I have a 71 mustang w/ a 302 and just noticed it started burning oil. It goes through a quart of oil every other gas tank fill up. Its not dripping as it leaves no spots anywhere it sits. The engine has less than 5k miles on the engine rebuild, but i do not think that the previous owner rebuilt the heads. When i start it up, it smokes out of the one side( i dont have a valve cover breather/pcv on that side like i do on the opposite side). My guess is the valve seals are leaking, then it smokes on startup. Also its oil pressure is at 60 when i start it up, and after 30 mins of driving( hot) it gets to between 30-40 when idling, depending on how hot it is. What is the lowest the oil pressure should go to? Im using 10w30. Im guessing the oil thins out from heat, then the pressure goes down. I also put in an electric fan this past week and it runs a lot better, eliminated by neverending belt squealing. The fan only turns on after the car is fully warmed up via a 190 degree thermostat. the fan usually doesnt kick on till 15 mins into my drive. any idea's on why its smoking, loss of oil pressure, and loss of oil? -Jon

 

A quart every 500 miles or so sounds excessive to me.You are probably right in yourassumption that your heads need attention since the lower end was overhauled recently.

 

10 psi is the minium for for each 1000rpm an street engine turns as a rule of thumb

 

That's true Stephen, but this guy is burning a quart every 500 miles. He has a rebuilt bottom end, but not a top end. The problem seems to be the valve guides that need an overhaul.

 

Time for some nice aluminum heads methinks Or at the very least a valve job on the ones you got

 

Definately sounds like the valve seals.. Your oil pressure is fine at 30-40 ,, I tore mine down because it was dropping to 2-5 at idle and my bearings were the problem..