Corolla 2001; changed new head and valves, it have good compression 175 psi; but make lot knoking noise on the top, could be time chain the problem?

GREAT QUESTION.! OK now I see you have many posts and topic?
you need to have 1 post 1 top, (oil burner) do that use comment to the one post so it all stays as one.

YES ENGINES ARE AN AIR PUMP, HUGE.
EACH CYLINDER IS,
why not lead off with a real problem and all evidence first.
yes compression test can show 200PSI easy with 10:1 CR
both tests only prove the top 2 rings are good and cyl walls not scored hugely.( lead down at TDC)
no engine or maker told at all.

those other questions, about cracks
well gee , depends where the cracks are. and how bad they are.
freeze damaged water jackets? (you do know the machine chip pressure tests the block and head to find cracks not seen
and the cracks in heads can go anywhere wants. port, combustion chambers or water jacket to top if head OIL side. lifter side.

most times the leak-down test finds bad rings and is done at TDC.
so only finds cracks a TDC, unless you do tricky tests just after valves closed.

read the 100 point tests of of engine rebuild. it's huge. CHECK IT OUT FIRST.
oil consumption a question here?
oil control rings bad, or not seated or wallS with scoring
valve seals bad, are first to fail most time.
or valve stems guides so loose it beats the seals to *****.?
clogged PCV , and it burns more oil and leaks out seals.

the compression test is done , at 300RPM starter running.
warm/hot engine, not cold, all sparks out, W.O.T AND FULL BATTERY CHARGE ! factory manuals shows PSI to expect.
and is altitude dependent, (need chart ask)
AT THIS TIME THOSE PISTONS MOVE REAL FAST
AND WiLL IGNORE SOME SCORING AND CRACKS.
Due TO SWEPT SPEED ALONE.
and the test repeated with 1/2 teaspoon of oil, down spark hole if PSI jumps high rings are not seating.(for all the reasons)
SEE WHY LEAKDOWN FINDS MORE LEAKS ,IT'S SLOW

Wish I new what was the problem , at the beginning,
not told. what put you here, with no car stated, engine or size.

90psi compression is low in some cases engine may run but will be very weak and stall after a short time. a good petrol car compression should be between 120 to 150psi.
Does the engine oil light turn off after started, make sure u have oil pump up to the head, check the oil pick up inside the sum. The engine valves should not and never bend from no reason.

from finding on the list 93 psi is recommended but taking into account the age and milage of the engine it would coming as good. means the parts are wearing at the same time i.e valves and piston rings. if you wanted to make it higher psi you could clean and regrind the valves and change the piston rings but it would be a waste of time as it is only 3 psi out. maybe give engine an oil change this can bump up the psi in an engine. use a slightly higher oil rating. as engine is old now and it will keep running for a longer time.

You may be in luck! your engine may have a squash plate on the heads. This will keep the valves bending. Put the new chain on it-MAKE SURE THE TIMING MARKS LINE UP! Then do a compression test to be sure. I've had a timing belt break at 10 miles over the "suggested " change mileage, and that plate save the day.

contact the parts store for specs they should have it on the computer system under overhaul specs..ask for a printout of rebuild proceedures..

well, that is a tough one. not being there, no indication of valves hitting pistons is not a very good check. if the chain jumped, it is very likely the chain guides and chain wore out from mileage or lack of maintenance. how many miles are on the vehicle?

The lowest cylinder should be about 165 PSI, you have big problems here or faulty test equipment.

compression reading should be between 175-225lbs... 25 is extremely low so timing could be off

Your timing chain has jumped a tooth or three. Replace the timing chain.

Yea, because what probaly happened is that, you dropped a cylinder or two...which means you probaly have bent valves..that's why your compression is way out of wack...I believe that engine is an interference engine..so when the timing became off, the piston hit the valves..and bent them...You can take the heads off and have a machine shop, or you, can put new valves in it...Good Luck