoir would need to be vented to accommodate the internal volume displaced by fuel.

What about some means to impart a small vacuum on the reservoir? That would allow mounting it above the carb and eliminate the need for venting. Something like the ever so popular outboard type priming bulb would do. Give it a few squeezies, open up the new main passage valve and whoosh, just like a mini vacu-flush head.

[ArtJ]

Guys

I just spoke with mcmaster carr. They said that the 5049k1 which hanley
described is only recommended for use with water. They have a high flow
valve just below on same page , but it is 3/8 Nptf. Too bad because
it has a barb already on the port. it is also much bigger

They also mentioned that tapping out the 3/8 inch NF to 1/8 NPTF would
leave some of the original threads in place and would probably leak.

They identified drill size Q 332 mm and the tap needed is their pn 2525A169


They suggested trying a auto parts store for a valve.

I asked them for a plug as well to replace existing passage plug, all they
came up with is a 1/2 inch bolt. Which wouldn't do by itself.

[ArtJ]

Art,
Since there's been no mention of a pump, the drain would by necessity be a gravity type. That means the reservoir would need to be lower than the carburetor and the reservoir would need to be vented to accommodate the internal volume displaced by fuel.

What about some means to impart a small vacuum on the reservoir? That would allow mounting it above the carb and eliminate the need for venting. Something like the ever so popular outboard type priming bulb would do. Give it a few squeezies, open up the new main passage valve and whoosh, just like a mini vacu-flush head.

Hi Neil,

My plan was to use the already mounted priming bulb as I already do
when removing the passage plug and flushing.

I was also thinking, like you, that the bleed would need to be opened
on the separator/reservoir.

The problem now is getting something similar to what Hanley found
that likes ethanol fuel and can be tapped to a good fit.

Regards

Art

[ndutton]

Pipe taps are pretty common and any decent hardware store should have one on the shelf. No boutiques!!

I don't know for sure but I have a concern over the weight and leverage of a valve hanging on threads tapped into the bowl casting with even normal engine vibration.

[ArtJ]

Hi Neil

Maybe the valve could be mounted down stream from the carb and
just have a hose barb adapter.
I just spoke with Zenith customer service. He was thinking about tapping
the passage plug with a smaller diameter threaded hole. That way the
original passage threads are not compromised. Course that would have
to be adapted to some small hose barb/ line and a valve.

Art

PS Zenith is getting back to me with pn price and availability of passage
plugs and washer. I will post when I get them

[Dave Neptune]

Vent

Note, the bowl is already vented or the carb would not work.

In doing so you are adding another place to leak, maybe not a good idea. That's why I removed my Adj. jet set up, it was always damp from fuel.

Dave Neptune

[ndutton]

I was referring to a vent for the new drainage reservoir rather than the carb and agree that it's undesirable but without the reservoir vented it will become pressurized as fuel enters. Same thing as a miniature version of a fuel tank. Can't put fuel in the tank without relieving the resulting displacement pressure.