what is the small spring near inlet valve?I have never seen before.
What engine are you working on?
It is mitsubishi lancer box 1985 car and orion "4G12B" engine. The spring is directly faced to this like that picture.And thanks a lot for you reply
United States passenger car versions had a small secondary intake valve, called by Mitsubishi the "Jet Valve", to induce swirl in the intake charge, enabling the use of leaner fuel/air mixtures for lower emissions. Rather than redesign the head as three valves per cylinder, the Jet Valve was designed as a cartridge containing the valve spring and seat which simply screwed into a threaded hole in the head, similarly to a spark plug but inside the cam cover, thereby reducing modifications to the head design to simply providing the threaded hole. The rocker arms for the intake valve were widened on the valve end to accommodate the extra valve, which was equipped with a very soft valve spring so as not to increase wear on the camshaft intake lobe.
A little more info is here at the link.....https://en.wikipedia.org/wiki/Mitsubishi_MCA
Thank a lot for your answer.It is very usefull.
I thought I knew nearly everything about modern engines, but I have never heard of this. I learned something today, thanks for posting.
You are welcome.