Some of my experiences
The idea of adding mesh to burners is to slow down the velocity of the gas / air mixture in the burner, something that gas boiler manufacture's [ for heating / hot water in the home etc ] did with old style boilers, nowadays the burner is more akin to a jet burner being able to have a variable burn producing heat as required.
I have a Accucraft Superior, I tried the SS mesh inside the burner and found it almost inpossible to light, perhaps it was to much for the old burner. After some thought I came up with the idea of a baffle, this basically is a piece of copper which covers the end of the boiler in the smokebox, it's about 1 1/2 x 1 1/2 with two bent side walls 1/4 running top to bottom to form a wide U shape the bottom was curved to match the inside of the smoke box held in placeby two legs at the bottom that were attached to the baffle to run for and aft in the smoke box floor. This worked well, I then removed a chuffer that had been fitted as this seemed to hold back the engine this the leaves a fitting with an M5 internal thread
[ I think ] to direct the exhaust up the chimney I found a piece of brass tube that was a tight fit around the fitting and slid this on to it so that it finished about halfway the smoke box, I now have an engine that now can work a decent load and has a natural chuff.
Shaun
