I first think engine run on from a carbon build up in the cylinders.
Did it have run on with the old carb? You can get top end spray that
you shoot the whole can in the intake while keeping the throttle
manually up so it doesn't stall. This can do wonders for that or a cup
of water can be sucked in to a vacuum line on the manifold seeing as you
can't slowly pour it in like with an updraft carb.

The carb should have a 'button' on the bottom that raises the internal
piston. When you push up on this, the rpm will raise if it's too lean,
bog if it's too rich or raise a little then mellow back if the mix is
just right.

The piston pot has to have oil in the center under the screw cap. Up to
the ridge I think it is. We used to use sewing machine oil, but that
spits out fast, I think 10W30 was called for.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Aug./05 http://www.imagestation.com/album/in...?id=2120343242
(More Off Road album links at bottom of the view page)

wrote:
>
> engine idling - i'm experimenting with air/fuel mixture,throttle idle
> screw etc. backfires when i shut off engine. What does this backfiring
> indicate? Thanks.