I have a 79 460 Camper Special that has me a little stumped. I posted about this before but I wanted to try one more time to see if I could garner any new data. The truck does not smoke when cranked cold, in fact there is only one situation where it does puff. After running at 55-65mph for a few miles if you get off the gas, to turn off the highway for example, and get back on the gas after slowing down, a sizeable cloud of blue smoke exits the exhaust when you get back on the gas. If you come to a complete stop, no smoke. The compression is 140-150 on all cylinders. The PCV valve is new. I removed the valve covers and all the breathing holes are open, all drain backs appear to be open. The valve train and valve cover areas are exceptionally clean with no sludge. The modulator valve on the tranny is not sucking any fluid. The truck only has 78000 miles and obviously is not driven that much. One suggestion from another poster earlier was valve guide seals. This almost makes sense, but then why doesn't it smoke when cold cranked? I see no evidence of oil in the coolant or coolant in the oil. Any ideas out there?

 

I'm kind of fishing here but who knows! It soumds to me as when you are letting off the throttle at the higher RPM's you are pulling oil into the combustion chamber somehow the question is where. To me only two places come to mind where it could be taking place. 1)Is through the PCV valve or through the oil cap into the air filter housing. What does your air filter look like? Is there alot of oil on and around it? For some reason you are getting alot of pressure in the crank case which usually means rings but you have good compression so I would omitt that. 2)Maybe you have a leak in your intake gasket and it is just pulling a noticeable amount of oil in at high vaccum. Just a few ideas foryou no real sollutions. Good Luck.