I'm having a significant amount of smoke exhausting on deceleration. The car
does not burn oil and doesn't smoke on acceleration but when I let off the gas or between gears (particularly 3-4 it seems) I blow a pretty big cloud of
smoke.

This is a new problem. I don't have blowby.

I first noticed it last week on the dyno when Jeff (Creech) was tuning it.
After the dyno operator got to red line and let off, the shop would fill with
smoke. Jeff thought it might be bad valve seals. I've repeated the symptoms on the road.

The heads are Ported LT1's with Manley Race Flow Valves (2.0 Intake, 1.56
Exhaust), Comp Cams Dual Valve Springs, Comp Cams “R” Series Hydraulic Lifters, Crane Gold Race 1.6 Self Aligning Roller Rockers. I don't have the build sheet here but I'm certain the head builder used new valve seals and guides but I don't know what brand. They have about 20k miles on them. The motor is a forged 355 running 9.49 c/r and a 6psi Vortech.

Any confirmation on the valve seals being the problem or other ideas?

 

Definately sounds like valve seals and or guides to me. Lots of people resuse the old ones when doing springs or even mild port jobs. $20 IMO is damn cheap insurance. It is also easy to nick the seals when installing them as well.

I dont see you mention anything about your PVC / breather system. Worth a thought to make sure it is working.

Is the smoke a white / blue smoke or a black heavy smoke. Black heavy may mean running real rich under certain conditions. Does the car smoke when you let off at part throttle? Or just from WOT?

just thinking out loud a bit.

 

I'm 99.9% sure everything was replaced with new parts when the heads were done and that was 20k miles ago, I would certainly rather it be the seals than the guides though. I'd like to do the repair with the heads in the car

I plan to check my build sheet on Monday and see if new seals and guides are listed, if not, I will call the shop where they were done and see if he keeps a file and can tell me for sure.

Good thought; I did check all that.

[QUOTE=944v8inDFW]Is the smoke a white / blue smoke or a black heavy smoke. Black heavy may mean running real rich under certain conditions. Does the car smoke when you let off at part throttle? Or just from WOT?

Hard to say exactly as I see it in my rear view mirror but It's not very dark and it's not white white like head gasket white (been there, done that). I only see it under WOT conditions but it could be that under normal driving it just isn't as much or as apparent <shrug> As mentioned, it was just tuned last week by Jeff Creech (CAM) so I'm confident the a/f is right on.

That's exactly what I'm hoping for .... thanks!