The Ford Barn

Steve Plucker · 04-05-2020, 08:32 PM

What cause a Zenith or Holley Model A Ford carburetor, when at an idle, to sound like someone trying to suck up all the liquid at the bottom of an almost empty glass of soda with a straw?

Thanks.

Pluck

daren007 · 04-05-2020, 08:39 PM

That’s pretty much what is happening.

Gary WA · 04-05-2020, 08:40 PM

One of mine does that on the Delivery! Air adjustment screw? Haven't really messed with it yet! Might play around with it this next week.

Conaway2 · 04-05-2020, 09:31 PM

That’s what my 31 roadster sounds like at idle....

Benson · 04-05-2020, 11:18 PM

apparently post does not apply

redmodelt · 04-05-2020, 11:51 PM

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Even my 48 6 makes that sound at idle. The Older updraft Strombergs instructions state that you should hear the fuel gurgleing at idle, I think the Zenith's are the same. Means it's set about right.

daren007 · 04-06-2020, 06:27 AM

At idle the throttle plate is closed..well almost causing Air to be drawn through this small opening. This is where fuel for idle is picked up. You are hearing the fuel mixing with air at idle.

Jack Shaft · 04-06-2020, 08:32 AM

Stock model a ford engine is starved for fuel, the carb runs about half the airflow of the engines capacity..thus the air speeds through the venturi at a high rate. Flathead V8's set up stock are really neat,all you hear is the air rushing into the carburetor.

P.S. · 04-06-2020, 08:54 AM

If the air bleed screw is adjusted in all the way, then it will sound like that. However, that also almost certainly means an intake leak if that's the setting it runs best.

rocket1 · 04-06-2020, 10:56 AM

The zenith carb on my 29 sounds the same at idle.

30 Closed Cab PU · 04-06-2020, 12:06 PM

I do not think the noise is unusual on carbureted cars. I remember hearing the same noise back in the early 70s when I had my 1st cars. Normally would not hear it until you took the air filter out, seemed loudest at idle. An air rushing/accelerated past something restricting it. Possibly the air being restricted and running through the venturi?

daren007 · 04-06-2020, 12:09 PM

Throttle plate.

30 Closed Cab PU · 04-06-2020, 12:15 PM

Quote:

Originally Posted by daren007

Throttle plate.

Brain Fart - you are so right.

daren007 · 04-06-2020, 09:20 PM

Not to worry, I have plenty of those myself.

Wick · 04-07-2020, 04:00 AM

What I have found,all my good carbs I run on my truck make this noise. But I also run a H.C head. Engine is tight,no air leaks.
I don't hear it on a bone stock engine with Lot's of miles.

04-05-2020, 08:32 PM	#1
Steve Plucker BANNED Join Date: May 2010 Location: Walla Walla, Washington USA Posts: 6,066	Carburetor noise... What cause a Zenith or Holley Model A Ford carburetor, when at an idle, to sound like someone trying to suck up all the liquid at the bottom of an almost empty glass of soda with a straw? Thanks. Pluck

04-05-2020, 08:39 PM	#2
daren007 Senior Member Join Date: Apr 2015 Location: Saint Cloud Mn Posts: 745	Re: Carburetor noise... That’s pretty much what is happening.

04-05-2020, 08:40 PM	#3
Gary WA Senior Member Join Date: May 2010 Location: Clinton,WA/Whidbey Island Posts: 4,104	Re: Carburetor noise... One of mine does that on the Delivery! Air adjustment screw? Haven't really messed with it yet! Might play around with it this next week. __________________ www.whidbeymodelaclub.com

04-05-2020, 09:31 PM	#4
Conaway2 Senior Member Join Date: Apr 2019 Location: Mt. Pleasant, SC Posts: 601	Re: Carburetor noise... That’s what my 31 roadster sounds like at idle....

04-05-2020, 11:18 PM	#5
Benson Senior Member Join Date: May 2010 Posts: 2,595	Re: Carburetor noise... apparently post does not apply Last edited by Benson; 04-06-2020 at 07:51 AM.

04-05-2020, 11:51 PM	#6
redmodelt Senior Member Join Date: May 2010 Location: Portland OR Posts: 6,340	Re: Carburetor noise... Sponsored Links (Register now to hide all advertisements) Even my 48 6 makes that sound at idle. The Older updraft Strombergs instructions state that you should hear the fuel gurgleing at idle, I think the Zenith's are the same. Means it's set about right. __________________ I know the voices aren't real but damn they have some good ideas!

04-06-2020, 06:27 AM	#7
daren007 Senior Member Join Date: Apr 2015 Location: Saint Cloud Mn Posts: 745	Re: Carburetor noise... At idle the throttle plate is closed..well almost causing Air to be drawn through this small opening. This is where fuel for idle is picked up. You are hearing the fuel mixing with air at idle.

04-06-2020, 08:32 AM	#8
Jack Shaft BANNED Join Date: Dec 2019 Posts: 1,196	Re: Carburetor noise... Stock model a ford engine is starved for fuel, the carb runs about half the airflow of the engines capacity..thus the air speeds through the venturi at a high rate. Flathead V8's set up stock are really neat,all you hear is the air rushing into the carburetor.

04-06-2020, 08:54 AM	#9
P.S. Senior Member Join Date: Jul 2012 Location: California Posts: 1,695	Re: Carburetor noise... If the air bleed screw is adjusted in all the way, then it will sound like that. However, that also almost certainly means an intake leak if that's the setting it runs best.

04-06-2020, 10:56 AM	#10
rocket1 Senior Member Join Date: Mar 2014 Location: Midland Park,N.J. Posts: 1,108	Re: Carburetor noise... The zenith carb on my 29 sounds the same at idle.

04-06-2020, 12:06 PM	#11
30 Closed Cab PU Senior Member Join Date: Aug 2018 Posts: 2,332	Re: Carburetor noise... I do not think the noise is unusual on carbureted cars. I remember hearing the same noise back in the early 70s when I had my 1st cars. Normally would not hear it until you took the air filter out, seemed loudest at idle. An air rushing/accelerated past something restricting it. Possibly the air being restricted and running through the venturi?

04-06-2020, 12:09 PM	#12
daren007 Senior Member Join Date: Apr 2015 Location: Saint Cloud Mn Posts: 745	Re: Carburetor noise... Throttle plate.

04-06-2020, 09:20 PM	#14
daren007 Senior Member Join Date: Apr 2015 Location: Saint Cloud Mn Posts: 745	Re: Carburetor noise... Not to worry, I have plenty of those myself.

04-07-2020, 04:00 AM	#15
Wick Senior Member Join Date: May 2010 Location: Gwynn's Island Va Posts: 1,386	Re: Carburetor noise... What I have found,all my good carbs I run on my truck make this noise. But I also run a H.C head. Engine is tight,no air leaks. I don't hear it on a bone stock engine with Lot's of miles.