It says in the instructions that came with the truck for the Pro28. If I recall it was something like 2 1/2 or 3....just guessing but turning it out 4 should be rich enough that you can lean it down until it runs right.

For those of you that are having issue with the remote glow plug wire; if you want to keep this system (I like it myself) you can buy a locking glow plug adapter, several companies sell them. I bought one made by dynamite, it screw locks on the glow plug like some ignitors do and it pretty much solves the problem of the wire popping off.

It won't work with especially tall plugs like the ODO99 and ODO100 however.