I'd like to solicit some opinions of this list on
the most likely cause of burning some oil.

First, some background:
The motor is a 85K mile Vette L98 that I picked
up to replace a hot-rodded SR 355 that expired.
I replaced the valve-stem seals while the motor
was out of the car. I have some concern that
some of those O-rings on the exhaust valves
might have slipped out of the groove while I
was compressing the springs to get the keepers
back in place. Not sure if that matters or if
they will naturally be pushed back into the
proper place in the groove.

Also, the 2 kits I got only had intake seals,
I was told by both GM and the parts dude at
the parts store that the exhaust seals were
not replaceable. So the kits came with 8
of the rubber umbrella seals for the intakes
and the rubber o-rings for the valve-stems
for both intake an exhaust. Is this right?

I also checked all 8 cylinders and all have
proper compression (155-165psi).

The symptoms:
Smoke out the tailpipe - good amount on start-up
intermittent but generally steady smoke at idle.
Doesn't seem to smoke at all under cruise
conditions, or at WOT or decell.
Intake is clean, so it's not sucking oil back
into the TB. Also no crankcase smoke / blowby.

Any clue as the likely culprit?

Scott
'91 Corvette - L98, SR, DFI, 6-spd
'68 Camaro - 383, AT

 

I have the same heads and my intake & exhaust both had the Teflon lower oil seals as well as the O-rings in the upper valve stem groove.

With smoke at idle it sounds like rings unless the engine is running very rich.

 

Wouldn't bad rings show some blow-by and also smoke under decell conditions?