Summit (Holley 4011) carb draining

[65_Satellite]

Hey guys. After converting my 65 Satty to a 4spd I wanted to go with a 750 double pumper and swap out the 750 vac secondary that I had. I ended up getting this summit racing 750. Was told it was a rebranded Holley 4011 from back in the day. Well after swapping out power valves and jetting to my cars needs, I got her running like a champ but overnight the primary float drains out and I have to prime it to start the car. When it fires up (cause it acts like it’s flooded) it blows massive black smoke out the exhaust. The idle mixture screws don’t make a diff and I can even turn them in all the way and the car still runs. Thought maybe it was a bad PV so put another new one in with same results. Now I know for a fact that my transfer slot is showing a little more than square because i have to turn the idle set screw up a little to get the car to idle. Could the transfer slots cause the fuel bowl to drain? Not sure what to check from here. Always had Eddys on my cars but from recommendations I wanted to run a Holley.

 

[493 Mike]

I have never seen one of these carbs before but, I believe the trouble could still be in the power valve or its circuitry. Could even be a casting flaw (I assume it is a Chinese product).
Mike

 

[66chargerpat]

Fill the bowls with gas and see were it leaking from.
Put something under the outer edges to hold it up high enough to see the bottom.

 

[65_Satellite]

Fill the bowls with gas and see were it leaking from.
Put something under the outer edges to hold it up high enough to see the bottom.

So if I fill the bowls and let it sit overnight on the bench, it DOESNT leak but if I put it on the car and run it and then let it sit, it empties the primary bowl and when I go to start the car it’s flooded and when it fires up, it’s so rich it’s pouring black smoke out the exhaust til it clears up

 

[66chargerpat]

I wonder if heat is opening something up?

 

[RemCharger]

Maybe residual fuel pressure blowing past the needle and seats

 

[65_Satellite]

Maybe residual fuel pressure blowing past the needle and seats

Is there a way to check that?

 

[RemCharger]

Is there a way to check that?

One way is to put new ones in. They go shitty fast with the new shitty gas.

 

[65_Satellite]

One way is to put new ones in. They go shitty fast with the new shitty gas.

Ok it’s a brand new carb with presumably brand new needle and seat but I have an unopened Holley trick kit with new ones in that so I will at least give that a try and see what happens but here's what's weird. I started the car, checked the float bowl and it was halfway full. Ran car for 2 minutes, snapping throttle a couple times. Car never made it to operating temp. Let it sit for 3 hours and the primary bowl drained out and went to start it and engine was flooded. When it fired, it blew tons of smoke and smelled horribly rich......took carb off last night, set it on bench and filled the floats. Checked this morning and not a drop of fuel came out and both bowls still full. Why is it that it's draining out when on the car but not on the bench? And it's not evaporating cause it doesn't even get hot enough

 

[65_Satellite]

I have never seen one of these carbs before but, I believe the trouble could still be in the power valve or its circuitry. Could even be a casting flaw (I assume it is a Chinese product).
Mike

Its the old Holley 4011 design. They stopped using it and turned over the design to summit. its all Holley parts and tuning kits. Ive changed the PV twice and its the same thing. What's strange is it will drain the primary completely empty in about 3 hours after parking the car but it I take the carb off and let it sit on the bench overnight with the fuel bowl full, it won't leak a drop..

 

[65_Satellite]

Fill the bowls with gas and see were it leaking from.
Put something under the outer edges to hold it up high enough to see the bottom.

Thats the thing is there is no visible signs externally but the car acts as if its flooded when I start it and it smokes really bad. Not to mention, the oil now smells of fuel and needs to be changed. If I take the carb off and let it sit on the bench overnight, it won't leak a drop and the level in the glass sight is exactly the same. If I put it on the car and run it for even 5 minutes and let it sit, the level drops. I can see the fuel halfway through the sight glass and within 3 hours you cant see any fuel (primary only - secondary doesn't budge). If I then remove the top of the carb and look into the bowl, its bone dry

 

[493 Mike]

Send it back to Summit?
Mike

 

[66chargerpat]

Maybe try adding some ATF in the bowl vent when you stop the engine.
The dye may help you find it. The casting may be porous.
Just a guess.

 

[furious70]

When you run it and then shut it off, with the air cleaner off observe from the top for awhile, do you see gas trickling out of the venturis?
This could help tell if you've got pressure in the bowls that's escaping, a plugged vent, etc vs a cracked casting

 

[65_Satellite]

Send it back to Summit?
Mike

Called them and before they take it back they need me to troubleshoot it with a tech guy

 

[493 Mike]

Called them and before they take it back they need me to troubleshoot it with a tech guy

Progress!
Mike

 

[samr820]

Progress!
Mike

Any insight what the issue was? I am having the same issue on a 454 boat engine with a 4011 spread-bore carburetor.