O pai ainj na karaia karo maray bandaya day naal
Do you know what is the purpose of valve clearance? They are just for the purpose to allow metal to expand when hot, if their is no or less clearance the metal will bend. So the tappet clearance only makes a difference of 19-20 not that much so that you have change the cars intake setup etc.
You cannot do miracles with just tappet adjustments, people who modify their cars also change their engines cam profile so that valves can go further down in the cylinders to let more fuel inside the chamber. If you observe the tappet clearances are 0.008-0.010 inch while the cam profile allows the valve to move around an inch or less so it is 0.8-1 % or lets say 5% of total valves movement. Now tell me how much difference those 5% can make.
Guys dont get me wrong here I am not saying that tappet clearance wont do any harm to performance yes it would do but it is not possible that due to tappet adjustment you have to block the air intake for proper functioning of the car.
Now I tell you why mechanics love to block the air intake it is only because they learnt so from their ustaads thats it. I had a nissan sunny 1.0 dx CNGed people told me to block its intake I did that pick went bad but the mileage did not improve because I had to push the car harder removed the blockage and pick improved with no change in mileage. In the meanwhile I had to retune the CNG 2-3 times.
On efi cars properly calibrate the advancer emulator and than re adjust the CNG and you are good to go, CNG blockage is not a thing that car can not work without it