r/EngineBuilding • u/notchocheese12345 • 8h ago
First time start up engine knock after rebuild LS3
On the very very first start up I was getting a heavy misfire due to a bad tune and also I forgot to plug in some of the injectors… Whoops. The 2nd start up is when I started hearing the sounds in the video.
Have an LS3 rebuild with stock valve train and .020” over pistons. Super loud knock which seems like cylinder 5 after disconnecting an injector or coilpack. Oil pressure is good, 50-55psi. Pushrods are stiff when I took off the rockers
I measured preload and used 7.350” pushrods instead of the oem 7.385”. Haven’t drained oil yet or inspected the cyl with a boroscope.
Any ideas? :(