Having an issue with my big block. The casting # is 361959....I don't know what the internals are like (maybe stock probably not), but I am having an issue with gray smoke on deceleration. I have a new Holley 750, Edelbrock performer 2 manifold, summit racing ignition, 280/520 cam, and iron heads (casting #3904390 closed chamber). The smoke is ONLY on deceleration. On another note, I am using A LOT of oil....like a quart every 100 miles or so (yikes!). no leaks at all under the car. I am hoping it isn't rings, and the fact that there is no smoke any other time makes me feel a bit better about that. The PCV system seems ok, although I have not looked at the baffle yet (I was told after researching the valve covers the baffle looked OK, but I am traveling so I have not put eyes on it). The PCV valve itself is spotless. I am pretty focused on the heads....I originally wanted to go with aluminum, but I am not sure they make closed chamber aluminum heads, and without knowing what the pistons look like, I am at a stopping point. I am considering having the heads rebuilt, but am I limiting myself from a power standpoint? It would seem I have some options open to diagnose (torquing the manifold, checking the baffle, possibly replacing the PCV with something I know is for a motor with lower vacuum), etc. I am beyond my grade level as far as mechanics go, so I barely treading water here. I live in the DFW area and am amazed that I can't find a good mechanic to help solve this issue. Thoughts?

 

Time for a compression check, could be bad rings but could be as simple as valve guides.

 

Blue smoke upon deceleration: worn valve guides.
Blue smoke upon acceleration: worn piston rings.
Blue smoke only upon start up: worn valve stem seals.
Also make sure your PCV valve is functioning properly, even if it does look spotless

 

thank you for the replies! I pulled the PCV valve yesterday while it was running and it was puffing vapor out of the hole.....not good. Dropped it off at the shop and they are going to go over it. Check the guides, take a look at the pistons, compression test, etc. At this point I am not opposed to a complete rebuild...its an unplanned investment in an already expensive car, but at least I will know exactly what I have, and get some more performance out of it as well.