Skip to main content

Grey Smoke During Deceleration

On Sunday I took my 74 Pantera out for the day with OC Panteras and put about 100 miles on it with a lot of starts, stops, and a few spirited runs. While it worked well overall, I learned that the car outputs some grey smoke primarily during deceleration. I could not see smoke in the mirrors except one time when I accidentally lugged the car.

The engine has .030 over pistons, a hydraulic roller cam, adjustable roller rockers, big pushrods, and stainless valves.  The cylinder heads are open chamber and probably original to the car.  I purchased the car with the cylinders heads off due to a blown head gasket.  There is no lip at the top of cylinder walls indicating that it does not have high miles since the engine work was done.  I took the heads to a shop and they did a complete valve job including new seals prior to reinstalling them.

I am trying to figure out the source of oil that is being burned. Typical sources are worn piston rings, worn valve guides and/or seals, and malfunctioning PCV valve. The inside of the intake manifold is clean which tends to rule out PCV.

Someone suggested a compression test and the results are below.  The test was done with the engine warm, all spark plugs removed, throttle wide open, and ignition off.

I appreciate any suggestions from you guys.



Images (1)
  • 08F8596B-D406-4A1C-BE13-A5D5E45BA485
Last edited by stevebuchanan
Original Post