Greetings all from Canada.
I had the heads on my 312 done June 6 because of a bad misfire on #5. When the heads were done the machine shop stated that the valve were all in good shape. He put in hardened valve seats on the exhaust side, cleaned & rebuilt the valve train. The car ran great for about 4-5 weeks, very smooth, no carbon tracks out of the tail pipes and the exhaust smell was low. Last week I noticed black oil dripping out of the downdraft tube. I smelled a strong trace of fuel in the oil. I suspect it is wash down. I pulled the plugs, and found the 4 rear spark plugs vary a bit but are all clean dry and slight degrees of a tan colour. The front 4 plugs generally are a bit darker than the back, but #5 and #2 are very black, fouled & misfiring. There is a stronger smell of exhaust & some carbon tracking out of the tail pipes. There is no oil residue on any of the plugs. The car does not smoke. When the plugs are clean it runs very smooth without a hitch and has good power. It pulls about 18.5 inches of vacuum with a steady needle on the gauge. The valve lash was just recently checked and are spot on. I have tried swapping clean plugs from the back cylinders to #5 & #2 but they fouled within 5 minutes. I have put about 1000 miles on the car since the heads were done. All plugs, rotor cap & wires are all new. I am running Pertronix ignitor 1 and the MSD Blaster coil. One thing I noticed when the heads were off was how little carbon build up there was on the piston tops especially on #5. I hope I did not do any damage with the wash down.
Does this sound like piston rings are gone? Any ball park price on an engine rebuild?
Thanks all