Re:exaust chirping

[Rob Marks <RobMar@domain.elided>]

Steve wrote:
I need to stop the exhaust chirping, it may be masking some pinging. 
Anyone remember the Navistar part number for the proper plugs for the
air
injection holes.

end snip>

The emission tube plugs #484815C1 from IH dealers.
overall length is 1" nominal.
Has .400(length) of  1/2" by -20 threads.  Head is slotted for
screwdriver.
.550 length  from top to start of taper.   30 degree taper to .293
diameter .410 long.
So how to translate all of this?  The .410 long .293 diameter plug part
extends into the head to fill the blind hole that whistles.  This is the
additional material that would not be there if you used a 1/2"-20
threaded 3/4" long set screw.

Kind of pricey though-

Rob Marks
NW Binders