Carburetor Help
FTE Legend
Joined: Nov 2015
Posts: 30,935
Likes: 4,124
From: Angier, NC
yes sir I know the fuel won’t go down without the secondaries opening. The issue is that while the engine is running, the fuel comes out of the rear vent tube and completely floods out the engine. No amount of adjustment, hitting it with a hammer, or anything else I’ve tried has done anything to help this issue
I am saying lower the level and then just turn the adjustment a little, if it then pushes fuel out the vent i would swap the 2 needles and seats and see if the front now dose the same thing.
If it follows replace the needle as you can get just the needle & seat.
Dave ----
Hotshot
Joined: Feb 2004
Posts: 10,839
Likes: 2,612
From: The Shenandoah Valley
Holley has it in their technical library on line, but yes, those floats are adjusted by moving the inlet needle / seat up or down. The screw is tightened to lock it, turn it to release the nut. Turning the nut while holding the screw steady will adjust the float up or down, while engine is running using the sight screw on far side. (1) 2005 H/W fuel layout
FTE Legend
Joined: Nov 2015
Posts: 30,935
Likes: 4,124
From: Angier, NC
Holley has it in their technical library on line, but yes, those floats are adjusted by moving the inlet needle / seat up or down. The screw is tightened to lock it, turn it to release the nut. Turning the nut while holding the screw steady will adjust the float up or down, while engine is running using the sight screw on far side. (1) 2005 H/W fuel layout
Lower the level in that bowl and adjust it up a little bit at a time and I bet it will work as it should as I have not known a needle / seat to go bad, just floats.
Dave ----
Thread Starter
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Cross-Country
Joined: Oct 2020
Posts: 52
Likes: 9
From: UT
I understand how to adjust the float level. The issue I’m having is that the needle and seat are adjusted all the way down to stop fuel flow. If I adjust the needle and seat up at all, the bowl will overfill until fuel comes out of the vent tube. That’s why I’ve been trying to figure this out as I’ve been essentially driving my truck with a 2 barrel carb and would like to have my secondaries be useable.
FTE Legend
Joined: Nov 2015
Posts: 30,935
Likes: 4,124
From: Angier, NC
I understand how to adjust the float level. The issue I’m having is that the needle and seat are adjusted all the way down to stop fuel flow. If I adjust the needle and seat up at all, the bowl will overfill until fuel comes out of the vent tube. That’s why I’ve been trying to figure this out as I’ve been essentially driving my truck with a 2 barrel carb and would like to have my secondaries be useable.
As a test you could swap the front & rear needles and see if the flooding follows.
I just never had one do like yours unless the fuel PSI was way too high and yours in not if the front dose not over flow.
The bowls are common filled thru the transfer tube between them and being fuel comes in the front bowl first so they both get the same PSI.
As said you can replace the needles with out removing the bowls or carb, they unscrew out of the bowl.
Dave ----
5th Wheeling
Joined: Apr 2023
Posts: 42
Likes: 17
It sounds like a float problem. If your float has a leak in it or is stuck at the bottom of its travel it won't shut the needle and seat off unless they are completely closed. I would pop the bowl off, carefully, and check the float.
Lead Driver
Joined: Oct 2018
Posts: 7,894
Likes: 2,372
It's a very simple system and the fix will be simple as well .
pop the rear bowl off, it should have the blue gaskets if it's a newer carb and they're reusable for multiple times. lift the float up until the needle valve is firmly against the seat, the float should be about level. you can blow on a piece of vacuum hose jammed in the feed to test its function. most likely you have some wrong parts, or the float tab is bent way out of context.
The only other possibility is you have the wrong metering block gasket or something like that.
pop the rear bowl off, it should have the blue gaskets if it's a newer carb and they're reusable for multiple times. lift the float up until the needle valve is firmly against the seat, the float should be about level. you can blow on a piece of vacuum hose jammed in the feed to test its function. most likely you have some wrong parts, or the float tab is bent way out of context.
