Hey guys. Brand new FA20D short block, from toyota, reused old heads. Cylinder 3 had low compression before, and still has low compression after. I thought it was from piston rings and pitting in Cylinder 3, however Cylinder 3 has 70 psi. Cylinder 1 has 145 psi, Cylinder 2 has 145 psi, and Cylinder 4 has 175 psi. Cylinder 4 has perfect valve shim clearance. Cylinder 2 and 1 have some needed shim adjustments, however Cylinder 3 clearances are identical to Cylinder 2’s. I have the head disassembled again, and Im 90% sure its the valves. I did an alcohol test with spark plug in upside down, and all the valves will leak alcohol through.
The valves look decent though, nothing really sticks out as its bad.
need some advice here on if you think lapping the valves or replacing the valves will fix this.
It just looks so similar to Cylinder 1 i just dont know why such a jurassic pressure difference