Whistling Motor, Vacuum leak

[Tias63]

Yes, I'm sure it's a Vacuum leak, but having a hek of a time finding it. I've done the spraying of a water bottle (with water) and nothing as far as changes in the idle. You only seem to hear this whistling when the motor is nice and hot, thus I don't feel comfortable spraying with Brake Cleaner, Carb Cleaner...
Any other tips or ideas?
The only time I've noticed a change is when I disconnect the vacuum advance, and the whistling will stop, but if I rev up the motor it will start again. Weird

 

[hunt2elk]

I have used a propane torch, unlit of course. Not messy and doesn't ruin paint.

 

[Tias63]

I have used a propane torch, unlit of course. Not messy and doesn't ruin paint.

Yeah, I saw that method on YouTube.
Thanks man

 

[RemCharger]

What motor /carb?

 

[khryslerkid]

Try turning the carb air and fuel mixture just a little.

 

[Ghostrider 67]

Check the vac advance case body for cracks...also the under hood heat tends to make the stretched ends of vac lines harden and a vac slips around them. Snip off the first inch or so and reattach.

 

[Ranger16]

Try a mechanics stethoscope. A vacuum leak will sound like a hurricane.

 

[Lefty71]

I would try troubleshooting the vacuum advance with a brake bleeding vacuum pump.... see if it holds...maybe the noise is coming from the distributor..

 

[RemCharger]

Yes a piece of heater hose will work good.

Try a mechanics stethoscope. A vacuum leak will sound like a hurricane.

 

[steve340]

Have a listen at the carburettor throttle shaft.

 

[1967coronet]

This will sound nuts but I had a replacement pcv valve that would whistle at idle.
It was a plastic napa replacement one.

I swapped in a oem used one and the whistle was gone.

 

[RemCharger]

318 poly

What motor /carb?

 

[AR67GTX]

Have you changed the carb base gasket lately? I once tried a single opening gasket under an Edelbtock carb on my 67 GTX and it whistled loudly until I put ac4-hole gasket under it.

 

[Tias63]

What motor /carb?

383 with a Holley 3310 I believe, Vacuum Secondary

 

[RemCharger]

383 with a Holley 3310 I believe, Vacuum Secondary

OK. Do all of the above checks.. but holleys can often make a whistle as the air goes by the throttle blades.
Like Khryslerkid said, try giving the fuel mixture screws some love.

 

[dadsbee]

My Holley whistled just as I gave it a bit of gas.. before I rebuilt it..

 

[Shorthorse]

Does your car idle OK? I would think that with a vacuum leak you can hear, your car would not idle at all.

 

[khryslerkid]

All good suggestions

This will sound nuts but I had a replacement pcv valve that would whistle at idle.
It was a plastic napa replacement one.

I swapped in a oem used one and the whistle was gone.

A former brother in law had a Ferd truck and he said it had a whistle. No one could hear it but him. Well when he changed the PCV valve he said it was gone. Glad it did the trick

 

[Tias63]

Does your car idle OK? I would think that with a vacuum leak you can hear, your car would not idle at all.

Idles and runs just fine. I found that if I disconnect the Vacuum advance, the whistling stops until I rev the motor. Then the whistle will return then stop when the motor idles down. The Carb was rebuilt about 2 years ago, but I'm going to clean it up and try a new gasket.

 

[Ron H]

Great suggestions here, have a poly with factory intake with a tad larger carb on it and there’s not a ton of ‘sealing’ room around the base, has to be set square as possible. Check the base for vac leaks as posted and bolts torqued evenly.