Whistle coming from carb area?

[shortbed70]

Ok so I changed intake gaskets on my sbc and everything went well bolted the carb on hooked everything up then fired right up. After the temp came up some it started to squeal. Hit the gas it goes away for a split second. Also seems like the carb is sucking alot more air through itself. I made sure it wasn't a belt or anything else and even tried the carb cleaner around the carb and no change. So do I need to pull the intake again or any other ideas??? Need help fast.
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[Redcap]

Vacuum leak. Did you spray the throttle shaft on the carb? Got a crack in a vacuum line or cap? What kind of carb?

[shortbed70]

Originally Posted by Redcap

Vacuum leak. Did you spray the throttle shaft on the carb? Got a crack in a vacuum line or cap? What kind of carb?

I sprayed everything.. Speed demon carb vacume secondaries.
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[cdowns]

was the mounting surface cleaned and a new gasket used on the carb and torqued in place properly?

[shortbed70]

Yes tried two different gaskets on the carb/intake thick and thin.
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[72chevyk10]

did you spray on the intake to head mounting? it can leak there too

[shortbed70]

Originally Posted by 72chevyk10

did you spray on the intake to head mounting? it can leak there too

Yup.. Front and rear of intake also...
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[geezer#99]

Where's your vacuum advance hooked to?

[Redcap]

Originally Posted by shortbed70

I sprayed everything.. Speed demon carb vacume secondaries.
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There is your problem.

[shortbed70]

Originally Posted by Redcap

There is your problem.

Funny.... Been on there for three years and no problems..
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[shortbed70]

Originally Posted by geezer#99

Where's your vacuum advance hooked to?

Manifold vacume on pass front of carb other port blocked. PVC off back of carb to valve cover and if you unplug the line no change.
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[geezer#99]

Hook it up to ported vacuum. Increase your idle a bit. My truck whistles too!
Mines hooked to manifold too but it runs so much better like that.
See if that changes it.

[Redcap]

Originally Posted by shortbed70

Funny.... Been on there for three years and no problems..
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So...you aren't having trouble with it whistling (vacuum leak) then?

[shortbed70]

Originally Posted by geezer#99

Hook it up to ported vacuum. Increase your idle a bit. My truck whistles too!
Mines hooked to manifold too but it runs so much better like that.
See if that changes it.

Tried that same result..

Originally Posted by Redcap

So...you aren't having trouble with it whistling (vacuum leak) then?

Why if everythin is hooked up the same as before then why now the whistle is what I was asking? Thought maybe your one of those demon/Holley carb bashers! Because I hate people that want to knock a product because they don't like it.. U know?
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[shortbed70]

Going to try another carb( Holley) tomarrow and if no change looks like the intake is coming back off
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[Redcap]

Originally Posted by shortbed70

Tried that same result..



Why if everythin is hooked up the same as before then why now the whistle is what I was asking? Thought maybe your one of those demon/Holley carb bashers! Because I hate people that want to knock a product because they don't like it.. U know?
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Nah, I don't bash Holleys. Some guys have the patience or talent to work with them and some don't...I just can't make them run as easily as I can an Edelbrock, so that is what I use. That said...I haven't been impressed with the quality of the Demon line and neither have a couple friends that bought them. Could be isolated incidences, but...

And I was being kind of a dick, you were right. Crappy day, over it now.

Originally Posted by shortbed70

Going to try another carb( Holley) tomarrow and if no change looks like the intake is coming back off
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That is my suggestion. Look over the mating surfaces real close, maybe even with a straight edge on the carb base and carb pad on the manifold?

[shortbed70]

Originally Posted by Redcap

Nah, I don't bash Holleys. Some guys have the patience or talent to work with them and some don't...I just can't make them run as easily as I can an Edelbrock, so that is what I use. That said...I haven't been impressed with the quality of the Demon line and neither have a couple friends that bought them. Could be isolated incidences, but...

And I was being kind of a dick, you were right. Crappy day, over it now.



That is my suggestion. Look over the mating surfaces real close, maybe even with a straight edge on the carb base and carb pad on the manifold?

No problem man... Trust me I'm having a bad weekend. Spent $150 on a intake,new gaskets and fluids and ended up having to use old intake and after I tried the carb just now it still does it! Sooooo off with the intake tomarrow night to see WTH is going on... Thanks for the help and I'll keep everyone posted..
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[crazy longhorn]

I dont "bash" anybodys carbs....have run em all, & they all tune a tick differenty. But here goes.....you do not have a vac leak, properly stated, its an AIR leak You might find it in the intake gaskets....but most likely, you will find it under the carb! If it were mine, I would warm the engine(not really hot, but not cold)......shoot a little brake clean or starting fluid around the suspected spots, you will find the air leak. If you play with starting fluid, be VERY carefull! crazyL

[prostreetC-10]

It "should" be the throttle plates. Of course this is shooting from the hip as I sit on my couch. I have had one or two carbs do this and was able to eliminiate the problem by resetting the throttle plates (which I don't recommend you do if you are not familiar with these carbs. I have also swapped out bases and had the problems go away. It usually only happens at one specific RPM right? Now that I think about it, do that carb have the idleze setup on it?

[LEEVON]

All three of the last Demon carbs I ran had the "whistle" and I chalked it up to the design of the venturies and boosters. There were no vacuum leaks on mine. That was the least of my worries, the eye-burning rich idle circuit on each of them was the nail in the coffin.

[prostreetC-10]

It can be a problem with Holleys too. When I said I have had one or two do it, I was talking about Holleys. When the blades are just cracked open, there can be the perfect distance between the wall of the throttle bore and the blade to make a slight sound. Not guaranteeing this is your problem, but I know it can happen. You can also check to see if your plates are aligned. Assuming the transfer slots are cut the same, and I wouldn't be surprised if they weren't on a BG, they "should" (butterflies) hit the transfer slots in the exact same spot on each side. Surprising how many carbs are not hitting each slot in the same place.

[shortbed70]

Sorry haven't updated but the leak was coming from the rear of the intake. Apperantly it didn't seal well so since I had to take it off again I put on my Holley street dominator intake and some new gaskets and a few days later fired it up and no whistle! So not the carb... Thank god! Didn't want that bill...
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