Throttle Body whistle

[davekp]

Installed a new BBK 70mm throttle body on my '91 based 302. The whistle, almost a shriek, at idle is annoying. I did a search and apparently this is a common issue on the Mustang forums. Anyone here found a cure?
Some claim chamfering the IAC holes helps.
Thanks in advance.
Dave

[Jeff Kleiner]

Some claim chamfering the IAC holes helps.

It has when I've done it.

Jeff

[davekp]

Thanks, Jeff.

[davekp]

Tried rounding the sharp corners on the IAC holes- didn't seem to help.
Any other ideas? The 70mm throttle body is mating to a 75mm inlet on the intake manifold. Could this be an issue?

[steno]

I basically rounded the ports to match ( more or less) the factory throttle body with a dremmel. No whistle !!

[davekp]

Fixed!
I went back and did some more rounding of the IAC ports on the throttle body. Also, the hole on the BBK was smaller than the OEM so I opened it up. Whistle almost gone. Added an IAC adjuster plate I had and the whistle is now completely gone.