I think this is the 2nd time you posted this.
I was waiting to see what others would say.

Can't exactly follow about the 'bell' part..
but normally Iwould not expectadding an air box to increase idle rpm.

Did you just try to adjust it down some ?

scott
www.turbovans.com

On 12/22/2012 6:50 PM, David Moyal wrote:
> Question to you dieseleros: Putting (I hope) the finishing touches to my
> '83 1.6NA - to - 1.9 AAZ TD. I picked up a '92 Dodge Caravan airbox at the
> wreckers. Diameter of inlets (2.5") matches inlet to the turbo, but is
> smaller than the "bell" on the airbox connector tube that came with my
> motor. I noticed that after hooking up the airbox my warm idle has gone up
> significantly. Can reducing the end diameter of the inlet tract increase
> idle speed? Any other comments appreciated.
> Side comment re: mufflers: my local muffler guy did a nice clean job
> putting in a thru-flow muffler. Because he couldn't get one 25" long (like
> the original) he had to fabricate the right hand bracket to jog over to the
> stock mount. The bends from the header to the muffler were tough - he spent
> 5 hours on it. So not cheap! But a nice clean install. BTW, I had him but
> an O2 sensor boss on the pipe as close to the header as I could. I can put
> an exhaust temp monitor on there if I want.
> Thanks for comments, David
> '61 R 69S
> '83 Westy
>