Carb question: dripping fuel on shut off....

[BattlestarGalactic]

Ok, the rear carb on my pickup is dripping after shut off, drowning it and making it very hard to restart.   I checked float levels, good.  I replaced needles/seats as I found the o-rings were bad.  Still dripping.  I pulled that carb, flat filed the main body and replaced metering gasket.  Still drips.  UGH!!!

I've had carbs do this before, but I've never had one continue to do it even if I did my typical fixes like mentioned above.  With three vehicles with quads on them, it is not uncommon for a random fix every few years.  Strangely, the blower car's 660's have lived for over 10 yrs now with not so much as a screwdriver touching them and it sits for 7 months out of the year in storage.  Note, when I did pull it off(before starting), the front bowl was very near empty, the rear was still full when I tipped it over to drain them before pulling the bowls off.

This is a 1850-6 600 Holley.  What channel could be draining the fuel out of the front bowl just sitting there?  It's not over pressurizing the needle/seat, as I've pulled the sight screw and it was still down below and it was still dripping fuel.  I'm boggled?

[Lg57]

leaking around/thru the power valve?

[shady]

if it's leaking while shut off, it's most likely also leaking while running. My vote also the PV.

[BattlestarGalactic]

Ohhhh, that makes sense.  I was trying to figure out how gas could get through, but the PV makes sense.  It likely is in as bad a shape as the o-rings on the needles!  I will be going out shortly to pull it off and replace it, and will report back.

Thanks guys.

Oh, ya, the 660s don't have PVs!!!   Guess that is why they never leak down!!

[BattlestarGalactic]

Well, plan B.  Didn't have a new one, but tested a second hand one in the spare parts box.  Same issue.  Guess I will hit summit for a couple new ones and try again.

[Drew Pojedinec]

Just plug the pv vac channel and retest.  that'll isolate it to the vac well and it'd have to be pv, pv gasket

[GerryP]

Where is it leaking from?  Are you able to observe the drip or leak as it is occuring?

[fryedaddy]

what kind of fuel are you running.and does it only happen after a long drive.

[BattlestarGalactic]

Just get a smokey mist from primary throttle bores in the one carb.  No real drip to be seen.  It happens as soon as you start and shut it off.  You don't have to wait.

I do have some plugs, and i used a new gasket so I know that wasn't an issue.

[Drew Pojedinec]

Fun Fact, with an assembled carb, you can vacuum test the PV well.

In this scenario another good place to vac test is the accelerator pump channel in metering block.

[6667fan]

Larry, I have flat filed the carb face and thought it was nice but still had a leak. So I brought the body down the street to the machine shop. He put it on his table and it was still off .010 plus.  After he did his thing it was all set.
Hope you get lucky with the pv seal.

JB

[BattlestarGalactic]

I have machines available that i can mill it but with a large flat file it is way closer then it was.  I've never had one be so finicky.

It had blue gaskets, so I've been through this one before.  The front carb is still fine, this one?  I'm getting another quick kit from summit as a start.

[wayne]

Check for a hole in the float make sure the spring is under the float this wont drain the bowl but will give trouble like your having.If the seat cant close all the way.

[BattlestarGalactic]

Pretty sure I have black plastic floats in all my carbs, so no chance of sinking.
If it was overflowing, it should be coming out the sight hole, which it is not.

[C6AE]

Pretty sure I have black plastic floats in all my carbs, so no chance of sinking.
If it was overflowing, it should be coming out the sight hole, which it is not.

I have had black plastic floats "sink"
very frustrating, when I disassembled to check it out they would dry out enough to float again for a day or two.
I had to weigh them on a gram scale to prove it.