did a compression test on my buddies ls/vtec motor and got extremely low numbers. pulley to distributor side read 120-110-90-120 and he's using the pr3 pistons(basically the pr3-3 head on the b18b block). could it be bent valves or burnt cylinder rings or a slipped timming belt. I'm also wondering if a leak down test would detect the problem?? please help us!!

 

Leakdown the motor, it will tell you everything you need to know... If you got air coming out the breather on the valvecover most likely the rings are shot, air coming out the intake indicates bent IN valves (same for the EX), take off the radiator cap... Bubbles coming from the coolant pretty much tell ya your headgasket is shot... If he's using OE cams I highly doubt that he tapped unless his T-belt was installed wrong, you would know that tho... Good Luck and let us know how it goes