Test needle valve?

[70Crew]

I am trying to troubleshoot the source of gas in my oil. One of the potential sources, it sounds like, is a sticking needle valve allowing the carb bowl to overfill, causing fuel to pour down the manifold. What is the best (or easiest) way to check and see if the needle valve is operating correctly?

1600 SP motor, stock solex 30 Pict 3 carb rebuilt by Volksbitz.
_________________
1970 Crew Cab

[anthax]

Take the carb of the engine, take it apart and pour liquid through it.
I piece of hose, a small funnel and a small container of water.
Fill up the hose with water, hold the needle vale shut, use mouth to try to blow the water in to the needle valve.
If water pours through, it's bad.

[mikedjames]

Depends on the needle valve design, if you can get the needle out of the valve and you can see any ring of wear on it it is suspect. This leaked in a Weber...

_________________
Ancient vehicles and vessels

1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.

1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy

[[email protected]]

the Viton tipped ones seal much better.
_________________
It's just advice, do whatever you want with it!

Please do NOT send me Private Messages through the Samba PM System (I will not see them). Send me an e-mail to john at aircooled dot net

"Like" our Facebook page at
http://www.facebook.com/vwpartsaircoolednet
and get a 5% off code for use on one order for VW Parts ON OUR PARTS STORE WEBSITE, vwparts.aircooled.net

[70Crew]

OK so I tried the water test. I don't detect any obvious leaks with the valve closed, although there's really no way with this method that I would identify really small leaks.... Maybe it is just the big leaks we are looking for? The only other think I noticed, when I close the valve and blow on it, the plunger does not readily pop out just with that pressure, I have to touch the bottom of the plunger to knock it loose and get it flowing. Since the car seems to run fine, I am assuming that is normal? Really what I am trying to eliminate is the possibility that the needle valve is sticking open or not closing all the way, so minor sticking when closed shouldn't be causing any overfill issues, right?
_________________
1970 Crew Cab

[70Crew]

Actually, I just got a little more scientific and don't think I have a sticky needle valve. I set my compressor to 5 psi and hooked it up to the inlet barb. That is enough pressure to open it. That much pressure also does not leak past the needle when I hold the plunger closed.
_________________
1970 Crew Cab

[modok]

What I used to do was hold carb upside-down, suck on it, stick tongue over barb, see if it holds suction.

When you are young you can drink gasoline, because you are invincible, of course.

(Probably would use a vac pump now)