running 5.0 style TB on my 383 mopar with an alum 90* elbow. Upgraded from stock 5.0 to a used 70mm BBK TB. I've got a whistle that has got to be a vacuum leak but I cannot find it. I've tried new gaskets ( 1 and stacked), have sprayed carb cleaner all over the joints of TB/elbow/intake with no effect. I'm down to wondering about the shaft seals in the TB or something, but it feels nice and tight. I didn't have the whistle before the swap. It'll change pitch with different throttle angle driving, and is loud when I shut the engine off. With the TPS on one end is there any way to test the shaft seals? Any other ideas? The stock IAC port is capped and spraying cab cleaner on that joint doesn't make a difference either. The big port on the side of the TB inlet is plugged and I RTV'ed the joint where it presses into the housing just in case.

 

its not a leak, trust me, its the notorious BBK TB whistle, sometimes you can get rid of it by rotating the vac port that comes out the top by 90 or 180 degrees, if that doesnt work you have to get a dremel and clean the burs where that vac port enters TB.

 

So that port is known for burrs and vac leaks or is it an acoustic design problem with the port the makes it whistle?

 

Yup they always do that; I drilled an 1/8" hole in the throttle plate, problem solved..... Never played with that vacuum port at all though. Makes sense, the hole I drilled may have just been a band-aid for another problem. Just another opinion.....

 

Dang, wish I would have researched that b4 buying it, it's quite annoying.

 

just use a dremel to clean the trasition from the port to TB, once its smooth and not sharp it'll stop whistleing

 

Understood now, thanks

 

Drudging this back up because I did bevel the entry to that vac port and the OEM IAC port and it really didn't make much difference, if any. Do I have to get really aggressive with the porting into the entries? I figured if I just took the sharp edge off it would quiet down. Has anyone resorted to plugging the holes?

 

I also have fixed it by drilling a hole in the blade and closing the idle screw more. This works at idle, but it will still give a small whistle when you crack the throttle slightly and can cause the blade to stick in the bore at times.

Best bet is to ditch it and get an Accufab.