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Senior Charter Member
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346 Posts
Discussion Starter · #1 ·
My knowledge tells me that this is a vaccum leak of some sort. as soon as i touch the throttle the sound goes away. it is a whistle not a belt noise. any input?
 

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Premium Member
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10,474 Posts
A Cobra wasn't meant to idle, so your engine sits there, bored to tears at idle, and whistles a tune :D , waiting for you to step on the go pedal!!
 

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FFCobra Fanatic
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636 Posts
A whisle is most likely a vacume leak. The best trick I know of to find it is to spray carb cleaner around the base of the carb and the intake manifold gaskets.[the most common places for vacume leaks]
If the idle goes up when spraying the carb cleaner in an area there is your leak.
MadDog
 

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Senior Charter Member
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346 Posts
Discussion Starter · #5 ·
sorry, forgot to mention, its EFI. gt40 intake with a 70mm tbody. thanks for your help
 

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Discussion Starter · #6 ·
I think so, i just bought the car today.
 

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Discussion Starter · #7 ·
I think so, i just bought the car today. the guy said that it was 'normal" for it to whistle with a 70mm, i don't buy that.
 

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FFCobra Fanatic
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636 Posts
I guess I was asuming it was a carbed car. That just makes a lot more places it could be leaking. But I like Dougs answer. If I let mine idle too long it gets angery.
MadDog
 

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Premium Member
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10,650 Posts
BBK throttle bodies do have a tendency to whistle.
 

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you can do a fix with these bbk's...do a search , I know someone posted how to get rid of the whistlin'... I think its just a matter of filing off alittle of the butterfly edges...
 

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Registered
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177 Posts
I have a new BBK and it whistles, especially at WOT. Kind of like a blower but withour the belt or boost.
 

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Willie said it best. I have put the bbk's on 2 of mine and they both whistled, but more at wot than idle.
 

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section 8
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5,136 Posts
The K+N filters whistle
I have 3 all whistle until you get them dirty a few times or you have a vacuum leak. Bob
 

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1,300 Posts
May be whistling because it doesn't know the words.... :D Sorry...couldn't resist.
 

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FFCobra Craftsman
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903 Posts
find someone that has a smoke machine. You will find it real quickly
 

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3,110 Posts
My BBK 70 mm whistles at idle, too. It is apparently a common problem. The cause is purported to be the idle air bypass ports in the throttle body. They have an unfinished, sharp edge where the port intersects with the throttle bore. The fix, which I haven't done yet, is to remove the throttle body and smooth, or round-off, those edges in the throat of the throttle body with a fine file or fine sandpaper.

Steve
http://home.thegrid.net/~ffr4776
 

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Senior Member
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8,356 Posts
Is at least one valve cover vented; ie open to atmosphere with a breather (without a PCV valve) or hooked to the elbow on the throttle body (again without a PCV valve)? My breather valve had a PCV valve in it and engine whistled as you describe, at idle, and for a few seconds when I shut the engine down. Replaced the breather with one that had no valve and whistling stopped; two much vacuum build, I think.
 
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