70rcode
Well-Known Member
Anyone know where the often quoted "> 20 Hg" = Good Pass valve Job Internal vacuum test requirements or recommendation originated from ? Seems like most of the Professional head machines (Serdi, etc) Vacuum test gauge reads about 20-22 Hg inches into a perfect seal (like a finger tip or airtight plug).....Is that relatively Low vac gauge test standard reading intensionally designed that way for some reason ?? ...
