Carburetor running rich after rebuild

[WileE]

Cleanliness is paramount in a carb rebuild. Did you ensure the idle air bleed holes are not clogged or blocked ?

 

[gthumb]

Like stated previously, the power valve has absolutely nothing to do with the idle circuit. And that seems to be where the problem is, correct?

Not entirely certain the problem is only with the idle circuit per se. The main issue is the bluish exhaust and the fouling of the plugs - conditions I am attributing to a rich fuel condition.
As an aside, what test could be performed of the carburetor to ensure it is functioning properly? There is a scarcity of shops that do carburetor work here in my area. We seem to be a dying breed.

 

[gthumb]

Cleanliness is paramount in a carb rebuild. Did you ensure the idle air bleed holes are not clogged or blocked ?

No, I did not specifically ensure that the idle air bleed holes were not clogged or blocked. I will try to do that. What is the best way to do so? Spray carb cleaner through them, or run a thin wire through the channel. Holley does not recommend the wire route, as they say it could damage the interior of the passage

 

[WileE]

No, I did not specifically ensure that the idle air bleed holes were not clogged or blocked. I will try to do that. What is the best way to do so? Spray carb cleaner through them, or run a thin wire through the channel. Holley does not recommend the wire route, as they say it could damage the interior of the passage

Spray, don't wire it.

 

[gthumb]

Spray, don't wire it.

OK, will do.

 

[beanhead]

A leaking PV has no effect on idle. The idle screw test in post #31 does not prove anything related to the PV.

The PV is part of the main cct. Enough air speed [ increase in engine rpm ] has to pass through the throttle bores to activate the main system [ main jets ]. If the PV was blown, then the carb would be very rich at this higher rpm, but not at idle.

You're CLUELESS as to how a Holley functions if you think a blown/leaky PV won't affect idle....

 

[gthumb]

Spray, don't wire it.

Do you have to remove the small set screws in the air bleed holes? There are 4 on either side of the carb, and the outside ones appear to have set screws with larger internal passages, whereas the inner ones have set screws with very small passages. Carb cleaner goes freely through the air bleed holes with the bigger passages.
Should I remove those set screws, and how are they removed? Greatly appreciated.

 

[beanhead]

Do you have to remove the small set screws in the air bleed holes? There are 4 on either side of the carb, and the outside ones appear to have set screws with larger internal passages, whereas the inner ones have set screws with very small passages. Carb cleaner goes freely through the air bleed holes with the bigger passages.
Should I remove those set screws, and how are they removed? Greatly appreciated.

Yes, if you're spraying cleaner through the passages, remove the bleeds. Those you can put a wire through to make sure they're clear.
Wear your eye protection!

 

[gthumb]

Yes, if you're spraying cleaner through the passages, remove the bleeds. Those you can put a wire through to make sure they're clear.
Wear your eye protection!

what do you use to remove the bleeds?

 

[beanhead]

what do you use to remove the bleeds?

An allen wrench...
Maybe I assumed too much from other posts that you had removable bleeds. If they don't have a hex top , then they aren't removable and you will have to spray though them. Not a big problem; but the best way then is to spray from the body side (metering blocks removed).

 

[beanhead]

Wear your eye protection!

 

[WileE]

Theres two holes inside each venturi. The idle air bleed hole is on the outside.

 

[beanhead]

@gthumb here is a good general reference for what hole goes where
(sorry, it's kinda blurry I know..)

 

[WileE]

Wear your eye protection!

 

[RemCharger]

For a little background, the carb is a Holley 750 cfm with mechanical secondary

No. If that's yours in the picture, it's a vacuum secondary.

3) Fuel bowl levels have been adjusted so that the fuel level is just below the opening of the sight screw on the side of the bowl

. I have adjusted the needle seats to the point where the fuel level is just below the opening in the fuel bowl when I remove the sight plugs. I check this after shutting the vehicle off. Should I do it while it is running?

Yes to do it properly it should be running.
You should be quick while doing it, and a bit may dribble out while doing it.

As for the gaskets, they came from a kit provided by Holley, not an aftermarket no-name set of gaskets. However, how would incorrect gaskets create this situation?

I wonder if you had the correct stack of gaskets for the secondary metering plate. For a vacuum secondary 3310 by the looks of it

 

[AR67GTX]

I recently had a Holley doing this on my Vette. Note the hole down in the base plate known as the spark port. Fuel was running out of them and the transition slot and soaking the bottom of the base plate. Everything above the bottom of the base plate was staying dry.



This was on my bench. I filled the bowls up through the vent to the bottom of the bowl view port so fuel pressure, needle and seat and float setting had nothing to do with it. I took the bowl and meter block off and vacuum checked the PV which was new. It was fine. I removed the PV and discovered I had installed 2 gaskets on it, they were apparently stuck together. I then checked the metering block for flatness (it was flat) and verified the gasket to the main body that I had installed a few weeks before was identical to the one that had been on it for a couple of decades (it was). I applied a thin coat of transmission assembly lube to both sides of the same gasket and reinstalled everything, refilled the bowl to the bottom of the side view port and let it sit over night. Didn’t leak a drop and the car started OK when I reinstalled it. All I can figure is the extra gasket on the PV created a leak or the metering block gasket was somehow not sealing although the screws were well tightened.

Holleys can be a weird duck. Sometimes you just have to pull them apart and put them back together again to get them to work.

 

[Geoff 2]

Beanhead,
Your post #46. With your superior knowledge, explain how a leaking/blown PV affects idle. How does the leaking fuel get into the engine?????????

 

[RemCharger]

through the vacuum port that blew out the pv in the first place.

 

[Geoff 2]

I apologise to Beanhead. He is correct, leaking PV will affect idle.

 

[gthumb]

No. If that's yours in the picture, it's a vacuum secondary.



Yes to do it properly it should be running.
You should be quick while doing it, and a bit may dribble out while doing it.

I wonder if you had the correct stack of gaskets for the secondary metering plate. For a vacuum secondary 3310 by the looks of it

Yes, you are correct. It is a vacuum secondary. I am somewhat of a novice, and used the wrong terminology. Which gasket exactly are you describing? The one between the metering block and the main body of the carb?