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Got the car started and right away noticed something isnt right. Heavy misfire but more like dead cylinders.
I tested for spark on all cylinders, inspected injector and ignition harness, and inspect injectors. There was a pinched wire on #1 ignition harness but I took care of that, did not solve the issue. Spark on all cylinders, clean injectors and fuel pressure.
I tested compression today and got 0psi on #2 and 6 , good compression everywhere else 140-150.
Tomorrow ill be pulling the valve cover to check for broken spring. The engine runs so I imagine it's not a dropped valve. Just gotta check for broken spring, bent valve, damaged rocker, bent pushrod. This is my crash course and first experience with LSx.
Looks like the previous owner had a tach installed, there was a wire running from the ECU tach line... dude probly money shifted. More tomorrow
Ok so I pulled the valve covers off and inspected all the springs. Everything looks seated properly with no visible damage to springs. I pulled the rocker arms off and inspected the pushrods, they are straight. I pulled the springs off the intake and exhaust on cylinder 2 and found the issue. I havent looked into cylinder 6...
It doesn't look like a bent valve, the stem runs straight and rotates in the guide very smoothly. The intake valve its perfect. I let the valve rest on the piston and rotated. It feels like a flat spot though on the exhaust valve. Rotates smooth resting on the piston until you get to a section that feels like a flat spot.
Without a visual, my money is on a burned exhaust valve. Maybe due to valve guide wear, but the valve stems looked clean and spun very smooth.
Previous owner had a tune/flashed ecu I'll bet it was tuned lean.
More back here when I pull off the heads on Friday.
Got the head off today and here's the damage. Can someone help tell me what happened?
Photos are cylinder 2 only, cylinder 6 has a valve seat issue with no damage to piston or head. I suspect the exhaust valve burned up for #2 and 6, but 2 got it bad.
I'm looking at two options:
Grind down the piston smooth, hone out they cylinder wall, pull the valves, get the seats reground, clean the valves and replace as needed. I'm expecting to replace the 2 exhaust valves. 500 total
or
Pull the engine, do a full stock rebuild replacing the piston with a used piston, all new bearings, seals, and rings. TSP ported heads. 2k total
I need advice on the best use of my time. If I can run the the engine for more than a year I'll be happy.
Doesn't look like the valves caused that. If that pic is the valves in question. It looks like something got into your intake and went through the motor probably bending the valves just enough to loose compression on those cylinders. Motor doesn't look lean.
As bad as that is carboned up it could be carbon at the base of the valve not letting the valve go into the guide all the way causing it to not fully seat.
As bad as that is carboned up it could be carbon at the base of the valve not letting the valve go into the guide all the way causing it to not fully seat.
I'm pretty confident that's what happened. There is similar damage on cylinder #7 piston, but the head was making compression.
11-19-2018, 11:45 PM
Compression test, 0psi, #2 and 6 