The only other possibility is you have the wrong metering block gasket or something like that.
Hotshot
Joined: Feb 2004
Posts: 10,839
Likes: 2,612
From: The Shenandoah Valley
Was passing a tanker truck on US-411 near Chatsworth, Ga. .... got it done too.
Sounds like a bad needle or some trash trapped between the needle and seat, maybe in your cranking the adjustment down bent the float arm or the little tang that rides on the end of the needle. Might be a saturated heavy float if black, or flooded brass float full of fuel.
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Thread Starter
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Cross-Country
Joined: Oct 2020
Posts: 52
Likes: 9
From: UT
I bought it brand new from Holley! I guess they didn’t tighten the screws down or something because all of them were loose!
Hotshot
Joined: Feb 2004
Posts: 10,839
Likes: 2,612
From: The Shenandoah Valley
- A) how fare out it is backed in relation to the float bowl mounting surface (blue gasket area)
- B) how far is the float recessed into the float bowl from the same float bowl mounting surface
- C) compare the two.
Those screws, been dealing with them since near 1970, "clutch head screws" they are called, I have an old screw driver ground to fit them. They were actually intended to make for faster assembly on a line, and I've never seen a Holley jet or metering plate without them in use. My 1850 is either a 1960 or a 1970 carb, it has them.
I'd check all the fasteners I could get to without total disassembly, tighten up those screws, make sure my float moved freely, and put it together after setting a dry float level, then readjust for wet float while running. Good chance, if it come like that, the float inlet needle / seat has never had to do anything.
Thread Starter
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Cross-Country
Joined: Oct 2020
Posts: 52
Likes: 9
From: UT
I can see it catching the float when it was low and not letting go keeping it low as the fuel level rose around it. I'd measure
Those screws, been dealing with them since near 1970, "clutch head screws" they are called, I have an old screw driver ground to fit them. They were actually intended to make for faster assembly on a line, and I've never seen a Holley jet or metering plate without them in use. My 1850 is either a 1960 or a 1970 carb, it has them.
I'd check all the fasteners I could get to without total disassembly, tighten up those screws, make sure my float moved freely, and put it together after setting a dry float level, then readjust for wet float while running. Good chance, if it come like that, the float inlet needle / seat has never had to do anything.
- A) how fare out it is backed in relation to the float bowl mounting surface (blue gasket area)
- B) how far is the float recessed into the float bowl from the same float bowl mounting surface
- C) compare the two.
Those screws, been dealing with them since near 1970, "clutch head screws" they are called, I have an old screw driver ground to fit them. They were actually intended to make for faster assembly on a line, and I've never seen a Holley jet or metering plate without them in use. My 1850 is either a 1960 or a 1970 carb, it has them.
I'd check all the fasteners I could get to without total disassembly, tighten up those screws, make sure my float moved freely, and put it together after setting a dry float level, then readjust for wet float while running. Good chance, if it come like that, the float inlet needle / seat has never had to do anything.
Hotshot
Joined: Feb 2004
Posts: 10,839
Likes: 2,612
From: The Shenandoah Valley
I did end up stripping the carb down before I went to work today. That screw was maybe threaded in one or two threads. It was sticking out about 1/4 inch. ... etc ... I guess if anyone else buys a new carb from Holley, you need to strip it down and tighten all the fasteners you can see!
I agree, it just didn't occur to me earlier as I've never seen them loose. I've checked screws on carburetors, but usually I was rebuiling one, and those screws usually will stay tight. Every model 4160 with secondary metering plates uses 6 of those screws. They are a #8-32 thread, and the teeth on the underside of the sunken head bites into the plate and effectively keeps them tight once they are tightened. If you open one up and the screws are different, look out 'cause you ain't the first in there.
One can look around and find regular Philips head #8-32 screws with countersunk heads, maybe even find some with the teeth that keep them tight, & can even use them if length is right.