WHISTLING FROM CARB??

[Anonymous]

I have a whistling coming from my carb when Step on the gas, it doesnt whistle all the time only when accelerating. Under normal cruising it whistles when taking off from a light or a stop sign but once up to speed its fine. What could cause this? I have a rebuilt motorcraft 1101. could it be tuned wrong? How do you adjust the rich lean screw? Too rich or lean?

 

[Mustangaroo]

Steve it sounds like you have a vacumn leak, check the carb over and also all vacumn lines.

 

[JackFish]

Try tightening any bolts or nuts you have access to. Might just be leaky and loose.

 

[Anonymous]

Every thing is tight and I sprayed around the carb, no leaks, the engine runs smooth. Could it be the mixture screw? I adjusted it half fast as I dont know how to adjust it properly. There ar only two vacum lines and they go to the distributer and pcv valve.

 

[simon]

what air cleaner assembly are you running?

those sporty open element air cleaners tend to create a hissing noise at WOT, the smaller, the more intense.

usually, noise is not a factor when fine tuning carburetors.
Among others, RPM, spark plug color, and CO and NOX percentage in your exhaust fumes are factors when tuning a carburetor. But noise... not really. timing initial advance, yep, thats something some guys do by ear, but carbs? at least not on noise alone-.

Keep us posted on what you´ll find out

 

[Anonymous]

what air cleaner assembly are you running?

those sporty open element air cleaners tend to create a hissing noise at WOT, the smaller, the more intense.

usually, noise is not a factor when fine tuning carburetors.
Among others, RPM, spark plug color, and CO and NOX percentage in your exhaust fumes are factors when tuning a carburetor. But noise... not really. timing initial advance, yep, thats something some guys do by ear, but carbs? at least not on noise alone-.

Keep us posted on what you´ll find out

The air cleaner is a 5" open element air cleaner, Are you saying this is the cause? My throttle response is instantainious so I dont see the sound as affecting performance, It is just anoying when you are cruising.

 

[wallaka]

Yep that's probably it.

 

[MustangSix]

The original air cleaner is also a muffler. The single bbl carb makes an awful sucking sound at some speeds.

 

[strat1960s]

My Weber 38 did the exact same thing as you are describing. It would whistle after I was driving for a while and shut the car off. When I started the motor up it would whistle until it warmed up. I was told it was in the butterfly and that there wasn't really much to do to fixe it. After it warmed up it went away.

 

[Anonymous]

Heres a stupid question, should the choke tube have vacum? I do not have a choke tube connected to the carb and the hole on the carb is wide open should I plug it?

 

[tetraethyllead]

I have a whistling coming from my carb when Step on the gas, it doesnt whistle all the time only when accelerating. Under normal cruising it whistles when taking off from a light or a stop sign but once up to speed its fine. What could cause this? I have a rebuilt motorcraft 1101. could it be tuned wrong? How do you adjust the rich lean screw? Too rich or lean?

Check the bolts/nuts that are holding the carb to the intake.

I had whistling noise on my mav... first it seemed to be coming from the alternator, so I replaced the bearings in the alternator (they had been squeaking before and needed it anyway) but the sound remained. Turned out the carb was siting loosely on the gasket. I tightened it down and everything was fine again.

What was remarkable was I detected no performance problems from it being like that what so ever.

 

[lightnin-boy]

I have a Holley 1946 that whistles at idle... There are no vacuum leaks and the car runs fine. I've just come to accept it.

Kirk

 

[CobraSix]

Just tell everyone it's your new turbo...problem solved!

Slade

 

[Anonymous]

take off the air cleaner and see if that changes the tone of the whistle. Likely it's just the air cleaner assem. Carbs do create a lot more noise than expected. Get someone else at the pedal and your ear at the noise.
Tuneing a 1bbl mix screw is real simple --slowly turn it in till it starts to stumble then slowly turn it out till it starts to stumble -the turn it back to the center of these two spots. Of course do this fully warmed up and choke open fully at a slow idle. then turn your idle back up a little. Do this 3 or 4 times and you'll get the feel for it. you won't even have to turn as far as the stumble to tell the diff. You're just looking for the fastest smoothest idle. These carbs are real low tech and remember this only affects the mix at low rpm and zero to slight throttle. One of the earliest carbs was the bottom of a soup can with gas dripping onto it with it positioned at the intake port. The vacumn sucks in the fumes. Faster drip more rpm. Yours is a little more evolved but the theory is still pretty basic.

 

[CZLN6]

Howdy Steve and All:

Yes Steve, the choke has a vacuum pull-off source through the heat stove from the exhaust manifold. IF not in use, it should be plugged. Plugging it will help keep the inside of your carb cleaner too. How will you actuate your choke?

To tune your low speed idle screw, turn it in until it just touches stop. Do not snug. Now turn it out 1 1/2 turns. Now start up and warm up the engine so that it idles normally. Set the idle as slow as possible. Now slowly turn the air screw in until the engine loses rpm, then back the screw out 1/2 turn. This is a good starting point. Now slowly turn the screw in, then out, listening for an increase in rpm. Find the setting position that gives you the highest rpm. This will likely be the highest vacuum reading too.

Setting the low speed idle screw in this way is ok, but it is really best for an inexperienced tuner to set the initial advance with a timing light.

What distributor are you using with the 1101?

Adios, David

 

[Anonymous]

... The single bbl carb makes an awful sucking sound at some speeds.

Tell me about it, lol