Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

I just hunt around till I see a cartridge the proper length
and at least 200 watts.  It is important to add some, say,
1/8" thick metal strips alongside the cartridge to help the
heat get out of the cartridge.  A couple each side.  But,
I've never had a 90 boiler off the mount so I can't say
exactly what size you would need and how to do it. 

Good Luck,
Wayne