I just went to fit my first 13b sleeve into my 20b housing and found it is getting fouled up on a little stub of pipe inside the opening in the housing. Looks to be part of the casting of the housing and the 13b one doesn't have it. Do I just grind it off or do I need to be careful matching up the shape or anything with the outside of the sleeve? Maybe it is a pressed in part I can push out but I cannot see a join under the soot.
let me know please.

 

IIRC it can be tapped out with a screwdriver or punch and isn't all the way through the housing, it merely presses in about 5mm or so.

 

After scraping a way a load of soot you are indeed correct. Essentially they are a hollow little dowel. Now when it comes to putting back the sleeves I thought about getting new roll pins. Other than the end is drilled and tapped on mine they are fine so I could reuse them if they ate never seeing any load? I measured the roll pins and they come up as 5mm diameter and 12.5mm long. Of the shelf of course I can only get 12mm or 13mm! So do I go with new in one size or the other and grind down a touch if using 13mm long. Or just reuse what came out?

 

Just buy new roll pins...you should be able to find them no problem. Try a fastner shop or online. Last thing you want is a loose exhaust sleeve.

 

So get longer ones and carefully grind the length to suit?
will order some up.. I found them but only 12mm or 13mm engine ones measure 12.5mm long

 

try the 13mm pins, if they're too long then grind the ends off after installing them.

longer is better in this case, too short and the pins may work loose and allow the sleeve to rattle, or worse bend and block exhaust flow and possibly blow a rotor. yes, i have seen it happen.

 

Buy the 13mm ones, they will be shorter than 13mm. It's a manufacturing thing, they will always be slightly shorter so the will work without interference in an application that is actually 13mm. Dowel pins are the same was, as are bolts.