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

I just now checked out the S/V on my Wilesco D22 and it is pretty stiff, the shaft that goes through the spring is flared out on the end, you could grind that flare off & then try to re:flare that end, making the shaft shorter , thus putting more "crush on the spring & raising the threshold of PSI it would take to release the pressure of the boiler. that's all assuming you don't bugger the s/v while attempting all this. it would be better to make a new "adjustable" S/V.