Hey guys. Been a very long time since I've posted on this board but I finally got my car painted and reassembled earlier this year with my turbo chevy 250 setup. It runs great but it has been so long since I've heard it run that I forget if certain noises were always there or if this is something new.
The engine has .040" over forged pistons (piston slap?), roller rockers (valve train noise?), flat tappet turbo cam, Holley super sniper EFI (injector noise?), a SPA turbo manifold (exhaust leak?).
There seems to be a sound coming from the rear of the engine in maybe cylinder 5/6 that seems to be more pronounced on the passenger side. It's between a tick and a knock and seems to not be present at RPM/cruise/power. You can really only hear it at idle and it seems to fade in an out. The engine runs great and has plenty of oil pressure. I've reset the preload on the hydraulic lifters like 5 times but it never seemed to help so not sure if it's valve train related.
I was fairly confident it would be piston slap but I seem to only be able to hear it when the engine is hot whereas piston slap would be most pronounced when cold and slowly get better.
I've had a boroscope in the cylinders and there is no visible damage to the walls or piston heads. Plugs look great.
Timing is 15* at idle.
Curious if y'all have any thoughts or maybe 250s just sound like this and I'm misremembering.
69 Buick Special Deluxe. Intercooled Turbo Chevy 250 @ 15psi on a stock long block. It's kinda fast.
