383 whistles ????

Hi all ... I have an all stock 69 383 that will whistle around 1/4 throttle.I have put 3 different carbs on it (2 holleys and 1 edelbrock) with 1/2 inch spacer and it will still whistle. If I back out of it or give it more it goes away... is it the intake ? whatcha think ? thanks

I had a 383 do that too, I just thought it was the carter carb.

If you have changed out your carbs, I dunno

Maybe put a 4 hole spacer on it to mix up the air flow a little and see what happens?

eight

Can you ID it maybe w a stethoscope if you can get that same amt of load (1/4 throttle) in your driveway & maight have to jack up the rear & put it in gear to load it. Might b able to hear it there w the hood opened

You can spray water around the base of the cab (spray bottle) and see if the whistle changes or goes away.
If it does you've got a vacuum leak at the carb base.

I've seen some carbs have vacuum ports exposed to the air causing a whistle and leaks

I had the same problem on my Newport. Whistled while driving with an Edelbrock and a Holley carb. Does not whistle with the Carter AVS. I can't figure it out. And it only whistles while driving.

Are you using a PCV valve?

Heres the update .....After I posted ...eightlitermopar posted try a four hole spacer ..... thought to myself how hard could it be to make one out of wood...found a slab of 3/4 inch in the garage,used the 4 hole gasket as a template .... 15 minutes and done .....The whistle is gone and no more flat spot .... thanks again ......

must have had a slight vac leak, have you took it out & noticed if it runs any different/better

There is no vac leak... when I put the carb on the motor all gaskets were new...and also tried numerous times to find a vac leak(carb cleaner,spray water,propane).. .and the carb just came off my dads Lil Red and ran fine with no whistle,not to mention the other 2 carbs that had the same whistle ..... 4 hole spacer str8ened the air flow in the intake ...I have a thermoquad Im gonna try with no spacer and see what happens ...just for giggles...

maybe it's just happy?