My truck!
I built that truck, and that motor in about 1997! A few things come to mind, the first being quality of fuel. That engine will not run properly on regular gas it NEEDS premium! If you are getting a lot of detonation, your plugs will look like that-and the tops of the pistons,combustion chamber etc. I sold that truck to a friend of mine in 1998, he sold it to another friend of mine in 2001, and I bought the truck back in 2005. When I got the truck back, it still had the same plugs,cap,rotor,wires etc, that I put on it in 97. By the way, I would ONLY run AC-Delco plugs in that engine! Anyway, when I pulled the plugs out in 2005, they looked brand new, engine was performing perfectly. I replaced all of the tune-up parts anyway, just because of age. As far as the breather goes, if it was super filthy, or plugged it could contribute to this condition. BUT, there is no-problem running a breather only! I have used this set-up on every BBC & SBC I have ever owned, including my boats and have never had one use oil, or have any negative effects because of this. After reading this thread, I also called one of the premier engine builders in the state of Washington to ask him what he thought. The first two things that came out of his mouth were "what kind of plugs, and is he running the same oil you ran?" As far as I know that truck had ONLY Lubrication Engineers straight 30, and AC Delco plugs. He also mentioned fuel quality, but stressed to me that before he tore anything down, that he would make sure to go back to the same combination of tune-up parts & lubricants that the engine ran correctly on. Another thing to mention here is the carb-if something went wrong in the carb, and it was running very fat it could wash down the cylinders, taking oil with it, and eventually leaving through the exhaust, but not in the form of smoke. I should mention that I have been a GM parts manager for 20 years, and this situation is also similar to the GM 8.1 litre engines. The 8.1 is a great engine, and was tested first in the marine market and proved to be an awesome engine. But, as soon as GM put it into trucks there arose an oil consumption issue right away. The problem was that in a marine environment, these engines were almost always under load. In a passenger truck @ 70 MPH these things were barely running-some still making 15-17 inches of vaccum @ highway speeds. The internal PCV system was not valved correctly for this type of use, and these engines were using 2-5 quarts of oil between oil changes (the ones that were used for highway travel UNLOADED).Once you put a load behind them, no oil use problem. PCV valve closed up and the engines were happy. Not sure if this could factor into whats going on with you, but I am pretty sure that up until you got the truck I do not think that it had a lot of highway travel. Every component in the cylinder heads was brand new high quality parts when I put it together. Heads are mildly ported, gasket matched,hardened seats,new guides, positive style seals,swirl polished undercut one piece SS valves, hardened push rods,GM roller rockers, all new camshaft matched springs, locks, and retainers. I would be surprised if there were a problem with the heads! The block is 40 over, has premium hypereutectic pistons, premuim molly faced (not chrome molly) cast ductile iron rings,etc. I did not go crazy, but I made sure that I used quality components in the entire engine. Don't know if any of this helps, but I hope so. Give me a shout if you have any questions-during the day @800-450-3600 Jerry. By the way, looking for another decent 84-5-6 K30!
. Thanks for giving me your number I lost it and I've been trying to track you down. 
