HighspeedLean

iTrader: (2)

LS3 head castings on my 416. Right side rear cylinders #6 and #8 are oiling the plugs pretty bad. I pulled the intake and looked in runner and saw oil puddled on backside of intake valves. I pulled the head and found the piston top clean of carbon along with the head chamber. What carbon was there I can wipe off with my finger. I read where the bolts that hold down the rockers can seep oil under vacuum so I re-installed the head and used a liberal amount of sealant on the bolt threads. I let the sealant a day to setup good and started the motor in the garage. Same issue.... At first I thought rings were being bypassed or one was damaged, but no visible marks or scars in the cylinder while head was off...compression test shows 185-190lbs. on all the holes and leak down was 6-10%(cold) on all holes. Heads were CNC ported so I thought the spring seats were breaking through under load, but the area where the spring seat are located weren't touched by the cutter.

Anyone have this issue before?

blk00ss

iTrader: (66)

Yup. I never figured it out either lol. Just kept oil added to it. Stock bottom end or is it a stroker? And what rings?

HighspeedLean

iTrader: (2)

4.0" stroker, K1 forged, Wiesco pistons +5cc dome, rings that came with em'.

dogsballs

Stem seals? Or worn/cracked guides?

HighspeedLean

iTrader: (2)

Brand new casting 40 passes ago....but anything can/could happen.

Pulling the head off tonight to have pressure checked to see if a hairline crank has developed someplace. The motor doesn't run badly, doesn't smoke at all, but it's still there.......interesting that it is only 2 holes next to each other.

Vito.a

I'm not sure I'd pull the head again.
Does your PVC system pull vacuum from the valley cover?
Do you have an oil catch can installed in the PVC system?
What kind of valve stem seals do you have on the intakes?

HighspeedLean

iTrader: (2)

Track only car...vacuum pump yes...what's a pcv? Plumbed to the valley cover with baffles. I can race all weekend and only get a tablespoon of oil in the catch can.
Valve stem seals are what comes with BTR spring kit.

Vito.a

Star Machine vacuum pump plumbed from the valve covers to a catch can?

Check the intake valve stem seals on 6 & 8 carefully before you pull the head.
Were the rocker arm bolt holes visibly drilled through into the intake port.
Have you done a leak down check on 6 & 8 to see if anything is leaking around the rings?